Tuning Tricks, Antenna Trimmers and Observations

       This weekend ( November 14 and 15, 2015) has indeed been an adventuresome weekend on the radio.  Three new  band-countries jumped into the log.  I call it a "band-country" when its a new country on a given band.  In this case it was Willis Island as the current DX-pedition got underway and I managed to snag them on 12 and 10 meters for the first time, having logged them on 15 meters from an earlier trip to the small island.  This is an example of how the only way to put a country into the log is via the amateur bands, because there is just nothing else there to generate a receivable RF signal! That takes my 12 meter total to 173 and my 10 meter total to 216.
       The other was Ascension Island heard for the first time on 80 meters, taking my 80 meter country total up to 118. I realize my total on that band is not that impressive compared to the " big guys" but given the size of my antennas and my relatively noisy location,  I am happy with any new one I can get! Of course this did not add to the overall countries total because Ascension has been there for a long time thanks to much more powerful transmitters pushing out the BBC's signal!
       Overall it was a pretty good weekend to be listening.  It was rainy most of Saturday and outdoor chores had to wait. The bands were fairly good. Friday night 40 meters was very good.  While it was not a new country, it was a thrill to hear Kenya , Western Sahara and the Canary Islands on the ham bands between what was actually 0200 and 0300 Saturday the 14th.
        Earlier time in the evening was unfortunately spent in front of the television watching coverage of the tragedy in Paris.  It also appeared that the BBC was quite strong in several spots, leading me to wonder if they did not lay on some additional transmitters and beam headings that favored the US for their coverage.  Perhaps some of you who keep track of them more closely might add comments. I could post them later if you should notice such.  International events often generate transmissions that are outside the norm.
       Saturday morning Texas time listening began about 1300 GMT. ( OK, so I slept in a bit!!) The initial WWV sweep showed it would be a good day. Beginning at 1348 GMT, the  2.5 MHz  WWV was S-9 + 20 DB with WWVH from Hawaii just barely detectable in the background. The 5 MHz WWV was S-9+ 20DB with WWVH clearly audible behind.  On 10 MHz WWV and WWVH were about equal strength with the S-meter at 20-over. On 15  Mhz surprisingly WWV was S-8 to S-9 but bouncing around a lot with no signs of WWVH.  The best was yet to come!. Even this early with sun probably just rising at their transmitter site, WWV on 20 MHz was already up to S-5 and S-6 and was clearly audible on 25 MHz!
       I noticed when checking the amateur contest listings for the weekend that the OK/OM DX contest ( Czech Republic and Slovak Republic respectively)  was going to be on CW and the JIDX ( Japanese) DX contest was going to be on phone.  That would mean some possible DX targets two ways.  One, it would be fun to see how many Czech and Slovak stations could be logged on CW and how many Japanese stations could be logged on phone on difficult bands.  But also, these smaller contests are also ways to log other countries listening for stations calling those hosting the contests.  The trick is often to listen at times when prop is NOT good to the host country and to listen for other DX stations calling THEM.  The " trick" is to look for pileups or to look on one of the spotting websites like DX Summit and look for stations host country hams are posting that might have prop to you and go park on those frequencies.
       Of course for listeners within the host countries its an easier deal.  Find a station in your country that is working a good run and park on that frequency and let them bring the DX to you!
       Or, if there is a relatively rare station working the contest in your continental area that those working the contest in the host country would probably like for a points multiplier,  park on HIS frequency and let him attract the DX to you.  This works particularly well on the " hard " bands for hearing the host country.  For example, here in Texas listening on 160 or 80 meters if there is a Caribbean station working the contest parking on his frequency will increase your chances of hearing the host country's stations on a tough band.
       The same works for DX-peditions. For example, this weekend was VK9WA on Willis Island was working stations and telling them to call  " up" or above their working frequency.  By tuning off the expedition and into the " pileup zone" you will find lots of goodies to put into the log.  It may take careful tuning and highly concentrated listening to pick callsigns out of the pile, but it can often be worth it.  QSL's sought from these stations will be easy to get as well, because you can believe those operators will remember the time and place where they were trying to bag a good one!
       For those whose CW is just developing, listening like this is great practice.  It always help in building speed to listen in deep concentration in tough conditions.  Also,  anyone can copy for short bursts at a much higher speed than their average copying speed.  As in physical exercise,  "stretching" always leads to improvement!
       This also applies to listening in pileups on phone, just in a different way. It will help develop your " DX-er's ears" by helping to develop the mental technique of pulling what you want out of apparent chaos through concentration. 
       In both cases,  phone and cw,  it may take callsigns going by several times to allow you to pick them out.  You will find yourself getting one letter at a time, until the entire callsign is filled in.  I usually write them down on scratch paper and while digging in a pile, either add each new letter to those already written down, or drop down a line for each "listen",  finding sometimes it may be required that a letter be changed because it was not heard properly the first time.  For those familiar with mathematical terms,  I guess you could say this is a form of " mental integration"!
       I have found that the same "mental integration" technique works in trying to identify a station down in the noise.  Listening over and over and over will sometimes have the signal fade up and down or noise bursts be present or absent in different places to let the ID finally pulled out and another one in the log!
       Of course the old hands reading this will be saying " I  knew that all along" but maybe trying some of these things will help the " newbies" learn a little faster, develop mental acuity and perhaps avoid frustration that might lead to ( "gasp!") dropping the hobby!
       These techniques can also be used for DX-ing other things than just the ham bands. Broadcast stations ID's or clues to identity can slip by quickly.  For those who run audio recordings, often running them several times will allow some form of mental integration.  For those with SDR's, the same might be the case, perhaps with different passband or selectivity settings.  For those who take the hobby beyond just listening to programs this could lead to bagging a good one rather than letting it go by because copy is tough. ( not that just listening for programs  is not a good thing, there are some great cultural things to be experienced listening to SWBC not to mention the exotic feel of listening with the fading and knowing you are doing it yourself without intervening wires...I am sorry but listening on the internet is just NOT the same!!!)
       OK, so back to Saturday morning. A quick check of twenty meters showed European signals coming in already at 1400 GMT. They were not strong but were readable. Many had a marked echo on the signals, indicating either multiple arrival paths or multiple backscatter effects. 
       Sometimes when signals sound like that here in Texas it is when they are passing through the auroral zone and are generally from Northern Europe ( particularly Scandanavia) or parts of Russia.  In this case, however,  the echo was pronounced on many Southern European stations.  Regardless of the mechanism, such makes copy of CW signals difficult because the delayed or echoed sounds tend to fill in the gaps or spaces between the " dits" and " dahs". 
        On voice signals, it makes understanding the words very difficult. The effect can be quite interesting sometimes.  I have heard instances where prop has brought signals  from Asia to my radio by both long and short path at the same time. There have been times when the long path was actually stronger than the short path and the "echoed" syllables were actually stronger than the "original". I still remember the very first time I heard this effect and was amazed.   It was in 1959 or 1960 while using my first, home built shortwave receiver and heard the Voice of America relay station from the Philippines early in the morning on 31 meters for the first time.
      In any event,  there are a few things that might be tried to make either the phone or CW signals more readable. The first thing to remember is that the Automatic Volume Control ( AVC) or Automatic Gain Control (AGC) is doing its best to "level out" the signal.  On CW particularly this means bringing up the gain when signals drop in level  or are absent.  This means the AVC ( or AGC) is actually aggravating the situation by making the echo and original signals the same strength.
       The first thing to try depends on whether you have a selectable AGC speed.  If so, select the slowest speed.  If not, it will be necessary to find some way to reduce the AGC effect.  The only way to do this is to reduce the strength of the signal to the point that the AGC has no room to "recover gain". If you have an RF gain control, back it off. If you have switchable attenuators, switch them in. As long as the signal is audible, it matters not if the S-meter is swinging above S-9! If there is enough difference in strength between the original and echo signal you might find a point where it becomes more readable.
       The same can be said of phone or AM signals. The effect may not be as pronounced and in some cases will not help much, but it doesn't help to try.  In some cases where the signal is " just ALMOST readable" every little bit can help!  The technique works better on SSB phone signals than AM signals.
       One other thing you might try if you have more than one antenna is to select a different one. A different antenna might have enough of a different pattern that one or the other of multi-path signals might be reduced or enhanced.
       For hams working CW and trying to make a contact with a station marked by heavy echo,  if its on a path going through the auroral zone,  be aware that your signal is being affected in exactly the same way on the distant end. If signals are strong and the other station is not answering your calls even though you know he must be hearing you,  its possible that the echo is making it impossible for you to copy you regardless of strength.  The answer is to slow down. Not just with more space between letters with your keyer or bug sending letters at the same rate,  but actually slowing down the  letters to allow more space between "dits" and "dahs". 
       I keep a straight key in the circuit wired in parallel with the output of my electronic keyer to allow quick and easy switching to a slower speed.  Often this is the difference between being just heard and actually copied.  This technique can also  be used in other times than just multi-path or echo situations.  Sometimes it can work in pileups and other heavy QRM or QRN situations.  When its tough, whatever works !!
       During part of the weekend's listening,  I switched away from the R-75 I had been using and fired up my old Hallicrafters SX-111. I still think this is one of the prettiest of the old boat anchors.  When I was in junior high school, an older fellow who was in high school at the time and an active ham  lived across the street from one of my aunts.  I would visit him frequently and he was  a great help with learning the code and generally learning radio in general. He had an SX-111 and I remember thinking it was really something. It was so much more stable and selective than the little National SW-54 I was using for SWL at the time.  I guess when the opportunity to do some trading to get one years laer presented itself,  it just would not do that I would pass it up.
       By the way, it is unfortunate but I have lost track of that ham over the years.  His name was Lou and his call was K5HFR. That call is not active in any data base now and of course many people have changed callsigns or obtained vanity calls since then and I have not been able to trace him.  Of course it could  be he is no longer active.
       In any event, as I fired up the Hallicrafters it came to mind when I switched to forty meters and calibrated the dial that for some reason I was struck by the need to adjust the antenna trimmer.  It occurred to me that many who use these radios today as collectors or who did not use them in " the day" may not know the purpose of this control.
       On these radios,   tuning is accomplished by multi-gang variable capacitors.  One section or "gang" tunes the mixer input, one tunes the local oscillator that generates the signal to convert the incoming signal to the Intermediate Frequency and if there are third and fourth gangs they tune the RF amplifier (s).  They must all track together to maintain even gain across the band.
       The rub comes in when an external antenna is connected to the receiver  Even if link turns on the coils are used to couple the input signal into the first tuned circuit,  capacitance of the antenna system can "load " the circuit somewhat and cause some detuning,  meaning the first tuned circuit will be pulled down in resonant frequency somewhat and might not track properly.  The antenna trimmer control is used to counteract this effect.
       There are multiple ways  it may be done.  In some receivers, the antenna trimmer is simply in series with the incoming "hot" lead of the antenna, with the idea being series capacitance will minimize the  capacitive loading effect ( see any electronics book on what happens when capacitors are connected in series).
       In some receivers the antenna trimmer is a small capacitor connected in parallel with the input tuning variable. In alignment, the first stage is tuned with the capacitor partially or nearly fully meshed.  Then when the effect of additional capacitance from the antenna is added,  by turning the antenna trimmer to a more un-meshed position, the effect of the added antenna capacitance is effectively nullified.
       It is not necessary for the receiver operator to know which method is used or in fact how it all works.  All one must do is when one stops in any general part of the band is to rotate the antenna trimmer control for maximum  signal. Any time you move an appreciable amount in frequency,  just peak it up.
       This is not to be confused with the preselector tuning in some receivers.  That is a whole 'nother deal!
       Hope all of this has been of some help and not just the rantings of an old guy! To many of you, this might be old hat,  but to new guys or folks dealing with boat anchors for the first time, some of it might be useful.  For those DX-ing the ham bands, it might be of some real use. As I have said before, none of these techniques should be taken as " the only way" but ways that I have found that work for me and hopefully will be of some assistance to others.
       Happy hunting and good DX!

Was it Really a Poor DX Weekend?

       This past weekend ( November 7-8, 2015) was supposed to have been a poor DX weekend. And perhaps in some aspects, it was.  There was some solar activity and there was to have been a solar mass ejection that was to reach Earth and cause radio blackouts and such.
       There were complaints on Facebook of dead bands and poor signals from stations that are normally heard well. There were also not the usual high strength  DX signals obvious on the amateur bands.  However, as is often the case in fishing,  when the fish aren't biting in the usual holes,  they might just be found somewhere else. It also might be that the openings were there, just shorter and during limited times of the day. And the third possibility,  the DX signals were there,   just from different places than usual and at lower signal strengths.
       In the case of this past weekend,  it was a combination of all of the above.  I am not certain what the mechanism of the appeared malaise might have been.  It could have been a result of a hiccough on the sun, the CME or maybe just the overall low solar activity coupled with the change of seasons. In some cases it might have even been folks looking for broadcasters on frequencies they had abandoned with the seasonal frequency shifts and they were just in different holes.
       My own tuning actually started a little late in the weekend. It was Saturday morning a bit before 6 AM Texas time or about 1200 GMT that I woke without the usual alarm that during the week goes off about two hours earlier.
       After the morning ritual of feeding animals, walking dogs, making coffee, etc, I managed to get in front of the radios about 1220 GMT.  The sun was already starting to lighten the sky.   I used the R-75 and  80 meter quarter wave sloper ( which is actually a little long for the band, being about 80 feet long) top fed with the feedpoint up about 45 feet.
       I like to start with a sweep of the  WWV and CHU frequencies first to get some idea of what the bands are doing.  They are always there, with predictable schedules and signals and known antennas and give a good day to day picture of what generally is going on.
       It appeared things would be a little abnormal when there was no signal at all to be heard on 15 MHz. I didn't really expect to find anything but quickly checked the 20 and 25 MHz spots.  Absolutely nothing.
       The 2.5 MHz signal for WWV was a blistering S-9 + 20 DB!  WWVH was also audible very strong behind it.  The surprise came with a check of the 3.33 MHz spot for CHU and it was already gone.  The sun had come up at the transmit site and prop to the east was already gone.  Well!
       Let's check 5 MHz.  WWV was S-9+20 DB and WWVH from Hawaii was almost as strong! Then 10 MHz told the rest of the story.  In the mild static crashes present locally that morning, I at first thought there was nothing there. But then came the top-of-the-minute beep and I knew something was there,  but I had not heard the WWV voice.  Waiting another minute for the time station cycle told the tale. WWVH was coming it about S-5, but WWV was not to be heard.  Interesting!
       The 15, 20 and 25 MHz positions showed no sign of signals. A quick scan of the 10, 15 and 17 meter amateur bands showed nothing.  Not too much of a surprise there.  The only band that has been showing any signs of life even occasionally this time of the morning the past month or so has been 17 meters.
       So that's how  we started Saturday morning. I knew it was probably too late, but I checked the 120 meter band, hoping perhaps to hear the  Northern Australian stations, but they were gone.  No signs of the Koreans or the Papua New Guinea stations on the 90 meter band.  the closest thing to Asian DX I found was way up on 4940, one of the Chinese stations was coming in, actually rather well. Up the band a little bit radio Rebelde on 5025 was still S-9+20 DB but its band mate radio Havana on 5040 was missing.
       Up to 49 meters we go. On 5830, WTWW was blasting through, then 5875 BBC World Service from Thailand was about S-5, doing the usual Southeast Asia morning bounce on the S-meter. Another Chinese station on 5915 was not so strong, struggling to S-4 with the same bouncing level.
        I knew that stations up in the higher bands had probably changed their seasonal schedules and the usual spots I checked might not be updated yet on them, so I switched to the amateur bands. By now it was  1330 and I knew it was getting late for the Pacific on 40.  Even at that, usually the Japanese stations roll in well past sunrise.  However, it was not a major  contest weekend that would draw large number of them out and even the small contest of the weekend, the Ukraine Contest, would not likely turn a lot of them out on 40 meters at this time.  Forty would already be closed to DX for Ukraine with the sun well up there. And such was the case: only one lonely Japanese, JS1SUT was found on 7025. I should have gotten up earlier!
       The next fifteen minutes tuning around the band proved it all out.  The short skip was in. Northeast US stations were already weak with their sunrise complete.  The West Coast stations were ok and either in "local" QSO's or hopefully calling CQ DX.  Only the Midwest stations were stoutly over S-9 and involved in local chats.
       Thirty meters showed the same thing. Mostly US stations either calling CQ DX without much luck or involved in US to US QSO's. What was the deal?  The band was obviously open.  Some of the stations calling CQ DX actually were showing signs of backscatter and echo from return skip from very distant locations. Had everyone just believed the dire predictions of bad prop because of solar activity and CME's? Were the Asian stations all on the higher bands working the Ukraine contest?  Where was everybody?  WWVH was if anything even stronger on 10 MHz now.
       A quick tune down just a bit from WWVH showed that there were broadcast stations coming through.  At 9975 was KTWR from Guam at well over S-9 at 1358 GMT.  The band was not dead, just open to a little different place than usual. Still not knowing for sure if the usual places where broadcast schedules  were posted had been updated,  I decided to default to the ham bands.
       A little aside here: It seems I have become a little spoiled by the readily available freshly updated station lists and schedules.  I guess we all have gotten used to the almost  " instant gratification" of easier station identifications.  Its easy to forget how things were back when I started SWL-ing in the fifties and sixties where there were few updated lists.  Even the WRTH was months behind some schedule changes the day it came out!  And other lists such as White's Radio Log did not even have schedules,  just long lists of frequencies used by the various stations.  In those days it took long, sometimes tedious periods of listening to pull out an ID and then try to figure if what you heard in those fleeting seconds was accurate.  Of course the stations in those days used Interval Signals or pieces of music  around ID time that helped out.  Those DX-ers who had the money and luck to have reel to reel audio tape recorders had at least a leg up in being able to record the ID breaks and play them back over and over in hopes of picking out the ID.
       So anyway, it was up to the 20 meter ham band I went without a lot of confidence,  with all indications being that the Maximum Useable Frequency ( MUF ) was probably just over 10 MHz. Wrong!
       There were stations there!  The Ukraine contest was underway and tuning up from the bottom of the band I immediately ran into K3WW at 1410 GMT  on 14007 calling "CQ Test".  He was fairly strong, RST 579,  leading me to believe that this band, too, would be a fairly short skip affair.
       Wrong again! The next signal I ran into was at 14019.5 and was also calling " CQ Test" and working stations.  He was not as strong,  only about S-4, but readable.  LZ5W from Bulgaria was having a fair time of it ( a signal heard often here during contests!)  This was at 1413.
       The band at first glance did not appear to have a lot on it and for the uninitiated it may have appeared in poor shape.  But after a few minutes of tuning around  I discovered there WERE DX signals there,  just not as strong as usual.
       There appeared not to be much coming through via high latitude paths.  Even Canadian VE1DT at 1437 GMT spotted on 14012.6 was only S-5.  I had run across him just dropping his call, apparently trying to attract a European that had been working other stations. Maybe the signal strength was just down because he had a yagi pointed away from me, because I eventually heard the station he was working. It was the first Ukraine station of the morning in the contest, UT0U, who as I listened came up from being almost in the noise to S-5.
       From there things proved to be a little easier.  The DX WAS in fact there,  just at a lower level. The band being open was confirmed when I heard N5WX  on 14002.5 at 1442 on backscatter.  The station he was working was another Bulgarian, LZ5R who was also about S-5.
       That proved to be the average signal strength of several Europeans heard over the next couple hours.  I logged several Ukraine stations over that period and many Southern European stations.  Some like HG7A from Hungary were marked by flutter. It would have been easy to give up on the band after a quick initial glance, but sticking with it proved that signals were, in fact, there.
       I would think that tuning SWBC bands would be similar.  For those interested only in their regularly heard programs, there might be disappointment and a temptation to just turn the radio off.  But for the DX-er wanting to put neat stuff in the log,  it might prove to be more an opportunity.  If the band is just open differently than usual,  either longer or shorter or in a different direction for some reason,  it would be an opportunity to log something else that might usually be buried under the "usual suspects" one would normally find there.  Don't give up so easily!
       After our usual family brunch we enjoy on the weekends, it was back to the radio about 1700 GMT.  The WWV sweep showed 2.5 inaudible, 5 with a barely detectable carrier ( not unexpected for nearly midday!) 10 MHz at S-9+ 20 DB but with some fading, 15 MHz at S-9+10 DB with slow fading and with WWVH audible behind it.  Then came the big surprise. The 20 MHz WWV was booming in at S-9 + 30 DB!!!!  Stronger than I had heard it in a long time. I posted such in one of my Facebook groups and right away a couple postings appeared of others in the Northeast US hearing it well, too!  The 25 MHz WWV however, had a just audible carrier.
       The first thought was to check the 15 meter ham band.  There were lots of signals there,  but mostly single hop stuff.  They were very, very strong, however.  I am thinking the MUF must have been right around 21 MHz for those paths.  Many like KD2RC and K6LL were S-9+20 DB.  This was on the R-75 on the 80 meter sloper at 45 feet. 
       One good catch during this time was a PJ6N on Saba Island.  he was heard at 1820 GMT on 21005.2.
       Being curious, I took a look up on ten meters.  I am not sure why, given the fact that the 25 MHz WWV signal was so weak.  But it paid off.  Perhaps the skip on 25 was just a little long for the path to Central Texas because ten was alive! Unfortunately, not with stations working stations,  but the beacons were pouring in.  For those who do not know,  beacons are very low power stations put up by amateurs generally in the area between 28.2 and 28.3 MHz  Most operate with between one and five watts  with Omni-directional antennas designed to be indicators of whether the band is open.  And it was.  First heard at 1830 GMT was N7UTP on 28200.1.
       After that, over a dozen were logged in quick succession,  including 4U1UN at the United Nations club station in New York heard with an S-9 signal on 28200.5 at 1832.
       Interestingly, even though the band appeared open, there was little activity.  Once again, it appeared the "news" about poor prop or predictions of same might have deterred folks from even looking or making more than a cursory tune across the band. There was one island of high activity, however, around  28017.2 where TG9ADM in Guatemala had set up shop.  He soon was working a very busy pileup.
       A quick drop back to fifteen meters around 1900 showed some activity prior to the beginning of the ARRL Sweepstakes contest.  One really good one was found when a good sized pileup of rather weak stations was found  around 21009.  After considerable listening and pulling out one letter at a time, it was determined that at the bottom of the pile was 9Q6AL from the Democratic Republic of the Congo!  Careful listening and diligence pays off!!
       From then on through the afternoon  it was hopscotching between bands and the TV for college football. At 1933,  a new one for me on 17 meters  was VP2MVI from Montserrat on 18072.  Don't know how I had missed that one in the past,  but sometimes that's the way it works.  One that would seem to be a "given" somehow either gets missed or just isn't heard. That filled the line across the tally sheet for Montserrat for all bands 160-10.
       The afternoon on ten meters turned up many South American and Caribbean stations.  The catch of the afternoon for fifteen meters was V51YJ in Namibia  at 2010 on 21012 working a spirited pileup.  Just in time, too because as the Sweepstakes Contest began a little later, the US stations would have pretty well covered any possibility of deep DX, at least on CW.  The rest of the weekend would have to be either on phone or tuning the WARC bands ( 30,17 and 12 meters) which are contest free by convention.      
       Even though the ten meter beacons were still coming in and a beehive of Sweepstakes Contest stations were audible on ten meters,  twelve did not yield much.  Obviously the band was open, because PY3NA was coming through calling CQ on USB  at 2314 GMT on 24945 with a pretty good signal.  The background noise indicated the band was open. 
       I don't know how many of you have noticed the actual " sound" of an open  band.  There is a sound other than that which is locally generated noise that is often heard that can give you the feeling that the lights are on but nobody is home.  I do not know if it is the aggregate noise from other places that props in like other skywave signals or just what it is,  but sometimes you can actually hear it, sometimes even with a little selective fading in it.  In the old days  when cars generated spark plug noise you could sometimes hear the total sum of that adding up to provide a background floor in an open band.
       I had a friend who is now a silent key who spent time in Panama and on Swan Island on work assignments who told of many times hearing Stateside or other ignition noise propping into Swan Island when there were no engines running on the island at all.( Swan Island is very small and off the coast of Honduras. In the 1960's it was the center of some controversy as a supposed location of a station known as Radio Americas that broadcast on 1160 and 6000 KHz carrying anti communist programming aimed at Cuba. That story could almost make a novel by itself!!!!) But I wander afield again...
       While there were few signals present, it was a matter of just finding where the band is open and drop the hook there. In this case, it was back to 17 meters.  As it was getting close to sunset local Central Texas time, the hope was to find some Asian or Pacific stations.  They were indeed there.
       It was a classic late-in-the-day,  upper-band condition.  South American and Japanese stations were showing up in large numbers.  At 2318, I first found PX5Z in Brazil and  JO1WXO from Japan just a kHz apart on 18076 and 18077 respectively.  The dual 250 Hz filters in the R-75 easily separated the two  The pattern remained the same as the band was scanned.. South American stations were running about S-7,  the Japanese stations were running S-5 or lower.  They were not jumping out of the radio by any means,  and if you spun the dial quickly just doing a  "quick cruise" you might miss them.  But slow and careful tuning would turn them up.  In conditions like this,  I often open the selectivity up to " CW wide" or even a narrow SSB position while looking for stations in the grass,  then if I find a group of stations, THEN tighten things up and gingerly turn the dial to pick out the goodies.  Over the next half hour I filled almost a complete page with callsigns on an afternoon when " the bands are crummy"!
       The one that would have been missed if I had just given up and said " oh there's nothing here" was found at 2334 on 17 meter sideband,  one that would be good in anyone's logbook: VP8LP in the Falkland Islands  on 18155 working a fair sized pile.  Interestingly many of the stations he was hearing and working were inaudible here..
       After dinner, one more check of the bands were made before a little family time. As is often the case,  the upper bands sounding bad were an indication that the lower bands would be fine.  Eighty meters handed up EA8ZS with a fair signal even through the evening static crashes and Sweepstakes Contesers  on 3515 at 0203 GMT on the " next day" GMT though it was of course, evening in Texas.
       Sunday was going to have short time for listening because of an impending visit by grandbabies
and playing of a different sort!.  I got on for a few minutes at 1200 GMT or 6 AM local time and fired up the R-75.  The WWV  sweep showed 2.5 MHz WWV  at S-9+30 DB, CHU on 3330 at S-7, WWV on 5.0 at S-9+40 DB(!!) with WWVH well audible behind it.  On 10 MHz, WWVH was again on top about S-5 with lots of QSB and WWV inaudible.  There was nothing audible,  not even detectable carriers on 15, 20, or 25 MHz.
       Someone had mentioned on Facebook  FEBA from their Philippines Manila site coming in to England, so I made a quick check there.  They were S-7 on 9400 and S-5 on 9430,  the opposite being stronger I Texas  than in England where the poster had shown 9430 to be the stronger of the two.  Thirty-one meters is always interesting and surprising around sunrise and sunset.  This was an interesting logging in particular because he was most probably hearing the signals coming to his location from the East  while I was most probably hearing them  coming from my West!  This is one of the little observations that makes this hobby fun.
       With the little time I had left, I dropped to the "basement " of the HF range and checked for the Northern Australian signals. VL8T on 2325 from Tennant Creek was S-4 but actually readable on a morning where the noise was very low here. Its band mate VL8K on 2485 was  stronger at S-7.  I remember wondering if there was that much difference in prop over 160 kHz or if there was some difference in the characteristics of their transmitting antennas.
       Up the band a bit at 2850 Pyongyang, North Korea was rolling in at S-9, better than its transmitters on 3220 and 3320 which were about S-5.
       One thing I miss from these morning sweeps is the old HCJB signal that held down 3220 for so many years with its local  language programs. I guess times change, but the loss of their facilities in Ecuador marks a change I could have done without!
        The Voice of the People from the other side of the Korean DMZ was coming in well on 3480 and 3912, along with its jamming counterparts.
       The last loggings of the morning and of the weekend was Radio Nikkei on 3925 which was an amazing S-9+10db and sounding good.  The last logging was actually a  " no log" as it appeared, and was noted in the log,  that Radio Nikkei on 3945 appeared to be missing!
       It was not too bad for a weekend that so many folks had moaned about as being poor! I had chosen to spend most of the time in the ham bands because of uncertainty about schedule info being updated for the broadcast stations,  but it might have been a good time to confirm what I believe about band conditions.  Often when the "regulars" are not heard,  it is not because the band is dead,  but because it is open to somewhere else.  The band may be longer or shorter than usual. There may be other things to hear in the absence of the regulars. Or there might be other targets to be sought out on other bands.   Often the WWV sweeps can tell you things about that.  For those on other continents where WWV and WWVH might not be useful as "prop" beacons, there might be other stations you can use as barometers...maybe even other time and frequency standards or stations that you regularly hear at certain times.  Checking the barometers can often save you time and tell you where to drop the hook to find the fish!
       For those listening mostly for programming,  it might be a time to find other programs that you do not usually hear.  For the DX-er,  its  often a golden opportunity to hunt for new things on new bands. It is not a time to give up and default to the TV. There are enough differences in conditions on the different bands stretching from LF to 30 MHz that there is always something to be found  to put into a log!
         Good hunting!

        

Crystal Filters and Phasing

       While looking at older receivers for SWL DX purposes, there are a few features that are particularly helpful.  After the usual  " default " requirements of at least one tuned RF amplifier stage and at least two IF amplifier stages comes some means of tightening selectivity.
       When it gets down to it, almost all boat anchor receivers that have two IF stages with a 455 kHz Intermediate Frequency  ( which covers about 95% of those built in the 50's, 60's and 70's) the selectivity of all of them are pretty much equal. About all you can count on is about 10 kHz selectivity without some kind of additional selectivity enhancement.  This is not to say that two broadcast stations 5 kHz apart could not be identified, but that if one was particularly stronger than the other, there would be considerable  "slop" between the two of them and listening would not be comfortable. CW reception on the amateur bands would be possible but digging out the real DX would be difficult because of interference from neighboring stronger signals.
       We have covered the Q multiplier in a previous post.  The next selectivity enhancing feature is the crystal filter.  This was considered a significant expense to add to receivers in that time period and would boost the price considerably. Now because of collectors looking for even the lower level, or entry level receivers, things have kind of evened out.
       The simplest form of crystal filter consists of one crystal cut for the Intermediate Frequency and at some point in the IF chain in series with the signal path. The crystal will pass frequencies on its frequency fairly well, with response falling off rapidly on either side of its resonant frequency.
       The peak on a single, simple crystal filter is fairly sharp. The center frequency is the resonant frequency with response falling off in a curve.  The selectivity figures for receivers are usually referred to in how many DB down the signal is from the resonant frequency.  The points usually used are 6  DB down and 60 DB down.  The difference between the two gives some idea of the sharpness of the filter or tuned circuits in the radio. The 6 DB down figure indicates the frequency separation at which the signal strength is half what it is on the peak. The 60 DB down figure indicates the frequency separation at which all but the strongest signal would be practically gone.
       A graph of the response can be either very "pointed' or sharp, or slope down gently.  The lower parts of the curve are referred to as the "skirts".  The closer in the skirts as the response goes down, the sharper the selectivity.
       More complex filters can be built to shape that response.  These filters make use of more than one crystal and are sometimes referred to as " crystal lattice" filters or  " multi pole" filters.   The purpose of the filter determines how the lattice is set up.  A filter designed predominantly for cw operation might be made up of crystals very close in frequency to give a very sharp, narrow filter with steep skirts. There might be a design that leaves the top a little flat to avoid ringing in the filter.
       A multi pole filter designed for Single Side Band or AM might be made quite differently.  It would be made of several crystals spaced in frequency to give a fairly flat topped response over a 2.5 to perhaps 6 or 8 kHz bandwidth to allow the sidebands of the SSB signal or AM signal to be passed without muffling the sound.  At the same time, the multiplicity of crystals will also insure very steep skirts outside the desired passband. These kinds of filters are often optional filters and are usually found in more complex, communications grade receivers.  They are also very expensive!!
      If you are lucky enough to have a receiver with positions or sockets for optional filters, such as the Icom R-75 or others,  you may have a choice of purchasing filters made by the receiver manufacturer or other after market filters made by other companies.  When looking at the information for these filters,  you will often find charts and graphs that illustrate the responses of the various models of filter.  Careful study should be given to these graphs with thought toward what kind of listening you plan to do.  Casual listening to AM signals on shortwave broadcast bands or Medium Wave might call for a slightly wider bandwidth while serious DX-in and digging for weaker signals might call for something sharper. But once again, I am wandering a bit from the central subject!
       Most common boat anchor receivers have the more simple, single crystal filters. The question sometimes is, which ones have them and which ones don't.  With Hallicrafters,  this is easy.  The receivers without filters have a model number with just the "S" and a number,  such as S-118,  S-120, S-85, S-38, S-40B etc.  The receivers with the filters have an "X" in the model number,  such as
SX-62, SX-71, SX-96,  SX-99, SX-100, etc.  With the others, its a matter of looking them up.
       When looking at a receiver,  it is often easy to tell by reading labels on controls.  If there is a selectivity switch with multiple positions,  its a pretty good clue.  If there is a control labeled crystal phasing" or just " phasing" it is a certainty! 
         Using a crystal filter is a little easier than using a Q multiplier, but there are some things to know beyond just turning it on or setting to a tighter selectivity position.  The phasing control affects its operation by in some ways bypassing it partially and in some ways shifting its peak and null frequency a little.  Some folks get the idea its like a passband tuning control,  and while it may act a little like that, it is not exactly what is going on.\
       While the crystal filter has a passband narrower than the bare IF amplifier, it also has some nulls and secondary peaks off the main frequency.  The phasing control affects them somewhat.  If you are tuning casually on AM,  I find it useful  to have it set off to one side a bit. Then when a station is encountered that you are interested in, rotate the phasing control back and forth to get the best response. You might find that one of the off peak nulls might just take out a pesky heterodyne, though it may affect the desired signal a bit.
       A good thing to do when first obtaining a receiver with a crystal filter is to conduct  a little "experiment and training" session.  If you get a manual with the receiver, there will probably be a general discussion of the operation of the various controls including the crystal filter. There may even be a graphic representation of the crystal's response.  This can be helpful if you can picture what is happening as you are tuning and trying to get the filter to help you.
       As part of the "experiment and training" session, the best thing to do is find a good, steady signal, preferably a not-too-local broadcast band station.  If the receiver has an S-meter, you can get a really good picture of what is going on. 
       First tune the station in with the crystal filter "out" or selectivity control in the broadest position. Peak the signal carefully with the receiver tuning control.  Then switch the filter in or go to the next tighter position.  You might actually see the signal strength drop a bit.  Depending on the alignment condition of the receiver and the insertion loss of the filter, it might drop a little or it could drop a lot.  All crystal filters have some insertion loss and its not unusual to see a drop of an S-unit or two even on those in the best condition.
       Turn the phasing control back and forth and see if the signal peaks up or drops down.  If it peaks, set the phasing control for maximum signal.  Then carefully rock the tuning dial back and forth and see if you can get any more out of it.  Go back and forth a few times to make sure you have it at its highest. Note the position of the phasing control for future reference.  This will be the position you will want it in while you are in the general "hunt" mode for AM or broadcast stations.
       Next watch the S-meter and tune the dial off the station, then slowly go across it to center and beyond.  Note the actions of the S-meter.  There should be the one main peak, some dips and maybe a minor peak again, probably just on one side.  These filters are not usually perfectly symmetrical,  with the symmetry somewhat affected by the position of the phasing control.
       This exercise will give you some idea of the basic shape of the passband of the filter.it will also give you the best starting point while tuning.
       After noting the best " center" position for the phasing control, center the station up well and move the phasing control back and forth, noting the actions of the s-meter.  This will give you some feel for the shape or impact the control can have when you may need it.
       Some users of these radios will come away with the idea that the crystal filter is of no use or help or has no effect.  Going through this little exercise should cure that notion.  Often those who get that impression are just turning knobs aimlessly and don't get much of an effect simply because the randomness does not take them into an area where the effect can be seen!    
       The crystal filter can really help out on CW and SSB.  To set up for CW tune to a quiet place or disconnect the antenna.  Put the selective switch in the narrowest position. Turn the phasing control off to one side or extreme range of its setting.Turn on the Beat Frequency Oscillator or set the radio in the "CW" mode. Rotate the BFO pitch control back and forth, listening for a light "swishing" sound as it moves through the receiver passband.  Find the lowest pitch spot which should indicate the center of the passband.  Note this position.  Hopefully,  if the receiver does not need a serious realignment, it will be near the center of the travel of the control. Remember this position for future use. Now offset the pitch control one way or the other just slightly from that center position so that it is toward one side of the center of the  passband. Turn off the BFO.
       Now with the antenna reconnected, tune in a steady AM carrier, preferably a medium wave station within groundwave range but one not too strong. Center it up in the passband by either watching the S-meter or listening for the slight swishing sound that sort of "bottoms out" as you get it centered. The selectivity switch if there is one should be in the narrow, or if there are multiple settings, in the narrowest position.
          Turn on the BFO.  Rotate the pitch control back and forth, finding the zero-beat position over the carrier you have tuned in.  It should be near or at the spot where you had centered it earlier if your tuning has been careful.  Now offset the pitch control slightly giving a heterodyne of a pitch that would be comfortable copying CW for you.
       A short aside here: Normally I would say to set up for copying with a low pitch.  However, with simple crystal filters anything much lower than 800-1000 Hz might put the signal on the " other side of zero beat" too close to allow what is known as single signal reception.  After you finish this set up you can experiment with what pitches give the best compromise between copying at a low pitch and selectivity.
       Now leaving the pitch control in the same spot, using the receiver tuning, tune back to zero beat and on to the other side where the pitch comes back up to about the same pitch as you had when you set the BFO.  Now adjust the crystal phasing control for minimum signal or lowest indication on the S-meter.
       Once this is done, with the receiver tuning, go back through zero beat and take a look at the signal strength of the desired signal.   It should be significantly higher than the nulled side.  With some receivers, this may take a little juggling of the pitch control, offset and phasing adjustment to get the effect you want...as close to single signal reception of  CW as you can get.  Finding the " sweet spots" sometimes takes a bit of experimentation,  but once you have found them, you will find that you are getting the maximum effect out of your crystal filter and can most easily separate CW stations on a crowded band!  Once again, the "art" of tuning comes into play and this is another example of operator skills that can be developed to get the most out of any receiver.
       For SSB, once again turn the BFO pitch "off".  You will find that there will need to be different settings for  BFO pitch and crystal phasing for Upper Sideband ( USB) and Lower Sideband ( LSB).
In each case you will want to have the desired signal centered in the receiver passband but because of the nature of needing to have the missing carrier re-injected in different places to make the SSB signals audible you will need to have the BFO pitch control set differently for the two modes.  And to have the crystals peak and null features in the right spot, there will need to be different settings of the phasing control for the two modes as well.
       Fortunately, finding signals that are definitely known to be USB and LSB is easy.  By convention in the amateur bands, operation on 160, 80, and 40 meters is on LSB while operation on 20,17,15,12,10 and 6 meters is on USB ( there is no phone operation on 30 meters).
       Once again turn the BFO " off " or set the receiver into the AM mode.  Tune in a signal on one of the bands where LSB is used and pick out a signal that is kind of by itself to make set up easier.  You will not be able to understand the talk at this point, but as best you can, center the signal up in the passband.  Selectivity should be in the "narrow" position if there are just " wide" and "narrow" positions or in one of the mid selectivity positions if there are multiple selections.  Set the crystal phasing control off to one side or extreme.
       Turn on the BFO and rotate the pitch control until the signal becomes intelligible or sounds most natural. If the signal is really strong, you might have to back off on the RF gain or sensitivity control on some receivers.
       A this point there needs to be another aside.  If during your initial CW set up you found that the BFO hit the center of the passband well off center of its range, the receiver may be slightly out of alignment and you might not be able to get the control " far enough over " to reach the intelligibility spot.  If such is the case, its ok to "cheat" a little and move the receiver tuning slightly to hit the spot. At some point a receiver alignment would help this situation out, but most basic crystal filters are not so super selective as to make tuning in the signals with a little "cheating" impossible.
       Once the signal is intelligible and the sound is comfortable to hear, use the receiver tuning to move the signal through the passband, going toward the zero beat or in the direction that makes the voice lower pitched until you are on the " other side " of it and it is unintelligible. Make sure you are completely on the " other side" and are hearing the signal effectively " upside down".  At this point, adjust the phasing control for minimum signal.  Then take the receiver tuning control back through zero beat and to the position where your signal is intelligible. It should still be readable and not too reduced in signal strength.  As with the adjustment for CW, there might need to be a little jockeying of the positions of tuning,  BFO pitch and crystal phasing,  but with a little experimentation you can find the settings that will give maximum intelligibility and selectivity.  Note the positions of the BFO pitch and phasing controls and when you start looking for LSB signals, preset them to those positions and you will find your initial search for signals much easier.
       Now go to a band where you know USB signals are located and repeat the process.  Again, note the positions of the controls for future reference.  You will find that the BFO pitch control is at the opposite end of its range from where it ended up for LSB signals. 
       Again, every receiver is a little different,  every crystal is a little different and every receiver alignment condition is a little different.  It take patience and practice, practice, practice to get to the optimum settings.  These initial settings will get you " into the ballpark" and you may find slightly different settings as you further learn your radio. Under certain QRM conditions you might find yourself playing with the controls a bit to hear the station you want.  But always going to these initial settings will save you a lot of time and prevent simple "flailing in the dark" trying to tune a signal in and generating a lot of frustration.  I cannot over-emphasize the existence of a real art to tuning in DX!!
       One other note about tuning SSB signals on older boat anchor receivers.  Many were built before what are know as "product detectors" were routinely put in radios.  In  fact,  many were built before SSB was routinely used in amateur bands and was predominately found in commercial point-to-point operations. They were not designed for optimum SSB operation.  That does not mean they cannot do an admirable job in copying SSB signals.  It DOES mean that some additional care will be needed to make it possible.
       If there is difficulty in getting the SSB signal fully intelligible even when you hit the position where the pitches appear right,  back off on the RF gain or sensitivity control.  It may be that the signal is too strong for the BFO injection level of your receiver.  Tuning SSB signals with these receivers sometimes requires more frequent adjustment of RF gain to make it work out.
       By the way,  the description of tuning in SSB signals with a BFO pitch control outline above also applies to the newer portables that can copy SSB.  The method up to the point of adjusting the crystal phasing should be the same to avoid some wild-eyed frustration in getting the signals audible.  For those portables with pitch controls or an equivalent there-of  the method outlined will help considerably.
       One other note about crystal filters and receiver alignment.  Because crystals can "wander" somewhat with age and because quality control may not have been the best with some manufacturers, the crystal may not be centered exactly on 455 kHz ( or what ever the design Intermediate Frequency of the receiver might be).  For this reason,  when doing an alignment of these receivers it is highly important that a signal generator be fed into the IF's before the filter, meaning in some cases may need to be fed into one of the grids of the mixer tube.  It also means that instead of arbitrarily setting the signal generator at 455 that it be swept slightly back and forth two or three kHz to find the peak of the crystal ( with the phasing control off to one side or extreme) and aligning the IF to the crystal. The difference of one or two kHz will not be enough to affect the tracking and calibration of the main tuning.  The important thing is that the Intermediate Frequency amplifiers be peaked to the frequency of the crystal because that will keep the narrowest response possible.  The frequency of the IF peak can be shifted a little, but the response peak of the crystal cannot!
      One other note about alignment at this point that applies to any boat anchor regardless of whether it has a crystal filter:  Once alignment has been complete, turn on the BFO and swing it through its range with the signal generator still feeding at IF signal in.  You should always have the signal generator output level set at the lowest setting possible to allow alignment.  Rotate the BFO pitch control for zero beat against the signal generator carrier.  Note if the BFO pitch control is at the center of its range.  If it is not,  look in the service materials for the receiver and find a below chassis adjustment for the BFO frequency.  It will probably be a slug tuned coil.  Once you find it, set the BFO pitch control on the front panel to the center of its range, then bring the BFO frequency to zero beat with the other adjustment.
       Older receivers with crystal filters are not all exactly the same,  but the principal of the operation is. There are still differences in quality of components and even of the crystals themselves.  The single crystal filter may not be as tight as some of the multi pole filters that appear in the more expensive radios,  but they do tend to be more effective than some of the ceramic filters that appear in some of today's budget portables.
       Once again, I will note that the methods described here are not to be taken as " the only way" to do things,  but are the methods I personally have found useful in fifty plus years of spinning the dials.  They work well for me and have put 326 countries in the log.
       For those who enjoy tuning with the vintage receivers and capturing some of the adventure of the golden age of SWL,  a crystal filter equipped radio will provide the additional satisfaction of greatly improved selectivity. There is something special about tuning one of these "beasts" though for a beginner, there are many things to learn and some  frustrations to avoid.  They are not necessarily for the " dial in the frequency and forget it and listen " crowd. For that group, even the most expensive, digital dial and DSP equipped radio might be found to be frustrating for them.  But for others seeking a bit of adventure from the hobby the boat anchors do offer a level of performance and sound quality that is difficult for many of the inexpensive portables to match. DX-ing, like life in general, offers a bit more to those willing to put a bit more into it ( a little personal philosophy there, too!!)
       Whatever type receiver you chose to use, the important thing is to learn how to use it to the fullest of its capabilities.  Tuning shortwave is not like turning on your cable-fed television and dialing to a channel number and having a station pop up!
       Good DX.  Good Hunting!

Boat Anchors and Q- Multipliers

       There can be lots of arguments about whether its better to use one of the new high tech radios for SWL or BCB DX-ing or whether to go with a more complex table top model. My own experience has been that the table top unit gives better performance for digging out deep-buried DX but that a high tech portable in the hands of a skillful user can do very well.  On the other hand, to get the most out of the table top radio also requires a certain amount of skill and getting to know the radio.
       The new portables particularly have the advantage of providing much better frequency readout than many of the old desk top "boat anchors" could provide,  while the older receivers can often provide more robust handling of very strong signals and deal better with connection with outdoor antennas.
       The older rigs can also provide better selectivity than the new portables.  They do this through the use of crystal filters and in some cases Q-Multipliers.
       The issue of Q-multipliers came up on a Facebook Group of which I am a member this week and questions about its use and "whether it was working or doing anything" resulted in a short note to the poster describing the use of the device in a rather abbreviated way.  I thought perhaps sharing a more detailed information about their operation and use might be in order here.
       Just what is a Q-Multiplier?  Well the abbreviation "Q" in the electronic sense refers to the "Quality Factor" of an inductor or tuned circuit.  Without getting into the esoteric details, what it boils down to is it generally can refer to selectivity or how broadband a device might be.  A tuned circuit or antenna with a High Q would have a narrower bandwidth whereas a tuned circuit or antenna with a Low Q would tend to be rather more broadband.  There are many factors that go into determining the Q of a coil or antenna.  In the case of coils,  wire diameter, turn spacing, diameter of the coil winding and resistance of the wire or surrounding circuit are the major factors, along with any loading on the circuit.  The bandwidth of antennas is a whole other issue that could take up its own entire article!
       The name " Q-multiplier" then can almost be surmised as being a device that somehow "multiplies the Q" of a circuit or in this case, does something that increases its selectivity.  In superheterodyne receivers,  the real selectivity takes place in the Intermediate Frequency amplifiers.  The superhet design basically converts all incoming signals down to one frequency where high gain, stable amplifiers are easier to design to operate in a fixed-tune mode.  The concept as created in the 1920's and 30's has remained with us ever since.
       Different boat anchor designs, just like different new portable designs, came with different price tags depending on the complexity of the circuits and the cost of the components placed in them.  The basic design that is of most use to DX-ers is one that has at least one stage of tuned radio frequency amplification (  one R.F. Stage) and two stages of Intermediate Frequency amplification ( two I.F. stages) Most single conversion radios had a 455 kHz IF.  Some dual conversion radios had a 1650 kHz  First IF and 455 kHz Second IF.  The triple conversion receivers often made a further conversion to 50 kHz.
        Q multipliers have been around since the very creation of the superhet design as a means of improving selectivity in the Intermediate Frequency stages.  It basically brings the advantage of a regenerative receiver to add to the greater advantages of the superhet design  it had been determined earlier that the use of feedback or regeneration in an amplifier stage would artificially increase its Q by overcoming losses in the circuit. A small portion of the output would be coupled back to the input at a level just below that which would cause oscillation. 
       This can actually be done in the IF stage itself to a degree but is difficult to control because of the action of the Automatic Gain Control circuits.  When the gain goes up in the absence of a signal,the stage is pushed more toward oscillation. If the internal feedback is set at this level,  it does not do much good when the gain of the stage is then pushed down by the presence of one or more stronger signals, which is the exact time more regeneration is needed.
       The device covered by the term Q multiplier generally refers to what amounts to a separate IF amplifier operating in parallel with those existing in the receiver. It is often connected to either the plate of the last converter tube if there is but a single IF stage or the plate of the first IF amplifier stage if there is more than one.  It must be tuned to the same IF frequency as that of the receiver to which it is attached.  For the " add-on" devices this was most frequently 455 kHz.
       I am not sure if anyone knows who first published designs for outboard Q multipliers or extra circuits of one built into a receiver but they have been around for a long time.  They were also around in abundance as add-ons in the form of kits in the 50's and 60's,  most notably the Heathkit QF-1 and its descendants. Some receivers,  including many of the general coverage Heathkits had jacks on the back to allow easy connection of the Q-multiplier.
       There are also many construction articles on how to build one and connect it to a receiver in the archives of many magazines such as QST,  CQ, Popular Electronics and Electronics Illustrated.  Older editions of the Radio Amateur's Handbook published by the American Radio Relay League also have information on the theory, design and actual construction and connection of them.  I am sure the same goes for Radio Society of Great Britain and organizations in other countries.  Most of these articles and designs tell of how power to operate Q-multipliers may be taken from the receivers to which they are to be connected and how to set them up.  Others may be built with their own internal power supplies.
       Using the devices is a bit of a learned art,  much as the actual tuning of a receiver is such.  While instruction may be given, there is nothing like the "hands on" practice of making them work to get the most out of them.
       Most Q multipliers have the same minimum controls: Tuning and some form of gain control.  It might be labeled " selectivity" or in the case of the Drake Q multiplier meant to be used with the famous 2B receiver it is called " Q balance".  Some many have additional controls to chose between peaking and notching signals.  The Heath also had a "Broad" and " Narrow" switch.  Some radios with built in Q multipliers may not have the tuning control.
       I will leave the adding and/or building of  a Q multiplier to other articles.  Here I will cover the operation and use of one. 
       The first thing to do is turn the device on and set the "gain","selectivity" or whatever form the operating level control might be to about mid scale. Start with the radio in the AM mode and tuned to a quiet spot or with the antenna disconnected.  Then  rock the Q multiplier tuning control back and forth and listen for a "swishing" sound.  If you don't hear one, run the "selectivity" control up a bit more ( clockwise) until you do.  Note where on the tuning control the "swish" seems to have the lowest pitch or sounds like it is " bottoming out".  This will be the spot that corresponds to the center of the receiver's passband.  Note that spot for future reference.  Depending on the alignment of the receiver and the Q multiplier,  this might not necessarily be at the center of the control's travel.  This can be corrected but should not be attempted without proper understanding of the receiver and Q multiplier circuit operation.  In no instance should an attempt be made to realign the IF stages without a signal generator of known frequency calibration or proper calibration and tracking of tuning on the main tuning dial can be negatively affected!!
         For tuning AM signals,  it is best to start with the Q multiplier tuning set in the center of the passband.  Once the signal is tuned in and centered, you can try swinging the tuning back and forth to get the best readability without slicing too much off the sidebands.  If the selectivity is too tight, all the highs will be sliced off and the station will sound muffled.  You can try tuning off to one side or the other with the Q multiplier tuning which can act much like passband tuning.
        If there is a strong heterodyne or splatter interference on one side you can try tuning the station in with the main tuning placing its carrier on the edge of the passband placing the splatter farthest from the center, with the desired side centered in the passband.  Then crank up the Q multiplier and make adjustments with its tuning.
        This is where the art of using the device comes in.  It is only with practice and patience that the full effects and possibilities of this device can be learned and attained.
       It is on cw and single sideband that the Q multiplier can really show its maximum potential. There are probably a number of " set up " methods for cw reception with one, but here I will describe the one I have used and found to be one that at least works for me!
       The first method involves a receiver with a variable pitch BFO. The first step is very similar to that with which the Q multiplier tuning is determined.  Tune the receiver to a quiet spot or disconnect the antenna.  Turn on the receiver's BFO ( Beat Frequency Oscillator) and rock the pitch control back and forth.  you will hear the "swish" similar to what was heard with the Q multiplier tune set up.  Once again the "swish" will " bottom out" or have a noticeable lower pitch when it is moved through the center of the passband.  This is, of course, not where you really want it...it is where you want the desired signal to be, so at this point move the pitch control a slight amount to the right or left ( as you turn the knob) from center.
       For practice,  connect the antenna and tune in an AM signal that is not too strong, but which is of a fairly steady strength.  Probably the best place and time to do this is in the daytime with an AM broadcast station other than a powerhouse local station. If your receiver has an S-meter. carefully center it up for the maximum meter indication.  If you have no S-meter, by ear rock the tuning back and forth and with practice on a weaker signal you can hear when the signal is centered.  If the receiver has fairly good selectivity to begin with you can hear the little " swish" as the carrier moves through the passband or you can hear the lessening of the high frequency sounds on the sidebands as its is centered.
       Again, this ability to notice things comes with practice.  The accurate and careful tuning of a receiver is much more than just dialing the tuning to a spot and finding something.  There are a number of subtleties that can be recognized only with practice and that are often  hard to describe in words.  The receiver cannot do the work for you, no matter how complex or expensive it may be. I think I have noted  before that a skillful operator can pull out DX with a simple receiver that a casual tuner cannot find with a much more expensive one. Practice, practice, practice and learn to take advantages of the capabilities and avoid the weaknesses or your receiver!
       But I digress.  Once you have your " test signal" tuned in,  turn on the BFO and rock the pitch control back and forth.  Listen for where the " Zero Beat" occurs,.  The zero beat definition will be obvious as you do this.  It is the point at which the pitch of the heterodyne of the beat frequency oscillator goes lower and lower in pitch and at one point becomes "zero".
       Note again where the zero beat occurs on the pitch control.  If your tuning has been careful, you should notice that it is at or very near the same spot as you noticed the lowest pitch " swish" when rocking it when listening to no signal.
       At this point, leave the receiver tuning alone and move the pitch control  to one side of zero beat  or the other to obtain a pitch comfortable for you to listen to cw. Then turn the Q multiplier on and set the selectivity control fairly high.  If there is a "peak-notch" or " peak-null" switch, set it to peak.  Now move the Q multiplier tuning control to peak the level of the resulting beat note. Or watch the S meter for a peak.  Run the selectivity control as high as you can without the device going into oscillation itself.  If you keep it right on the ragged edge of oscillation you will be at the tightest selectivity point. 
       Now to test if your adjustment has been good, move the receiver tuning control back through zero beat and back up the other side.  If the Q multiplier is doing its job and your adjustments have been proper you should notice that as you tune to the other side of zero beat,  the signal should be much weaker.  In other words,  on one side of zero beat you will have a strong signal and on the other side of zero beat it should be much lower.  The idea is to have the BFO injection offset in the receiver passband to make any signal that would have the same pitch as your desired signal to be out of the passband on the other side of zero beat.
       This results in what is called " single signal" cw reception. Otherwise, as you tune through a crowded band, each signal will actually show up twice, resulting in effectively  an undesired signal giving QRM to a signal that you might otherwise hear from the other side of zero beat.  Effective set up of BFO pitch and Q multiplier tuning can thus for all practical purposes doubled the tightness of selectivity of the receiver! The ability to bring this about effectively comes only with practice.  It is best done listening to a good steady carrier and doing the set up over and over and finding the best settings for your particular receiver.
       Tuning in single sideband signals is a bit more complex.  Without the Q multiplier on,  tune in a good fairly steady SSB signal and practice making it intelligible. Once again, start with the BFO offset to one side or the other of the center of passband.  This is why you want to remember or note the position of the control at dead center zero beat.  You want to have the desired SSB signal centered in the passband and the BFO injected on a frequency offset and near the edge of the passband.  Just as with single signal cw reception, you will eliminate QRM coming from " the other side" of the BFO.
       The trick is the required position of the BFO pitch control is different for upper sideband ( USB) signals and lower sideband ( LSB) signals.  This, again, will take practice to determine.  One thing that makes it a little easier is the fact that by convention, on the amateur bands, everyone operates lower sideband ( LSB) on 160, 80, and 40 meters  and upper sideband ( USB)  on 20, 15,17,15,12 and 10 meters.( there is no phone operation on 30 meters).
       Once you have a known LSB signal tuned in, juggle your dial tuning and BFO pitch to obtained the best overall intelligibility and note the position of the BFO pitch control.  Then turn on the Q multiplier and starting with the selectivity control somewhat lower than for CW, adjust the Q multiplier tuning for most intelligible or strongest signal and run the selectivity control up until it starts to "bite" into the high frequencies of the voices and begins to make them sound muffled.  Note the positions of the controls so you can always come back to them.
         Then do the same with an upper sideband signal.  Note those control positions.  As you listen more and more, you may refine them somewhat.  Note that the conventions for USB and LSB apply only to the amateur bands.  While tuning in military or other utility stations you will have to make s determination of which sideband they are using. Most often aviation related stuff appears to almost always be on USB, as does military ops,  but you never know....
       With more advanced receivers,  there may be a fixed tuned BFO that makes all this a little easier. Some receivers have function switches with USB and LSB that do all that BFO presetting for you. Then all you have to do is peak and tune the Q multiplier to tighten things up.
       If you have a Q multiplier that has the " Notch", "Null" or "Reject " position,  it will provide you with the ability to eliminate on possible source of interference, such as a strong heterodyne very close to the desired frequency.  Tuning is pretty intuitive. Switch to "null" or whatever it is called with your unit, run the selectivity up and tune the Q multiplier tuning to get rid of the undesired signal.  The downside of this is you lose the ability to tighten up the overall selectivity of the set up.  For this reason I have rarely used the null feature.  I am sure there are times that it might be useful.
       This is only a very basic primer on Q multiplier operation.  As in tuning any other portion of a receiver,  it takes practice, practice, practice. Particularly with adjustments for single signal cw operation use of a steady carrier from a standard broadcast station is handy in that it provides a good, stable test signal.  For SSB,  you pretty much have to work with the real thing.  The thing to remember is to get the desired signal in the middle of the passband and set up the BFO to give maximum intelligibility with BFO injection near one edge or the other of the passband.
       The most effective Q multiplier/receiver combination I have ever seen is that of the old Drake 2B used with the Drake 2BQ Q multiplier.  I have had one for over fifty years and have learned to set it up on cw such that a signal on the other side of zero beat simply does not exist.
       The Q multiplier is one device or feature available on some of the older receivers or that might be added. There are also crystal calibrators and preselectors or preamps...we will look at them at another time!
       Good hunting!

     

          

Books, Books, Books

       Almost all SWL and Ham shacks have a collection of books that accumulate over the years.  I have recently gone through and given my collection a bit of a "haircut" because desk space was becoming limited and some, quite honestly, had not been opened in years. There is some merit in keeping books for historical sense and some for sentimental reasons, but sometimes it gets to be a bit much.  Some I simply boxed away,  like dozens of old World Radio TV Handbooks that might be of some reference value later, but were just taking up too much room on the shelf.  Others have been shared with younger listeners and hams in the area who might learn from them.
       But some simply must be kept. High on the list was the very first WRTH I ever had.  It was actually a Christmas present from my grandparents.

       This marked a true turning point in DX-ing for me because I had for the first time a list of stations other than those in the magazine columns to help me identify stations other than those on the broadcast band.
       Other books that have kept a spot on the shelf include many connected with my career in broadcasting and in amateur radio.  Others were obtained to simply learn things or to assist in making repairs to the many radios that crossed my desk as soon as relatives learned I was " playing" with the things.
       Engineering books often have good application to hobbies and vice versa. There have been times I have used information from the ARRL Antenna book or the Radio Amateurs Handbook in dealing with problems or designs for projects at broadcast sites.  And there have been times that I have used data from the old RCA Antenna Engineering Handbook for amateur antennas in small spaces.
       There is of course a move to having more and more books in electronic form.  This has its place and one of them is allowing one to keep a larger number of texts in a smaller space. It might also allow some of us to find titles that might otherwise be out of print.  But sometimes its good to have an old fashioned book in your lap and to turn the pages.
       In any event, whether its full sized books or collections of magazines with radio articles in them,  they do find a place in the shack along with the radios!

 

 

 

 

 

 

New Shack Arrangment

       After room repairs necessitated by a broken water pipe, there have been some changes to the main operating position.  The primary receivers on the lower two rows are the Hallicrafters SX-96 which is very useful for SWBC and BCB DX work To its right is the Hallicrafters SX-111 which is excellent on the amateur bands with great bandspread for an analog receiver and really sharp selectivity with its 50 kilohertz final IF. Because the receiver has a band position for receiving the 10 MHz WWV,  with the bandspread available it also provides excellent coverage of the 31 meter SWBC band.

       On the lower row on the left is the Yaesu FT-757-GX with narrow SSB filters that also operate in the AM position and 300 hz CW filter.  Then comes the Icom R-75 with 250 Hz cw filters in both IF's and mod for 4 kHz filter that operates in the open or AM position.
       To the far right is my old DX standby for over fifty years,  the Drake 2B with  2BQ Q-multiplier.
This is a triple conversion receiver with 50 kHz final IF that with the Q-multiplier in operation can really slice! With aux crystal positions filled and using the 40 meter amateur position and one of the ten meter positions filled with a substitute crystal, it can receive SWBC on 60, 49, 41, 31, 25,19 and 16 meters. Even with the analog dial it can provide frequency readout easily to 1 kHz.

Medium Wave Seasons Change

       We have now passed the Autumnal Equinox.  Days are getting shorter and nights are getting longer in the Northern Hemisphere,  with the opposite happening in the Southern Hemisphere. September 21-22 will mark the equal length days and nights.  The hours of grey line prop are changing and for some of us, the hours of optimum prop are shifting through our days.
       My time traveling to work is now right at sunrise local time. that means my "mobile DX targets" are becoming available again.  In the U-S where many  Medium Wave stations change power and directional antenna patterns between day and night interesting things can happen.
       While power and pattern change times are supposedly adjusted for the " worst case" interference possibilities, there is some averaging.  That means that toward the end of the months in which days are getting shorter, there will be some days when stations are still switching to daytime power while some night time prop is going on. That means the opportunity to hear some stations not usually heard.
       At the beginning of a month, there is also another opportunity brought about by errors.  Often stations are set up to change power and pattern by timer rather than human switching.  If, on the first of the month,  someone hasn't reset a timer, power change might come at the time set for the previous month and a few stations may end up on high power or day directional pattern while night prop characteristics are in place.  Sometimes if the duty of power and pattern change is left to a morning disk jockey or news announcer,  that person might forget about change times coming later and manually change early.  While this may result in fifteen minutes or a half hour interference to some stations, it will provide DX opportunities to the alert tuner of the dials.
       As these " new signals" appear on the band in the mornings, something else swill be noticed that might not be apparent while tuning the Medium Waves when it is already well dark.  Signals at the top of the band will be propping better than those at the bottom. One might not think that there would be that much difference for signals relatively close together in frequency,  but when one looks at the percentage of the bandwidth over the frequency itself,  the situation becomes more apparent. A 500 kHz spread in frequency over a band at 15 MHz might be only a small percentage but at 1 MHz ( or 1000 KHz) its quite a bit!  The D layer that does a lot of the absorbing at  MW frequencies is already starting to form,  and the frequencies at the bottom or even middle of the band are affected much more than those at the top.
       In my drive to work in the morning,  this is really apparent as the Chicago stations on 670,720,780 and 890 though all broadcasting non directionally with the same power are often of very different strengths.  The lower stations may be very weak as the sun is just rising, while 890 will be stronger.  Sometimes the lower ones are inaudible or even covered by other stations from Mexico that are in the same time zone or to the west of me.
       Stations from Mexico City provide another such "barometer".  Usually stations on 730, 900, 940,1000. 1030,1060 and 1220 from Mexico City are audible here. They are a bit to the East as well as being South of here.  Oftentimes the stations on 1000,1060 and 1220 are much stronger than 730 and 900 even though they actually run less power.  This situation is the reverse when the path is well in darkness.
       Other stations from Mexico show similar characteristics, though the comparison is not really as good because they are from different locations and are different distances. The 1050 ( XEG) from Monterrey will be much stronger than the 540 from San Luis Potosi. The 990 will be stronger than the 540 or 730. The 800 from Juarez ( XEROK) will be much stronger mainly because it is from the West of me by several hundred miles ( I am in Waco, Texas) while the 1570 ( XERF) is always the strongest of all, even an hour after sunrise while in the same time zone.  Of course, its is also the closest being just across the border from Del Rio.
       At sunrise, conditions seem to change very rapidly.  A station that is fairly well audible low on the dial when I leave the house at 1140 GMT might be taking heavy QRM hits or be fading down by the time I get to work at 1200 GMT. Stations high on the dial will still be fairly strong.
       Another thing I have noticed this time of the morning.  As the sun begins to creep over the horizon, skip on relatively nearby stations gets shorter. Stations like KMOX from St Louis-1120- will come up in strength,sometimes covering a new daytime station in the Austin area that has just signed on for the day. KWKH in Shreveport, Louisiana--1130--will come up above the Mexican station that sometimes dominates the frequency. KCTA in Corpus Christi on 1030 will come up over Mexico City's XEOY.
       Just as a note, KCTA is an interesting DX target. They are a Christian station that is day time non directional on 1030 KHz. However, because their dominant station, or the station they must protect, is WBZ in Boston, well to the east,  they get to sign on an hour before sunrise Central Time.  They also have a presunrise authority of around 250 watts.  A DX-er to the  West might have a good chance of logging them just before sunrise Texas time if he could null Mexico City.
       In addition to the changes as time passes through sunrise, there are also significant changes day to day due to other conditions.  In years past,  I had sort of assumed that prop in the Medium Wave band was pretty much stable day to day. This thought may have been somewhat reinforced by dealing with construction of stations and being aware of requirements for protection of other stations from interference at night.
       However, over the years I have noticed that such is not the case.  There can be considerable variance in signal strength from night to night, and particularly during the " grey "hours of dusk and dawn.
       It is one thing that I have enjoyed observing as I drive to work each day and even after over fifty years of DX-ing continue to learn.  At the same time on consecutive mornings,  the same station might have considerable different signals, particularly at the low end of the dial. For example, WIBW on 580 from Topeka, Kansas is a regular here just before sunrise.  Some mornings it comes in almost like a local station.  Yesterday, however,  it was almost covered by a Spanish speaking station. ( probably Piedras Negras) Once XEMU goes to daytime power, Topeka is gone. But with the border station on night power, WIBW usually makes it pretty well, though there can be exceptions.
       I have a couple of good barometers for enhanced prop.  Two stations from the Dallas area have relatively low power at night but have directional antenna systems that still deliver fair signals to the South and into Waco, KSKY on 660 and KAAM on 770.  A quick punch to those frequencies as I start the truck up in the morning ( I have preset buttons for them just for this purpose) will give a good indicator if something is up. If they are in with fairly clear signals,  I check the higher part of the band for DX.  However,  if they are being covered or have signals significantly causing them to "hop",  I know there is a chance of hearing something good down low in the band and I can spend the few minutes of driving DX hunting on that part of the dial.
       Other good "barometers" are 880 which is usually KVRN from Nebraska with some Mexican QRM and 980 which is usually Kansas City.
       The thing to note is that even the medium waves are not the same every day. Things can often change radically from day to day,  particularly if there is some kind of major solar activity.  Its worth checking your own "barometer" stations daily to get a clue if it worth checking for possible new logs.
       An example is the past couple of days ( October 9-11) when there was solar activity that totally mangled the upper HF bands but led to enhancement of MW and LW bands. here in Waco, Texas, a semi-local station ( WTAW 1620 in College Station, Texas 90 miles away) is usually audible day and night, though with some co-channel interference heard at night, usually from radio Rebelde in Cuba.  This past Friday night, Rebelde was propping in so strong it completely covered WTAW.  You could not even tell it was there! That led to tuning the rest of the band and logging a half dozen new stations.
       And finally,  I apologize for a lack of posts the past few weeks.  We have been making repairs to our home following a water pipe break that flooded part of the house, requiring a replacement of a wall and removing and replacing the flooring in the room where the radios and computer are located. Luckily none of the electronic equipment was damaged, but all had to be moved out and stored during the repairs.  Happily all is ( almost) back to normal now and hopefully at least weekly updates will be available from here out.  You are invited to scroll back through the archives.  Many articles are not time sensitive and hopefully will provide some entertainment if not useful information about a life behind the lighted dials!  Good DX.