Developing DX-er's Ears

The last three weeks has seen a relative low amount of time behind the radios. Thunderstorms, rain, and flooding have hit Texas and in addition to everything else, the QRN ( static) has been horrendous. That has not to say there has been no DX logged, there has, but it has been at a cost in time, concentration and pounding of the ears to pull it out.

When the lightning has not been so close as to be dangerous to have the antenna connected, the upper bands have been listenable during the day, at least on frequencies above 15 mhz Early in the mornings Europeans and Russians would make it through on 15 and 20 meters, though 20 was often plagued with heavy static. In the late afternoons the regular flood of Japanese stations would be in with fairly good signals, though sometimes even on 15 meters masked by the static crashes. A couple of good catches were logged, including a South Korea on 15 and Kenya (5Z0L ) and Palau ( T88HR) on 17, though it took some good picking to pull out the callsigns This was on 24 May and all on cw. A group on Bear Island Svalbard-JW9JKA- was also heard on 15 meter sideband but it took almost fifteen minutes to identify.

The lower bands were all but useless for DX on phone. DX of broadcast stations on 120, 90, and 60 meters was a total washout and even weaker stations on 49 and 31 meters were tough to pull out.

This past weekend ( May 30 and 31) saw sunshine return to Central Texas, but on the low bands the static was still horrendous because there were still heavy storms in areas within the first skip zone on the low bands, and yes, static crashes are propagated just like desirable radio signals.

The WPX contest would normally have provided a treasure trove of signals, but for me, the event of a grandbaby's birthday precluded a lot of time in front of the radios ( there ARE priorities when there is a three-year-old involved!!) But even the available time on the low bands was still pretty tough. In the evenings, on 40 meters, only the strongest of Europeans were coming in Friday night Texas Time. Only the big club stations in Italy and Croatia were identifiable. Saturday night was a little better but once again only the powerhouses were pulled out. I did log about 35 DX stations through the crashes, notably stations from Poland, Cape Verde, Serbia, Germany, Slovenia, England, Bulgaria and Spain. All had to be in the S-7 to S-9 range to be readable through the noise.

There are ways of hearing things even in these harsh conditions. I have long been a believer that in hunting for weak DX or trying to identify a station in a jumble that the best filter “ is the one between the ears”. There is no physical or software filter in the world that can give totally QRM or QRN free listening. Mechanical or electronic filters can do nothing about two signals that are superimposed or can be so narrow as to strip the intelligence from an AM or Single Sideband signal. And when it comes to static, well that is a whole 'nother story!

The battle to fight static crashes has been going on ever since the days of the coherer detector. While not always continuous, the loud bursts can either totally cover the desired signal or in periods be so much stronger than the desired one that the receiver sensitivity is either pushed down as the Automatic Gain Control operates or that the overall loudness of the static forces the operator to reduce the gain to protect his ears.

In years past, this problem was solved in a simple way. The AGC in the receiver would be turned off and a hard diode clipper in an audio stage would be used to brute force chop off the higher noise peaks.

In some circuits, the level of clipping was adjustable, but in most it was not. There was a switch on the receiver panel marked “NL”, “ANL” or “ Noise Limiter” or just “ Limiter”. Many times if weak signals were involved, the “ bite” of the clipping circuit would not be deep enough and there would still be a considerable difference between the strength of the desired signal being listened for between the crashes and the crashes themselves. With the AGC off to prevent the receiver sensitivity from being driven down by the static and the higher peaks getting past the clipper, most often the “ Clipping” took place within the ears of the DX-er. I am sure that this resulted in more than one case of severely damaged hearing for a couple of generations of hams and listeners! It should be noted that the only way to listen under these conditions is with headphones. Trying to hear and copy through heavy trash with a loudspeaker is a total study in frustration. And if there are other family members in the house within earshot, such can be guaranteed to result in a pillow or something more deadly being thrown your way!

Newer noise blankers were developed in the early sixties that made use of sampling noise pulses usually outside the passband to which the operator is listening. These pulses would then be used to generate short duration signals to turn down the gain of the receiver for just the brief instant of the noise pulse. These can be seen to work by watching the s meter. These work pretty well on short duration pulse noise generated by spark plugs or other electrical “transmitters”. On some receivers, however, they generate some interesting artifacts. If there is a particularly strong signal in the passband that is being sampled and which is not actually heard where the operator is listening, that signal will cover the offending pulses, meaning the receiver won't work to get rid of them and the operator will hear annoying bursts of noise over the desired signal that duplicates the signal he is not hearing. If there is a jumble of strong signals, as during a DX contest, this results in a ragged up and down bunch of noise on the desired signal that is almost more annoying than the background noise that would be there without the noise blanker operating! I have been known to just turn the thing off when that happens.

Other noise limiters or blankers can have other effects;. Some can greatly distort stronger signals, especially phone signals. There are some radios that have adjustable noise limiters, with a control that adjusts how deep the device “ bites” into the signal to allow the operator to set up the best compromise between distortion and noise reduction.

Few of these devices really do much to help with the thundering crashes that accompany spring storms! Sometimes it gets back to the very basic idea of concentration. This means the operator must narrow his mental focus on just what it is he wants to hear. The same kind of effort is often used at a loud, crowded party where there is loud music and dozens of people talking and there is someone with whom you are trying to have a conversation. You simply concentrate on that one person's voice and mentally tune out the noise around you.

This same technique is used in DX-ing. You focus on the one pitch tone of the cw signal or the one voice in the jumble and attempt to mentally separate it from the crowd or from the background noise. It is not easy at first. All those other sounds are distracting, but you must learn to simply ignore them. The development of this ability is really the difference between a good DX-er and someone who just sits in front of the radio waiting for the DX to jump out the speaker. The development of this technique is a good explanation of why a seasoned Dx-er who started out with rudimentary, simple equipment consistently logs more DX than the new arrival in the game whose first receiver is an expensive, filter laden box who depends on those filters to separate the good stuff from the chaff. Sometimes those folks never develop the ability to mentally filter out the trash and sometimes get disgusted with the hobby and drop it because they can't understand why they have bought all the necessary stuff and can't get the good DX into their logs. Sometimes they even get to wondering if the hobby is all its cracked up to be or if the old hands are just making it all up!

Is there a way to tell you how to do this? As I write this, I am mentally scratching my head trying to come up with the words. All that seems to come out is “ concentration”. Pick out one voice and latch on to it, just as you would to one tone in a jumble of cw signals. Mentally listen through the noise and jumble of other signals. Sometimes with AM signals, if they are on exactly the same frequency without loud heterodynes this can be done with practice. With cw, for me it seems to be easier if the desired signal is at a low pitch. If copied at 1000 hz or so and a signal is 200 hz away, there is not much difference in pitch. But if copied at 300 hz, and the interfering signal is 200 hz away, it “ sounds” almost an octave away and is more easily mentally separated. If the interfering signal is much stronger than the desired, this becomes more difficult, especially if it “pumps” the AGC down. Selecting a faster AGC recovery time or, if possible, turning off the AGC altogether may help prevent the receiver from driving the desired signal down in level. If QRN or other man made pulse or broadband noise is not a problem, you may find that turning the noise limiter off will help separate voice signals on the same frequency because the Intermodulation Distortion that would tend to cause the audio signals to seem to blur together may decrease.

By the way, this brings up a point I have heard when people talk about different receivers. Some BCB DX-ers will say that the effect of mentally separating voices or signals in one jumble is easier in some receivers than in others, that some receivers tend to blur them together, while in others, signals though mixed, seem to be more “ separate”. My theory is that the Intermodulation Distortion either in the audio or perhaps even in the Intermediate Frequency stages might be better in some receivers than in others...that the linearity of the amplifiers might be better. That would make sense when some folks talk about how some of the older, high end tube radios seem to “ sound better” or clearer than some of the newer, perhaps budget solid state radios. The old tube amplifier stages, particularly in the older radios tended to be designed with more “ head room” to handle strong signals. To my ears at least, this was the case with the Hammurland and National receivers. But then, that just might be personal preference or what I got used to. I do know from working with broadcast audio for many years that Intermodulation Distortion can make music sound muddy even if frequency response tests with individual tones in an amplifier will show very good frequency response to very high frequencies, while an amplifier with low IM and even less high end response will still tend to deliver music that just sounds “ clearer”.

Back to the issue of filters for a moment. Software filters, crystal filters, and mechanical filters can be very narrow but cannot tell which signal you really want. They can be narrowed down once you pick out the one you want, but you must first determine which one in the pile you want and if you start with the window too narrow, you can't do that. And how can the DSP tell difference between a heterodyne you want to get rid of and a cw signal you want that might be beating against a carrier nearby? Those decisions are best left up to the person twirling the dials! And perhaps the real fine tuning is to be done with that “ filter between the ears”! Good luck in developing your DX-ers ears and fill that log up!

Stormy Weather

I have always been one to be concerned about lightning damage to my solid state gear. In the old days of tube gear, other than a direct lightning strike, I never thought about it too much. Oh, if a thunderstorm was coming, I would disconnect the antennas, often leaving the connector lying behind the radios or sometimes on the window sill before I had the leads dropped down through the wall.

Even then I knew about inducing of high voltages in long wire antennas by nearby lightning activity. It was brought home to me one night during a storm when I kept hearing a frequent “ Snap! Snap! Snap “ sound. It actually woke me out of a deep sleep. It took a few minutes to figure out what it was. The antenna lead I had disconnected from the radio and left lying on the window sill was arcing over to the aluminum window frame which was grounded! The arcs were well over an inch long. It scared me a bit and I got up, opened the window and tossed the lead outside!

The next morning, I got to thinking about what had happened. The antenna I had at that time was about seventy feet long and suspended between two wooden masts that were twenty feet high. After reading a bit and talking with some of the older hams at the local radio club, I figured out that nearby lightning activity was inducing currents into the antenna, just as passing radio waves did. The “ signals” from the lightning were just a whole lot stronger, and certainly well over the several microvolts the radio signals might have brought.

The tube receivers were physically pretty stout in those days. Voltage spikes don't scare 12SK7's or 6BZ6's much. After seeing the arcs, I did get concerned about the small Litz wire that the antenna coupling coils were wound with and thus began my protective attitude toward the radios. I still did not disconnect the antennas every day, only when I suspected a storm was coming. And I still used the radios during stormy weather if the cell with its attendant wild lightning was not directly overhead.

When I got my first really long antennas up, that changed a bit. At one point I had a long horizontal “T” up that was supported by a salvaged utility pole and that spanned our entire back yard and two neighboring lots, running along the rear of the neighbors garden and home and all the way to a street that connected to the road in front of our house. There was probably almost 300 feet of wire up. Now that thing really did collect the voltage! In fact it was not just during thunderstorms, but I heard the arcing behind the receiver once during a blowing dust storm. Static electricity was building up on the wire and finally arcing over.

There was no damage to the radio, but the fact that there was arcing inside the house led my parents ( I was 13 at the time) to tell me to “ do something about that”. The answer was a big knife switch outside the house that would allow easy grounding of the wire during scary or threatening times. In fact, it became a habit to ground the thing any time not in use. A shorter longwire or simple dipoles or verticals were used during rough weather. Of course, when lightning was in the immediate area, all activity ceased.

When I began working at my first radio station job, I learned more about lightning protection. The four broadcast towers at my first radio station frequently arced over during storms, with the transmitter tripping off momentarily, then automatically resetting after the arc stopped. There were two large metal balls near the base of the tower only about an inch apart just for the purpose of sending the current from a near or direct strike to ground. One was connected to the ground system, the other to the tower and they were spaced just far enough apart for the RF not to arc across them during normal operation. During storms it was common to see and hear arcs across the spark balls. There were also static drain chokes across the inputs of the antenna tuning units at the base of the towers ( if you ever wondered what was in those little “dog houses” at the bases of broadcast towers, that's it...they contain matching networks-usually T-networks—to match the impedance of the towers to the impedance of the transmission line and in some cases to provide part of the phase shift for the directional system)

All of this gave me ideas on how to protect my gear at home. Some amateur handbooks also called for putting neon bulbs across antenna inputs of receivers. They would normally be open, but if the voltage on the antenna ever got higher than the break over or firing voltage of the neon bulbs, they would ignite and conduct the charge to ground. There were also RF chokes to put across the receiver inputs or 100 megohm resisters to drain the static charges.

The best overall protection, however was to disconnect the antennas and thus not use the radio at time of highest danger.

With the advent of solid state receivers, the problem became more acute. The junctions in the early transistors and connections in the newer forms of transistors and other chips just won't handle the higher voltages that can appear on antennas at times. The newer rigs have some protection built in, usually in the form of high resistances across the input, chokes and diodes...but despite all that, these rigs are more vulnerable than the old tube gear. I lost the front end of my venerable old FT-101 during a storm during which I was operating a contest. I had watched the weather, had the radar on a local weather channel up on the tv and watching and figured that the core of the storm was far enough away. However, an errant lightning strike in my neighborhood took out the front end of the FT-101 even though my antenna was not hit.

That incident got me a little paranoid about using gear even to listen when the weather got questionable.

Which brings me to this past weekend. It was time for a cluster of small contests...including the UN ( Kazakh) contest and the Baltic States contest and I really wanted to get in there and see what there was to see. I am sure the newer gear is more protected than the older solid state stuff, but I was still nervous. I told myself that when the static crashes got strong on the lower bands or became audible on the higher bands, I could just shut down. That lasted about thirty minutes, because it began to look like it would be dicey the entire weekend.

Then came the answer. I wouldn't use the new gear. I would unlimber some of my old favorites that I knew would be “safe” ( or at least “safer”). Thus brought the old Drake 2 B into play along with my venerable old Hammurland HQ-170. The Drake doesn't use narrow filters in two IF's like the newer Icom, but it does have a very good Q multiplier that operates in the 50 kHz IF. The Hammurland also is triple conversion with a 60 kHz IF. While they don't have the digital readout, why is that really necessary when DX-ing the ham bands as long as you have crystal calibrators to tell you where the band edges are.

Did it hurt using the older gear? Well there is the continuous hiss and ringing sound when using the Q-multiplier on the Drake and the hollow “ wind blowing across the end of a pipe” sound of the Hammurland in the narrow selectivity mode...but the results were good. The DX was probably just as good, or nearly as good, while the operating convenience was not as good. After a few minutes the feel of using the Drake came right back...and it was particularly comfortable using a receiver that has been in the shack almost fifty years. The Hammurland has been with me since 1976 and the trick of swapping sides of zero beat with the BFO to get rid of pesky QRM came back quickly.

Did I miss anything? Perhaps. But I do know I what I did NOT miss using those old friends. There was still the long strings of JA's the first evening on 15 meters and the first morning on 40. There was still a long list of UN-prefixed stations on 40, 20, and 15 ( the band was just not cooperative on 10...or was it the receivers? I could not tell...maybe some of you could tell me in the “comments”.) There were several stations from South Korea in the log ( DS and HL). There were 4X and 4Z stations from Israel. There was SV5/DL3DRN from the Dodecanese. And there was

3B9, VP8, SV2, YB8, several ZL and VK stations, several UA's and R's from various locations, UX's and UR's, TA, S5's, and later in the weekend during non contest hours OJ0 ( Market reef) TF3,5Z0L, T88,A45 and JW9. Not too shabby for fifty-plus year old radios. And the solid state, new, high tech stuff got to live to fight another day and I did not have to miss logging the goodies because of nearby storms.

Now none of this is to say that I took chances or advocate taking chances with bad weather. At the first sign of really nearby lightning or the sound of thunder less than a few seconds behind flashes seen in he window, the plug was pulled and the feedline thrown out the window. I want to make sure I get to live to tune another day!!

A Magic Time on the Radio

This last Friday night –May 15, 2015 Texas time—was one of those truly magical times in front of the radio. It was one of those days like I had imagined shortwave listening to be when I was a kid, times when it seemed all bands were open to the entire world all at one time.

The impression probably came from reading the short wave listening columns and articles in the magazines. I just did not realize at the time that those columns and articles often contained an entire month's worth of “ best of “ listening reports from the contributors to the columns. I did not thik that all those reports were just funneled down into one or two pages of the Popular Electronics or Electronics Illustrated that I was reading in the late 1950's and early 1960's.

Every once in awhile, everything will line up just right to make that imagined scenario a reality. This past Friday night was one of those- a veritable “perfect storm” of conditions.

The previous ten days or so had been pretty poor for listening here. There had been terrible thunderstorms almost daily. One nearby area got ten inches of rain in one afternoon leading to flooding. We did not have that much at my QTH, but there was enough to have everything a bright green. However, the lightning had been so intense as to lead to not only unplugging the radios and disconnecting the antennas, but to also throwing the feedline out the window!

Friday was a little different. We got about six-tenths of an inch of rain Friday morning, but the sun peeked out Friday afternoon. After dinner, I decided to dare checking the bands. I reeled the RG8X back into the shack, shook the water out of the PL-259 and decided to start the evening listening on the FT-757GX. It was just before 9 PM my local time, or 0200 Saturday morning May 16 GMT. I plugged the headphones in and slowly, gingerly brought the AF gain up. I was being careful because earlier in the week the static crashes had been so bad that with the headphones on, each crash would be like a well delivered hammer blow to the temple.

But this was different. No only were there no audible crashes on 20 meters, the sometimes irking power line leakage noise was totally absent. Other atmospheric noise was almost non existant. Was the antenna really connected? Yes it was! The band was just that quiet.

The FT-757-GX had been tuned to 20 meter phone when last used and came up on 14205 in the upper sideband mode. After a moment of relative quiet, the sounds of a nearby pileup became audible. A light touch of the dial found it centered on 14204. A Canadian station was clearing with the guy he had snagged in the pileup and the DX station came back on stronger than the Canadian. There he was...well above the noise with that floating, airy sound DX stations sometimes have...and identified himself as A92HK in Bahrain!! The S-meter showed about S-5, but the band was so quiet that he really sounded strong.

Listening over the next quarter hour was amazing. I could hear all the stations calling him. On that one frequency were US stations, stations from all over Europe, most areas of Russia and Asiatic Russia and South America all audible at once. Some of the Europeans were over S-9. The Asiatic Russians had that characteristic fast QSB, almost fluttery and echoey sound. The US stations were weakest of the bunch. It was as if almost the entire world was being funneled into my little radio in Waco, Texas!

After about a quarter hour of amazing listening, I finally brought myself to tune up the band a little bit and found another pileup on 14214. At the bottom of this one was 9K2UU in Kuwait, also with a good signal and also with stations from all over the world calling. And on up at 14270 was 4Z5PJ from Israel. All of these stations and their respective pileups were heard in a twenty minute period from 0200-0220 GMT.

With all this going on, why change bands and look elsewhere? I don't know. It might be like the question in an old joke: “ Why did the chicken cross the road?” I made a quick foray to fifteen meters, and started at bottom of the cw band as is my usual method. The band was also quiet, but obviously not dead. I don't know how scientific it is, but I can sort of tell if a band is open even if no signals are present. Its something about what the background noise sounds like. Not the static or line noise, but the overall atmospheric noise that is probably made up of an aggregation of local noises that somehow get propagated.

Anyway, the band sounded like it was worth more than just a quick check, so I spent some time slowly tuning across the cw portion. I usually do this with the bandwidth wide open, tightening it down if I run across a cluster of stations that need separating. There was a weak station on 21025 signing off with someone, then signing his call. I missed it but stayed there. Experience has taught that if a DX station clears with someone and no one calls immediately, he will often call CQ after awhile. Its not good to quickly tune away just because the QSO ends. A little patience pays off.

Such was the case here, because about a minute later he was back calling CQ. DS5DNO from South Korea. Not extremely rare, but not every day either. A good one for the log. I heard him work a few, then moved on, this time to 17 meters.

This was where the gem of the evening was found. It wasn't that it was rare DX for me, but because it was hearing a really good QSO for someone else. I found HA9FTA on cw on 18073.5 working a small pileup. HA from Hungary is not that rare at all here in the States, but he had attracted attention because of his signal strength: a very solid, steady S-9 peaking at 10 DB over S-9 frequently. Once again he was working lots of stuff from all over. While many of his contacts were US stations, I could hear many Europeans calling him.

The fun came when I heard one station low in the pile calling him. ZL4AS. Now New Zealand is a long haul from HA. Given where the sun line was at the time, I am not sure which way the signal was going from New Zealand to Hungary, but either way was a LONG way. The first couple times he called, I am sure the HA could not hear him through the deep pileup. But then something interesting happened. Many other US stations must have heard him and STOPPED CALLING! It was like a parting of the waters to let him through! Now that is radio sportsmanship. One more call, and the contact was made.

Its not often that one gets to hear both sides of a great DX QSO but this was one of them....and with good sportsmanship thrown in for good measure.

Of course as soon as the US stations heard that the stations were safely in each other's respective logs, the pileup resumed with great enthusiasm. But it was a great moment to hear!

A quick run up to the phone band found another gem, again not super rare but certainly not to be passed up. SV5CVY from Crete was in at over S-8 completely in the clear. This while just down the band, a ZL had been coming in well from the opposite side of the world!

Back to 17 meter CW led to RA9YN, UA9FGO and RG0A all from Asiatic Russia coming in well with flutter and echo. All of this in just over a half hour of listening. It was as if DX Kharma was making up for the lousy listening earlier in the week.

A quick run back to 20 meters turned up strong signals from an LZ ( Bulgaria), F6( France), RA6( Central Russia) and a particularly good signal from LY2J in Lithuania. All were S-7 to S-8 with the LY2 at 10 db over S-9. Interestingly a VE2 ( Quebec province, Canada) was only S-3. But that could have been either prop or because of a highly directional antenna pointed at Europe.

Well lets check some of the lower bands and see what is happening there. Whoa...down on 30 meters, there were still some static crashes heard peaking at S-9. Maybe not local, but perhaps they were propping in from somewhere else. They skip just like anything else! ( I can remember times in the past when car ignition systems were much noisier hearing spark plug noise propping in on ten meters into East Africa!!) One good DX station was heard above the noise: OK1AMA from Czech Republic on 10111.3 though it took some repeat listening to get his call sign pulled out through the noise.

Eyelids were getting heavy about this time after a full day of work and getting up about 4 AM that morning...but still time to check 40 meters. From the static on 30, I figured the noise on 40 would be worse and it was. But the signals were quite strong. The first QSO I ran across was on 7012.1 with the station signing being K3STX, very strong above the crashes. But then the station he was working was strong too. Turns out to be a station heard and worked here many times: F5IN with an S-9 plus signal into Texas from France on 40 meters. Up the band a ways I find a pileup about 7015 and figuring the target may be listening up from his frequency, I check down one and find TA3D from Turkey coming in on 7014..also S-9. What are those guys running??!! They are always strong here!!

By now the sleepies are catching up with me. Perhaps in the morning this trend will continue, but for now its time for an emergency nap ( or more) after a long day.

As I shut down the FT-757-GX, turn off the Astron power supply and disconnect the antenna ( I never leave an antenna connected on any of my radios when not in use!) it strikes me that all this adventure took place in just about an hour. Its 0253 GMT. Good stuff in the log. Almost thirty log entries and among them some really good stuff coming in from all over the world at the same time. Truly a magic night...one that lived up to all the daydreams while reading the magazines in 1958!

Listening in on the “M” Contest

This is kind of an example of a “ day project” in the shack here. The idea is to spend some time trolling through the ham bands during a particular contest, looking for participants from a particular country, or sometimes just finding what there is to find. The “M” contest involves mostly Russian stations trying to work each other and DX with others trying to work them.

This was not to be a full time effort as in the case of my SWL versions of other ham contests, but of some time spent through the day an hour or so at a time. Its not a matter of needing the countries or anything, though in this case I did pick up Kazahkstan on a new band, but of seeing what there is to hear and enjoying the thrill of the hunt.

The tools for this one were an Icom R-75 with dual 250 Hz filters ( one each in 9 mhz and 455 khz IF's) and an 80 meter top fed sloper facing east and up 45 feet.

Start time was Saturday morning, May 9, 2015, after making coffee and feeding the managerie, i.e. four dogs, three cats iside and filling the outside bird feeders, plus checking the front porch to see if either of two stray cats who come by for breakfast had shown up.

Sitting at the operating desk, full coffee cup in hand and slipping on my aircraft style headphones, I made a preliminary run through the WWV frequencies to get a feel for the prop. Thunderstorms elsewhere in the state made themselves well known on the lower frequencies, though 2500 and 5000 kHz WWV's were in strong, with WWVH slightly audible in the background. The 10000 khz frequency was marked by lots of QSB and WWVH being stronger than WWV. The 15000 khz frequency was really up and down, not strong at all with WWVH also almost as strong as WWV. For reference, the location here is Waco, Texas.

First stop was 20 meters, getting there about 1225 GMT. Things were not really very promising at all...there were not many signals to be heard and they were all really down in the grass. The only stateside call heard was KW4JA, and it was fluttery sounding, wildly varying in signal strength and marked with mild echo. He was calling CQ with no takers.

A sweep through the rest of the band turned up UW2M from Ukraine on 14023.1 just barely over the noise. Usually potent HG7T was on 14012.7 coming in about S-5, RJ4P on 14020.3 also at the noise level and R9FT about the same on 14027 and finally Belarus in the form of EU6AF. They appeared to be making contacts within Europe, but working few North Americans. They were the only ones heard on the band.

The move was made to 15 meters. This may sound strange, going to the higher band when the lower one was poor, but I have learned that strangely enough, sometimes 15 opens well to Europe more strongly earlier than does 20 meters at time. The sun has been up there much longer—it is midday, and the band will be open solidly there. Why this occurs is a little puzzling to me, but I have learned it often happens, so who is to question, just use the knowledge.

I got there at 1234 GMT, having spent only about ten minutes on 20 meters. I usually start at the bottom of a band and sweep upward. Signals were not strong, but there were more of them and the noise was lower on fifteen than it had been on twenty.

The first station identified was RV3AMU about S-3, just flirting with the noise level. However, the station he was working was considerably stronger: NP2X in the American Virgin Islands peaking about S-8. Right after that VE1DT called the NP2 at about S-7.

Tuning just a bit up turned up RC3W about S-5 only 400 Hz up. At 21007 I heard the familiar sound of K1ZZ holding forth well over S-9 and working a string of folks. For SWL's listening in the hambands for DX, a good tactic sometimes is to find a station “nearby” working a string and stay with him. Often the prop to you will be similar as the prop to him and you may hear a good string of DX stations working him. Sometimes the “nearby” station may be weak or maybe even inaudible, but it will bring a good run of good stuff into your log! In this case, I was able to hear him work S53F in Slovenia and EA1VT in Spain before his run broke.

Going up the band I noticed conditions were gradually improving, with signals going from just above the noise level to being comfortably copyable. UT1IM in Ukraine was working a string on 21010 and as I listened to him for about ten minutes beginning at 1244 GMT, he went from S-4 and marginal copy with fading to a solid S-7 in just that short time. Things were looking up!

Going up the band, I was somewhat surprised to hear the first of several Asiatic Russian stations, though with echos and flutters. The usual early morning fifteen meter openings don't usually turn up stations that far over from here. The first in the log was RU9WZ on 21011.7 at 1246 GMT. He was followed by OE8Q and UA6CC a minute later on 21012. With the narrow filters in the R-75 or in my old 75S3 in years past it was not unusual to log three stations within a 1 khz span during active contests. ( I wish I still had the old Collins!!!!)

Over the next half hour, DX stations were logged at a rate of one or two per minute. In rapid succession, RT9A, UA4W, R9DX, then a surprise 4L8A from Georgia on 21023. One of only a few Scandinavians of the morning came in with SK2T next, though it took some intensive listening to pull the call out with its deep fading, echo and flirting with the noise level on 21023.

A mere touch of the dial up brought in RC3W, SN7Q, R8TA,LZ2A, G3NYY and RC4SAA in just a couple of minutes!

A short break for coffee and an unusual callsign jumped into the log: RP70TM. This was a casual contest participation, so when breakfast called there was a short break, then a return at 1447 GMT

This started a quick run that included some stateside stations starting to show up with very strong signals as the day got lighter and lighter. In the log were another Ukraine station in the form of UX1HW, US station W0YWW at S-9+10 db, I6NO, K0DEQ, OE1PEW in Austria, DL8MLN in Germany, VA3DX in Canada, NN4K then N9BX at S-9+20 db.

Signal strengths from Europe were steadily climbing, with almost all signals S-7 and above by 1500 GMT. At 1501 there was a real surprise in the form of JW8DW from Svalbard on 21010 at S-7 with some flutter. While a good one, this was not a new one for me on this band ( new ones get harder and harder to come by the longer you play this game!) The next good string included R9AE, R7AW,WJ9B, VE1DT, RF9C, UT1IM again still going strong, UN8GD in Kazahkstan giving me that new one on 15 meters, RJ9A, HG5T at over S-9, OK1DOR. Through the rest of the day, coming and going from the radio, three log pages were filled, mostly with European Russian stations...well over a hundred for the day.

Its somewhat strange looking at the log and marveling at what I would have thought of logging these stations in my beginning days of DX-ing. It was not even imaginable. Why these things were not heard in those days is an open question, Certainly some of it was a lower skill in copying CW. Some was probably lower sensitivity of receivers, thought the NC-88 should not have been that bad. Maybe it was the poor selectivity ( probably 10 khz wide with no filters ) Some was not knowing when to listen. A lot was probably antenna, having a mostly horizontal antenna at a height that was not conducive to good low angle response.

This is more DX in a few hours than I logged in my first two years of listening. Hearing Russian amateurs in my early days was an extremely rare occurrence.

So does this mean I am getting jaded and losing interest at hearing this many good DX stations? No! For some reason, it never gets old. Even logging JA's is still new every time. If it ever does seem to be getting dull, I just turn the radio off and come back later. The magic of those signals leaping into space, bouncing off the ionospheric mirror and diving down to make little currents flow in my antenna as they zip by never seems to get old. As I get older, it seems the exotic sound of those weak, fluttery signals sitting on the antennas like butterflies on your arm is probably what keeps me young!

Learning to Dig Deeper for DX

The body of this post was written a few months ago as part of a planned longer biographical look at DX-ing.  It refers to the early days when I first became aware of reference materials for helping to identify DX and the first steps beyond casual, random tuning of the bands and just listening to what I found.

In those days I was still using my very first receiver, a semi-homebrew thing consisting of  a six-tube broadcast receiver with one RF and one IF stage with a single tube converter in front of it to tune roughly 6-18 mhz. It had been part of a series of kits that came with a radio-tv repair correspondence course my dad was taking in the early fifties. In about 1959,  I was entrusted with it, finished the receiver construction and built the HF converter.

The receiver had no real frequency calibration...just a 0-100 logging scale.  The selectivity was very broad and on the shortwave bands, the image rejection was all but nil. That brings us to this episode. This refers to an era in the late fifties and early 1960's.

After the first few months of listening and after getting my first copy of the World radio TV Handbook, I started listening beyond the “easy” targets. I began spending some time trying to identify some of the weaker signals and some of those in different languages.

The way the Voice of America ID'ed in those days actually helped. They would identify the transmitter site and language about the be transmitted. For example : “ This is Voice of America transmitter KNBH in Dixon, California. The following program is in Thai.”( or Russian, or Polish, or Swahili...) It was not long until I was able to identify languages by their basic sounds, even if I could not understand what was being said.

The WRTH ( World Radio TV Handbook) helped in another way. They included phonetic spellings of station identifications in the various languages.( “transmite Radio Atlantco”,”Ici Bamako”, etc). Sometimes the station identity could be confirmed by what band, what time and what language was being transmitted, sometimes with other clues such as locations or city names being repeated a lot.

There were also the Interval Signals. In the days of analog dials and stations seeking listeners they knew often had simple receivers, the stations would help listeners find the stations before programs started by transmitting these signals. Often they were a phrase of a tune, or a short musical excerpt repeated over and over again. The Voice of America used “ Columbia, the Gem of the Ocean” and “Yankee Doodle”. Radio Moscow used a short phrase played on chimes. The BBC World Service used three tones played over and over. Radio Australia used a music box version of “Waltzing Matilda”. The WRTH and many of the DX articles in the magazines of the time would list these Interval Signals. The WRTH went one step further in publishing the actual musical notes under the listings for the stations with the name of the musical piece from which it was taken.

Between these clues and a development of the ability to listen intently through noise and interference, the percentage of stations being identified began to improve. The big thrills came with the logging of the first African stations. My first were the Voice of America Relay in Monrovia, Liberia. In those days each transmitter site identified itself before the programming began " This is the Voice of America Relay Station in Morovia. the following program is in Arabic".  But there was something particularly exotic about hearing the VOA relay from Tangier. Then there was the second station in the log: ELWA, a missionary station that was really weak here. I finally realized that it was probably beaming away from us and toward the center of the continent. It was a true disappointment years later when both of these sites were destroyed in the war that swept that West African nation.

During that same period Radio Brazzaville from the Congo had strong signals here, as did the South African Broadcasting Corp. For many of these, it was a matter of learning what the best times for receiving the signals would be. It was also about this time that I found the VOA station from Rhodes, which was not a land based station, but broadcast from the vessel “ Courier”. The QSL card depicted a blimp like balloon holding an antenna aloft. I never knew if that wire was the one that the short wave transmitters used or if it was just for the medium wave outlet the ship also carried.

I had not logged any Asian stations at all by this time, but again it was a matter of learning when to listen. I think I shocked my parents when I began getting up early and no longer had to be drug out of bed to get ready for school. It was on one of those early morning forays where I first heard NHK from Tokyo on 25 meters. I don't know why I had so much trouble finding them the first time, unless it was just some quirk in the directional pattern of my antennas. I know I never heard any Japanese hams on that particular wire after I got my ham license, either.

It was during one of those morning sweeps that I found one of my long time friends on the dial for the first time: Radio Australia. The first time I heard it was on 9580 and it became a morning fixture to listen to while dressing for school. It seems that 9580 was the morning spot for that station for many, many years...in fact until just a few years ago. I was really surprised to find when I got a QSL from them that some of the hours that I would hear it were not the actual North American service, but the Pacific Service and the power for the time I sent the report in was just 10 kw! Though I spent many mornings hunting, I did not hear their band mate, radio New Zealand, at all during that period. I remember wondering if it was because of their power. In those days, the WRTH had them listed as having just two transmitters with 7.5 kw each. To this day I am not sure if I just missed them or if perhaps their antennas were beaming a path not favorable to the US.

The 31 and 25 meter bands were very interesting in the mornings in those days. It was the first time and place that I heard that unique, fluttery sound that marks that Asia/Pacific path on those bands in the morning. I first heard the multi-path, echo signals during that period also. I often wondered ( still do ) if perhaps I was hearing signals both long and short path at the same time. It was during that period that I first heard the VOA relays from the Philippines and from Okinawa. They were loaded with echos to the point that the first few times, it was difficult to understand them and pick out the ID!

There was one other thing that sometimes made them difficult to identify. It was the first time I heard jamming signals and actually figured out what they were. They were most often heard on the VOA relay station frequencies. After I figured out what they were, I realized I had been hearing some of that on the 31 meter band, too, mostly during the evening hours. In those cases, I was not able to hear the station beneath the sounds at all and could not even tell what was being jammed.

It was during this period that my parents found they had traded one morning difficulty with me for another. Instead of trouble dragging me out of bed, they had trouble dragging me away from the radio to catch the school bus on time!

About this time I began to start “targeting” stations. I would read the DX columns in Popular Electronics and concentrate on the loggings at the ends of the columns. I would pick out a few, look at the times they were being heard and “lie in ambush” for them. Of course with this receiver, that was particularly difficult because of the total lack of frequency readout, but I began using the usual suspects on the bands like beacons just as I had before on the broadcast band. I would look for the interval signals.

I also figured out that it might be easier to find the “out of band” or “edge of band”stations more easily because they would not be in the thick pack. It was that way that I found Cairo and Israel at the lower extremes of 31 meters. I think Tel Aviv held forth on 9009 kHz at the time, if memory serves.  ( that is a good technique for finding some good DX even today!If you have a simple receiver without a lot of selectivity, hunt away from the big packs!)

Tuning the home built receiver was always difficult at best and often the tuning rate was a bit fast for trolling for the weak ones. I tried putting a larger knob on the tuning shaft and that helped some. I also developed a two-handed tuning technique that helped overcome the less than smooth operation of the dial-string-and-drum tuning arrangement.

The big problem that was coming to the fore was the lack of selectivity of the receiver with its single IF stage and no filters. A bit of reading in an older Radio Amateurs Handbook at the Waco Public Library gave a few clues on things to try. There was an article in one of the books about coupling between tuned circuits in IF amplifiers that gave me an idea. I probably shouldn't have done it, but being a kid, did not think about the possible consequences, but I removed the shield cans from the IF transformers and saw that the coils for primary and secondary were wound pie fashion on a horizontal wood dowel and were fairly close together. After reading about the effects of coupling on selectivity, I decided to try to loosen the coupling and see if that would help.

Luckily the glue on the windings was not too tight and they both sprang free with out much twisting. I was probably very lucky I did not break the tiny wires leading to the windings. I moved them as far apart as possible, out to the ends of the horizontally mounted dowel. That was for the input transformer to the IF stage. I did the same for the output transformer and replaced the shield cans.

The trimmer capacitors for aligning the IF's on this rig were on the bottom and had to be reached with a screwdriver from the bottom of the chassis. I had a feeling the movement of the coils might change the tuning, so I peaked those trimmers on a steady local broadcast signal. There was some improvement, noticeable right away. The peaks seemed a little more well defined. I was afraid that the decreased coupling would reduce the gain of the stages too much, but that fear quickly disappeared. There was a just noticeable drop in signal level. I found the improvement noticeable in trying to separate some of the close packed signals on 31 and 41 meters the first night.There were some new loggings right away, and looking back at my “ stations heard list” from those days, I found a note where the modification was made, so even years later its easy to tell the difference it made. Some of the stations had been covered by strong VOA or Radio Havana signals. I was able to dig out Vatican Radio, Radio Prague. Austria and Deutsche Welle ( the latter might have been audible but just not identified before). It might have been frightening to know just how broad the tuning might have been on that thing before the change!

I also found the idea of “targeting” stations by looking up their schedules and frequencies was productive for finding “ new “ stations I had not heard before. Some of these were not really buried in the crowd, but had just been missed because I was stopped during band sweeps listening to a program that sounded interesting. Looking back, it seems almost odd that it was only after several months of listening that I found Radio Nederland from Hilversum, Holland given how strong it was. The same for Italy's RAI.

One disappointment to this day are the Scandanavian countries that are now absent from the bands and cannot be heard today. They were on the air then, but even though I lay in wait for them, I never did not log the stations from Denmark, Sweden, Norway or Finland during those glory days of short wave listening.

The improved selectivity of the receiver also made listening in the amateur bands much more enjoyable. Previously the crowded bands filled with predominately AM signals were a cacophany of whistles and squeals of carriers beating against one another with high pitched heterodynes making listening difficult. The narrower tuning began to make many weaker signals audible and tuning the 40 and 20 meter phone bands became much more pleasant and I began spending more time there. I was soon logging stations from all over the country, and from Canada and Mexico. Soon there were DX stations from the Caribbean and South America in the log for the first time.

Of course, improvements always lead to a desire for more improvements. I had read about another technique for further tightening up the tuning and providing additional gain: regeneration. This involved introducing a little intentional feedback in the IF amplifier. I was already somewhat familiar with the idea from my little one tube “ little howler” receiver I had built from a kit a couple years before. Soon the receiver chassis was once again turned over and this time the soldering iron was out. I had read about a simple method for introducing regeneration by soldering a short piece of insulated wire onto the plate pin of the IF amplifier tube and moving it close to the grid pin. The article cautioned about not getting it too close or full oscillation would take place.

The soldering job did not take long and soon a one inch piece of wire with insulation still in place on the free end had appeared on the bottom of the 12SK7 tube socket. Firing up the receiver soon showed what the author had meant about oscillation. Wild squeals burst from the speaker of the radio!. It took careful movement of the wire away from the grid lug using a pencil ( receiver was on and high voltage present on the plate lug!!) to reach the point where there was some feedback, but not enough to break into oscillation on weak signals. ( I learned later that the automatic gain control bringing the gain up on weak signals would increase the possibility of oscillation, just like turning the gain up on a public address system will do the same with audio).

Once again, peaking the IF tuning adjustment was done. The results were amazing. Just tuning the IF's made the change very obvious. The peaks were very sharp, with only a fraction of a turn resulting in a peak being found or lost. There was also what would later become a familiar sound, the swishing in the audio as the peak was swept past.

This turned out to be the biggest improvement made in the receiver to that point. Tuning was noticeable sharper and any gain lost by decreasing the coupling before was more than made up. Now we were getting somewhere.

But something else came of the experience. I found that by moving the coupling wire back and forth to intentionally get the receiver into oscillation, cw signals were suddenly audible. I had just begun to study the Morse Code with an Ameco course on a record and had been wondering how long it would be before I could afford an actual amateur receiver to hear code on the air. There would be no wait. It turned out that a plan to improve my existing radio led to something totally unexpected of it: the ability to hear cw. A major door had opened.

Loop the Loop

The idea of using loop antennas to minimize interference and to help dig weak stations from beneath stronger ones on the same frequency may be old hat to many, but the idea evolved for me. Like many other things in my younger days of DX-ing, without a local mentor or access to a lot of printed material, it was a learn as you go process.

The upside of all of that was while learning, I also figured out how to get the effects of a loop without spending a lot of money. Many today may look longingly at some of the commercially built loops for sale or at the projects in publications or on line and find the cost of the loops or the materials puts the idea out of reach. However if one finds it acceptable to make a few compromises that reduce performance only a little or provides a product with something a little less polished in appearance, the cost can be reduced to almost nothing.

My first inkling of the directional affects of loops came when I was using one of my very earliest receivers, my old trusty Watterson five-tube broadcast set. It had the requisite loop on the back and I noticed that when it was placed on the side of my desk to my left, some stations were not as strong as when it was on the desk in front of me, or rotated 90 degrees.

At first this was an annoyance more than anything, because it meant that to hear my favorite Chicago station at night ( of course in the early sixties it was WLS!!) the radio had to be to my left, making use of the desk for homework and other things a little awkward. There was still no clue planted to use the effect to find other stations. Then when I began using an outside antenna connected to the radio, the effect was overridden and more or less forgotten about.

It was when my younger sister got her first portable transistor radio that the impact of a rotatable loop began to be driven home. She received a high quality eight-transistor radio for Christmas one year that was not only highly sensitive, but selective as well. It had an RF stage and two IF's and was small enough to be portable, but large enough to have a five inch long ferrite loop in the top of its little cabinet.

Somehow I managed to get her to let me use it to listen one night...probably with the promise of a couple set of batteries since it went through them like water. Sitting at the the desk, it could pick up stations that the Watterson without the outside antenna could not separate. I was a little annoyed at first that there was no way to connect my outside wire antenna to it and the thought of opening it up to find a way to attach it to the circuit was not an option with my sister watching very closely what I was doing with her prized radio.

The effects of the internal loop on the little radio were amazing to me. First of all, the little radio was picking up by itself most of what I could hear on the Watterson with the outside antenna connected. Rotating the radio did not produce much of a peak in signals, but the nulls were amazingly deep and I could almost make local stations disappear. It was easy to hear KLOU form Lake Charles, Louisiana on 1580 khz despite the presence of a local station, KBGO-AM on 1580. For the first time I found that I could pick out stations on some of the crowded regional channels, in some cases logging two stations and in one case three stations on the same frequency.

I only had the little radio for an hour or so before my sister demanded it back, but a lesson was learned. At some point, a loop antenna would be an asset.

It was a few years later that the next lesson was learned when I was a college student at the University of Houston. My roommate had a Hammurland Super Pro receiver that he had been working on but we didn't have an antenna to connect it to. There was no way to string a wire outside the dorm as I had done while at Texas A&M ( a whole 'nother story!!!) and he wanted to listen to some broadcast DX. I remembered lessons in a radio-tv correspondence course my dad had taken that described tuned loops, but the details were a bit hazy. I remembered that they involved a resonant tuned circuit for the loop and a link coil to provide a low impedance connection to the receiver.

We had some insulated wire and scrounged a broadcast band variable capacitor from an old radio and went to work. But what to make the loop out of was the question. We both spotted a yellow plastic trash can at the same time. Why not? We started out with 15 turns of wire lengthwise over the top and bottom of the trash can and attached the variable cap to make it a parallel tuned circuit. The turns were spaced about a quarter inch apart with the ends of the windings anchored by punching holes in the plastic near the top of the can with an icepick. The coupling coil was spaced over a couple inches and had two turns. We ran a short piece of RG 58 coax we had from the link to the receiver.

The first try near the top of the band resulted in signals, but not too strong. Rotating the capacitor did not result in a peak. Obviously our wild guess on number of turns was off. Checking at the bottom of the band resulted in a peak with the capacitor almost completely open. Obviously too much inductance was the problem. We started removing turns one at a time and when we got down to eleven turns, we could get a peak at the top of the band but not quite at the bottom. The capacitor was of the two gang variety, so a clip lead to parallel the two gangs resulted in a successful resonating at the bottom of the band, and the top could be reached by unclipping the jumper.

The whole project took about thirty minutes. A pretty good null could be obtained and the sensitivity was pretty good. All the “ usual suspects” could be heard...the Chicago stations WLS, WBBM. WGN, WMAQ all were in good...as was WSM Nashville, WWL New Orleans, WLW and WCKY Cincinnati. As a bonus, it appeared that a good bit of the flourescent light noise was reduced.

This was the beginning of my own love affair with the improvised loop. While I have made some “ serious “ loops, including a wood framed three foot wide beauty my dad helped me build years later, to loops inside plastic pipe in a round shape with a neat tuning box at the bottom, there have been many times I have put together impromptu tuned loops almost anywhere. Many times while on engineering trips I have put one together in a hotel room to do some DX-ing or to get rid of noise. Many times these were wound around cardboard boxes of various sizes, a few times around trash cans, and even once around a door ( opening and closing the door had the effect of “rotating” the loop!!)

While some very fine, pretty and well performing loops can be purchased if you want to spend as much as $300, some pretty good performance can be had for next to nothing. The size is not critical, though less than a foot across is about the smallest I have gotten really good DX results with. I can't provide you with exact numbers of turns for various sizes, that can be determined experimentally, thought I would imagine there are formulas that could be used to determine. However the time and effort to do that are greater than just winding one and either adding or taking off turns to get it to resonate.

These impromptu loops don't require exotic materials other than a broadcast variable capacitor. I will admit these are getting harder to come by in recent years, but anyone playing with radios for any amount of time probably has an old tube junker around that could be cannibalized. One could be ( Gasp!) bought through a mail order parts house and kept for DX “emergencies”. Some of these are probably good to have around for various things in a well filled DX-ers junk box anyway. I usually start with ten or eleven turns and just hunting for the resonant spot. An old fashioned grid dip meter could be used to find resonance very quickly. I have never tried one of the fancy new ham antenna analyzers or a loop and am not sure what one of those would really tell you anyway. Maybe someone who knows or who has tried it might add a comment to this blog with their experience.

Impromptu loops are inexpensive and can “grow” anywhere. They are particularly good when traveling precludes carrying a lot of stuff on an airplane ( or doing so would raise eyebrows in the security check!!!).

Coupling to the loop can be done either with feedline or inductive coupling by placing a portable receiver with an internal loop next to the larger loop's windings. I actually did just that using the table top clock radio in hotel room on a trip to the Bahamas once! The loop was wound on a plastic trash can and set on top of a small table in the room and the loop and radio moved around the table for rotation.

While the homemade impromptu loop might not give quite the full performance of a commercially made device or the more complex big ferrite core loops in some ways, its practicality and availability for use outweigh those issues. After all, the idea is “ DX With What You Have” and “ DX Anywhere, Anytime”

By the way,. By adding more turns, these loops do an excellent job on long wave frequencies and work very well for NDB DX-ing, and with fewer turns do the same in the 160 meter amateur band and the lower tropical bands ( 120 and 90 meters) They don't seem to do much better than a random wire up higher.

Have fun!

Auroral Effects-BCB Possiblities

Many DX-ers might look at aurora as a problem.  The band is dead, higher frequencies are filled with flutter, the usual suspects are gone.  But the recent activity has opened another door.

Recent high level auroras due to solar storm activity and mass ejections have affected prop on Earth. The first effect was noted while making my morning BCB band scan on the way to work.  I usually leave home about an hour before sunrise in winter and spring.  Day to day, I notice some differences in prop, but the pattern is usually similar.  The usual " friends" show up.  Sometimes the lower frequencies are not so good and the Chicago stations on 670, 720 and sometimes 780 are weaker, with 890 being stronger.  Comparisons of them is my usual "barometer" for what is happening. If 670 and 720 are weak,  I run more through the higher frequencies and they usually are OK.

In those cases 830 from Minneapolis will be weak, but 1500 from St Paul ( just  "next door") will be strong, as will be 1530 from Cincinnati.  Closer to sunrise,  840 from Louisville will be weaker as will 750 from Atlanta and 870 from New Orleans. That will leave Mexican stations audible.  If Atlanta is already gone, there is little chance of hearing Cubans because the sun is already up there.
If the closer stations are strong,  the Cubans or South Americans will not be audible.

At the same time, 850 from Denver and 1160 from Salt Lake City will be in as the Eastern stations disappear as the sun is rising in those areas. The Eastern Time Zone Mexican stations disappear and the Western more stations start appearing.  Its a matter of letting the sun become a  "barrier" to let different stations be heard.

Some mornings the skip is still uniform,  just shorter.  On those mornings I will note that Kansas City on 710 will cover Amarillo, with 810 and 980 from Kansas City also rolling in.  On those mornings, 880 from Lexington, Nebraska will be in strong as will 580 from Topeka, Kansas.  Shreveport on 1130, Tulsa on 1170 and St Louis on 1120 will be particularly dominant on their channels. Other mornings Mexican stations might appear either behind them, or sometimes even above them.

But on a strong auroral morning, things are very different.  The northern stations are gone. There are no Chicagos, no Minneapolis,  no Louisville, no Salt Lake, maybe even no St Louis.  Even in the earlier hours well before sunset, these "regulars" will be totally gone here in Central Texas.

Is the band dead?  Absolutely not!  At his latitude, the auroral effect is only on those stations in or not too far south of the zone. What happens is that weaker or more distant stations to the south or on my own latitude that are normally masked are suddenly available.  Cuban channels normally blocked by strong US stations are suddenly in the clear.  many might be lower powered stations. Normally unheard  Mexican stations or even Central or South American stations appear.  Stations from the Southwestern US are in,  not stronger, just no longer covered.

An enterprising DX-er in moderate latitudes would do well to keep an eye on Space Weather dot com or other sites that post warnings of solar activity.  Just as VHF amateur or TV and FM DX-ers watch weather maps for approaching cold fronts,  BCB DX-ers should watch solar weather for opportunities or times to particularly try to be tuning in.  You can take advantage of an auroral "curtain" to log some new ones,  just as we daily use the sunrise or sunset lines as curtains to block strong signals to allow weaker ones in.  The main difference is the sunset/sunrise lines are generally for East/West advantages, but the auroral curtain will be for North/South advantages.

Aurora also provides some rather unique opportunities for VHF DX-ers,  but that's a story for another day!

( Listening here is done in Central Texas with home receivers now being an ICOM R-75, Hallicrafters SX-96, Yaesu FT-757-GX, Drake 2B, Hallicrafters SX-111, Hammurland HQ-170,
Mackay LF maritime receiver and BC-342. Antennas are a 95 foot top fed sloper up 45 feet, a 130 foot Inverted L with 40 foot vertical section, various short verticals and a 3 foot home made box loop. Mobile listening is done with the standard receiver in a 1999 Ford Ranger pickup)