Can you imagine a world without cable or satellite TV? A world where there might be only one, two or three local stations to watch and no "specialized" movie or sports channels even in existence? Travel with us now to those thrilling days of yesteryear filled with analog, black and white television.
It was in the very early sixties. I was still in my pre teen DX-in nyears, tuning the broadcast and shortwave bands with a table top Watterson BCB set and a little National SW-54 VERY basic general coverage receiver. And spending most summer days at my grandmother's house watching tv and enjoying all manner of good food, including home made kolaches.
But one day I made an accidental discovery that brought a whole new dimension to my young years of DX-ing and filled a very exciting summer.
Even during the time I was chasing DX
on the standard broadcast band and shortwave, it never crossed my
mind that TV was for anything other than entertainment. I mean, I had
seen a column on TV DX in Radio-Electronics magazine. But we had such
trouble getting to watch TV stations from Dallas about 90 miles away, and
the idea of actually receiving signals from great distances just
seemed like something that happened only under very freakish
conditions.
At my folks house we had been
satisfied watching two local channels with rabbit ear antennas. I
had put up a ten element high band VHF yagi on a twenty foot mast
that had been our only lifeline to tv during our short time living in
West Texas. We had lived in Coleman with the only station available
for viewing being KRBC on Channel 9 from Abilene, about sixty miles
from our house.
When we moved back to Waco and while
my dad was building our house, the antenna was folded up and lay on
the ground with its mast. But as a kid wanting to watch more TV than
just on the two networks available on the two local channels we had (
there was no such thing as cable TV in our area then) I was always
trying to figure out a way to get more channels. Channel 4 from
Dallas would sometimes come in with a snowy picture on the rabbit
ears. Channel 8 was more difficult. It always seemed that the “good
“ shows were on those channels and not on our local two. Channel 11
was the real prize because it was an independent station in Ft Worth
that carried old movies. Even if it would have been strong enough to
give even a snowy picture, our local channel 10 would have covered it
up with the almost non-directive rabbit ears.
With my dad's help, I got the twenty
foot mast up beside the back of the house with the 10 element single
channel yagi on top. It gave a watchable picture on channel 8 and in
the evenings a decent picture on channel 11. In addition to the
greater signal strength due to the gain of the antenna, the
directivity helped to knock down the overwhelming strength of the
local channel 10 which was almost directly off the side of the
antenna. That summer, our local channel 10 also moved its transmitter
site from its relatively short downtown tower about ten miles from
our house to a taller, 1000 foot tower that was almost 25 miles away.
Even with the greater height, it was not so overwhelmingly strong.
I can't even remember where it came
from, but that summer I also came up with a three element low band
yagi. I may have traded something to a friend for it. I really don't
remember. But it went up on the mast as well. It did not really
have enough gain to give fully reliable pictures on Channel 4 from
Dallas, but in the evenings it was watchable with some graininess.
My grandparents lived about a mile
down the street from us. They had an outdoor antenna on their roof,
probably thirty feet or so above the ground. I never really
understood it, but even though they were down the hill from us, they
always got better TV reception than we did. In fact, they got all
the Dallas stations just fine, 4 and 8 were good all the time and 5
and 11 from Ft Worth were also very watchable. The antenna was a
very simple single bay conical. This was the most basic of antennas.
At a time when every house in town had a telescoping mast with
varying amounts of educated aluminum tubing on top, it was fairly
small in comparison to most. But it performed very well.
For that reason, in the summers, my
sister and I would often spend the day with them while my folks
worked. ( Well, OK, they were technically baby sitting ). There were
days that I could ride my bicycle back up to our house for an hour or
two of listening to the radio, but meals, TV and a good supply of
home made Czech kolaches kept us close to Grandma's house a good bit of the
time.
It was on a late morning in June that
my new DX challenge came into being. The Channel 8 morning movie was
over and I had begun switching channels around looking for something
else to watch. Channel 10 had a quiz show, channel 11 was in the
middle of a movie that didn't look too good, so I continued on around
the dial, planning to work my way around to channel 4. This was in
the day of “detent” tuners. The channel knob had a hard stop for each
channel, manually tuned. There were no remote controls in those days. There were no digital numbers to punch it to change
channels. One had to actually turn the “ channel changer” around
to another of the 12 channels. Ka-chunk, ka-chunk, ka-chunk. I went
around. Nothing on 12 and 13, nothing on the UHF slot ( another
story about that! UHF channels were in those days tuned on a separate
dial. To get them, you tuned the main channel knob to the “UHF”
position, then tuned in the station on channels 14-83 on a separate
dial –it did go up to channel 83, then, before those frequencies
were snagged for cell phone use...none of them then either--. Once
you got a UHF station tuned in, you could access it with the main
dial, just by going back to the “UHF” position. Clear?)
As I was saying, I passed the UHF slot
and of course found nothing because there were NO UHF stations
anywhere near our area then. Our local channel 34-KANG had gone dark
some years before. But as I hit channel 2 expecting nothing to be
there-Surprise! An almost perfect picture appeared. What was this? At
times the picture took a roll, sometimes there were vertical bars
that rolled sideways through the picture. Sometimes snow would
pulsate through the picture or the audio would develop a whine almost
like a fluttery heterodyne.
But where had this signal come from? I
knew from looking at the TV channel lists in Whites Radio Log that
the closest channel 2 was in Houston, almost 180 miles away and
almost exactly off the back of the antenna. Waiting patiently, I
watched part of some old sit com rerun hoping to get a clue from
commercials or maybe an ID slide. I had already gone into the DX-er
mode.
It seemed like a long time, but in
reality was only a few minutes until the bottom of the hour and time
for a station identification. While in the DX-er mode, I was already
expecting the station to take one of its signal dips or flashes of
snow just at the critical time of the identification. But DX-er's
luck was with me. What a surprise it was when the ID slide popped up!
It was KDIX in Dickenson, North Dakota! North Dakota! I had not
even logged North Dakota on the standard broadcast band in several years of tuning around!
The ID came just in time, as both
horizontal and vertical bars began rolling through the picture and
the snow began coming in waves. The station was soon lost in the
noise.
I quickly ker-chunked the channel knob
up to channel 3 to see if there was anything there. There were traces
of something, but it was obscured by rolling pictures, rolling bars
and the sound was a scream of FM heterodynes ( sound in analog TV was
frequency modulated while the picture was amplitude modulated). I
figured there were either multiple stations coming in and QRM-ing
each other or I had missed the opening.
Going up to channels 4 and 5, and not
expecting much because the Dallas and Ft. Worth stations were
relatively strong, I was surprised to see signs of strong
interference. Both stations showed tearing of the picture at the
corners and horizontal bars rolling through the picture. Even the
local channel 6 whose transmitter was perhaps 30 miles away was
showing some wiggling and signs of faint bars.
After lunch I got permission to go up
the folks house and got out my stack of Radio-Electronics magazines.
I had almost a dozen going back a couple years. Not every copy had
the TVDX column, but enough of them did that I got a good idea as to
what was going on. It was Sporadic E propagation. This is the
reflection off relatively small ( small compared to the entire
ionosphere at least) highly ionized clouds inside the ionosphere's
E-layer of lower VHF frequency signals. At that time there was no
real theory as to what causes the formation of the clouds. Even
today, that is somewhat open to question. What is not open to
question is the fact that it happens, often in late spring and early
summer, but sometimes in other parts of the year. Sometimes only the
lower channels would be affected, but sometimes under highly intense
ionization, frequencies as high as the FM broadcast band could be
bounced back to earth up to a thousand miles away.
Even though I had seen the signal drop
out from the North Dakota station earlier, thought I would try at
the home place to see if something else might be coming in. I got
the idea of turning my little three element antenna sideways away
from Dallas to minimize the signal coming in from there and maybe see
something on channels 4 and 5.
The antenna ended up pointed just
about due east and though channels 4 and 5 were pretty well nulled
out, there did not seem to be anything there. However on Channel 2,
there appeared to be two signals battling it out. The audio sounded
like bees buzzing at times and the vertical bars were rolling
furiously horizontally across the screen as first one station, then
the other took over and came through. At about three o clock ID time
came around and beginner's TV DX-ers luck really took hold and I was
able to identify both stations as one faded down and the other
alternatively faded up...there were two Florida stations, WESH-TV
from Daytona Beach and WTHS from Miami. I am not sure if those same
call letters belong to those stations fifty years later, but I did
get a QSL verifying reception of WESH-TV.
After a half hour battle between the
two stations on channel 2, I finally got to look up on channel 3,
and quickly identified WEDU from Tampa just as signals started
dropping out.I turned the antenna back around to the north to be
ready for an evening's TV watching from the Dallas stations and when
I went back into the house ( the antenna was turned by the “armstrong
method”, rotating the entire mast by hand) I was surprised to see a
new station coming in on channel 3 where I had left the set...it was
identified moments later as WKZO from Kalamazoo, Michigan. It soon
faded away and continued checking of the low channels turned up
nothing more the remainder of the afternoon. But all in all, it was a
pretty exciting day for a first look at TVDX!
Over the next few days I read a lot
and learned a lot about VHF wave propagation. That learning process
was to extend over the next fifty or so years, and
continues on today. The same goes for any form of DX. One learns the
ins and outs of the conditions that bring it about and while not
necessarily understanding the physics of the situation, one can at
least learn to recognize them when they come up and take advantage of
them to get things in the log. But then, isn't that the aim, anyway?
The next morning was one of the first
in a long time that I did not head for the shortwave receiver.
Instead, even as my dad was getting ready for work just after
sunrise, I was in at the TV, looking for signs of distant stations.
The low channels were dead empty except for the local channels. The
Dallas channels were particularly snow free, looking better than
usual. Hand rotating the antenna around to the southeast, I noticed
the station in Bryan, about 90 miles away, KBTX on channel three was
coming in for the first time. This channel in the early sixties was
not a full power VHF but relatively low powered and on a short tower.
It served mostly as a relay or “satellite” station to our local channel
10, KWTX, only originating a few of its own local news segments.
They were even identified together.
On this same antenna heading was a
weak channel 2, but it did not have the same appearance as the
Sporadic E skipped channels of the day before. It was the station I
had suspected when I first saw a signal on channel 2 at my
grandparents. It was KPRC in Houston. It had the appearance of a
weak, distant regularly propagated signal. The fading was very slow
and deep, never really quite coming up to regular viewing appearance,
but without interfering bars. There was no interference to channel 4
which was still strong even off the back of the antenna.
Channel 5 showed a little barring or
herringbone effect, but it took turning the antenna around to the
southwest to get a recognizeable picture. That turned out to be KENS
in San Antonio. Houston was 180 miles, San Antonio a little less.
From what I had read about sporadic E, this was way too short a
distance. I had checked all the other channels up through the high
band of VHF and nothing was showing. I had hoped for a signal out of
Houston on their other channels, but it was not happening that
morning.
One thing to note about VHF TV
channels. They were actually divided into two bands, high and low.
The low group consisted of channels 2-6 and run from 54-88 mc, each
channel 6 mc wide. You will notice that the numbers don't really add
up. That's because there is an additional gap between channels 4 and
5. That gap is the home for some aviation navigational aids. These
are where the marker beacons on approaches to runways are located.
It also allows local allocation of channels 4 and 5 in the same city.
Other channels require a channel wide gap to avoid adjacent channel
interference. Directly above channel 6 was where the FM broadcast
band was located, from 88-108 mc. There was another gap, with
channels 7-13 being located between 174 and 216 mc. Those channels
are known as “high-band VHF” and channels 2-6 are known as “
low-band VHF”.
In the analog days, the picture
carrier signal was at the low end of the channel with the lower
sideband of the amplitude modulated carrier attenuated with a filter.
This created a signal known as “vestigial sideband”. The
receiver could detect the picture information with the carrier and
only the upper sideband. This conserved spectrum space.
The audio signal was a separate
frequency modulated affair. In fact it was generated by a separate
transmitter altogether. It was located 4.5 mc above the bottom of
the channel. This explained why on FM receivers, one could often
hear the channel 6 sound. The sound carrier was just below the FM
broadcast band and still within the range of most FM receivers. The
separate sound and picture transmitter outputs were fed to the same
antenna through a diplexer. There was also a filter to reduce the
strength of the lower sideband, to obtain the “vestigial”
sideband operation. This meant in TV transmitter rooms you could see
considerable piping in the ceiling as these filters and the diplexer
were often hung above the transmitters.
What I began to learn as I turned back
through the pages of the old TV DX columns and through the
previously unread VHF portions of the Radio Amateurs Handbook was
that there were several mechanisms for VHF and UHF signals to travel
long distances. Some involved the E layer with Sporadic E, some
rarely involved the F Layer just like regular short wave ( though
this was very rare) and some involved things happening in the lower
levels of the atmosphere as a result of weather.
It was interesting to note this
morning and subsequent mornings that this particular method had to do
with changing temperature. The previous night had been cold. During
the morning, it was warming rapidly.
The air is not warmed directly by the
sun. Our own local star sends out radiant energy which just passes
through the air. The sun warms the earth, and the earth warms the
air through conduction and convection. Thus sometimes in the mornings
there can be a layer of warm air at the surface, with cold air above
it. When a VHF signal passes through this boundary, it appears to be
bent slightly, bending back toward the earth and thus following its
curvature more than it normally would. As this layer thickens and
the boundary layer rises, it appears that the distances covered by
the bent signal increases, until a critical angle is reached when the
bent signal no longer returns to the earth.
That matched what I began to notice
over the years. This morning “enhancement” would occur not right
at sunrise, but a little after, peaking an hour or so later,
depending on the actual temperature difference between day and night.
Then it would just disappear.
That particular morning I decided to
try to search in a different direction, going around to the east.
Over the years I found that openings tended toward the east. I do
not know if this is because the sun has risen just a bit earlier in
that direction and the heating is a little more advanced or what.
It's not a scientific thing at all, just something I have noticed
over the years.
That morning I also learned even more
about minimizing local signals. As I turned the antenna to the east,
it put the ten element yagi's side toward our local channel ten.
Sometimes the front to side ratio of long yagi antennas can be quite
good, and on this particular morning it was good enough. A signal
appeared interfering with the local channel 10. There were the tell
tale horizontal bars rolling through the picture and the sound was
garbled with two fm signals obviously beating against one another.
After a few trips outside to make minor adjustments to the antenna
direction, the interloper signal gained the upper hand long enough to
be identified as KLFY in Lafayette, Louisiana. This was my first
high band VHF TV DX catch.
There were no sporadic E signals that
morning and in about another half hour, all the “enhancement” of
ground wave signals was gone. Looking back, I am guessing that this
bit of DX was the result of just such a temperature inversion. It
was a mechanism that would provide lots of fun over the coming years
not only with TV DX but amateur radio DX on the 2 meter band.
Later on day 2 of my TV DX career I
was somewhat disappointed in the beginning. At my grandparent's
house with the conical antenna, there was only one signal that came
through from the north. Just before noon there was a good signal for
just a little while from WLWD in Dayton, Ohio on Channel 2. It was
quite stable and watchable for about a half hour, then quickly
dropped into the snow. There were indications of other stations, but
none strong enough to watch.
After lunch that afternoon, I went
back to the other house and once again tried nulling the Dallas
stations ( the grandparent's antenna was not rotatable) This time I
got lucky. A station popped up and completely covered the Dallas
Channel 4 ( at that time the Dallas 4 was KRLD-TV). It turned out to
be a station that I would see many, many times during sporadic E
openings. It was WUNC in Chapel Hill, North Carolina. I don't really
know why it appeared so often. Perhaps it was in just the right place
and the E clouds formed repeatedly in the right place or what, but it
was visible many times that summer and in subsequent years.
That same afternoon, another North
Carolina station got in the log. It was WFMY-TV in Greensboro, North
Carolina.
A pattern began to show up. There
would be sporadic E openings to the north or northeast in the
mornings and toward the east in the afternoons. That next morning at
the grandparent's house signals came in from KDLO on Channel 3 from
Florence, South Dakota, from WGR-TV on Channel 2 from Buffalo, new
York, from KID-TV in Idaho Falls, Idaho ( there had actually been a
picture of the ID slide from that one in one of the magazine articles
I had read), from WBBM-TV in Chicago and rounded out by WBAY on
Channel 2 from Green Bay, Wisconsin. The log notes indicate that on
that morning, signals were up and down with at times three stations
swapping top position on a given channel. There were others that
were just never identified. Some were identified by actual ID slide
and others by locations mentioned in local commercials and checked
against the venerable White's Radio Log listings.
One thing I noticed while rotating
antennas over the years when pulling in Sporadic E signals, even with
bigger antennas in later times with much sharper directional patterns
than the small yagi I was using for Low Band VHF that summer, was
that the incoming Sporadic E signals did not peak sharply in
direction. I kind of wonder if this might indicate that they were
coming in at a rather high angle and perhaps striking more the top of
the antenna than the front. Again, this is not a scientific thing,
just an observational thing. This was a very useful trait in a way,
because the nulls on the sides of the antennas were always sharper
and it was often possible to null out a near local station enough to
pull in the incoming DX signal, even if the antenna was not really
pointed in the optimal direction for the distant station. As is
often the case when using a loop for Broadcast band DX, it is
sometimes more important to get rid of the interfering station than
it is to get a perfect peak on the incoming signal of your target.
The next few days were a little
disappointing. While there were some openings, the were shorter and
not as intense. I was also seeing some of the same stations I
already had in the log. There were a few more early morning high band
loggings as a result of some morning enhancement or temperature
inversions...KTBC Channel 7 from Austin which was a fair catch
because in those days they were on a short tower, and KTRK Channel 13
in Houston. I particularly remember them because they were not
running a simple ID slide. They had a short animated ID that had a
cat like creature that marched onto the screen and did a kind of roar
with the “KTRK”being its teeth!
That next weekend saw an opening that
made up for the slow Thursday and Friday. It was Sunday after lunch
and with the family all home, it would probably not have been a good
time to commandeer the TV for Dxing. However, the skip was so strong
that even with the antennas pointed toward Dallas, Channels 4 and 5
were so hit with distant station interference as to be be completely
unwatchable. Even the local Channel 6 had synch bars rolling through
it.
This kind of caught my dad's attention
and he listened as I told him about my adventures during the week. We
rotated the antenna around a bit to see what we could see. The
strongest signal I had yet seen from anywhere popped up on Channel 2
with the antenna pointed west. It was KNXT from Los Angeles,
California. It was strong and stable, just like watching the Dallas
stations on a normal day. It was in like that for almost two hours.
A check up and down the dial found a similar situation on Channel 5,
with KTLA from the same city also blistering in well for a couple of
hours. These signals were rock solid, with little flutter, fading or
glitches. It was amazing. And this on a three element antenna only
up twenty feet above the ground!
This was something else that would be
confirmed over the years. While antenna height is very important for
“regular” tropospheric reception and for temperature inversion
reception, it is not necessarily so for Sporadic E. Since the
signals seem to be coming down at a relatively steep angle, a lot of
height might not be necessary to get the signals. As long as the
antenna is fairly well in the clear and not totally hemmed in by
trees and buildings, the signals will get there! High antenna gain
is not really necessary either, as I have notice unbelieveably strong
signals from TV and FM stations and even amateur radio stations on 6
meters that come in by Sporadic E. I'm not saying that bigger,
higher gain antennas and greater heights won't get you more stations
or a shot at the weaker ones, but its not necessary to at least get
in the game.
That same day the pattern was broken
in another way. It was mid afternoon when KYW, Channel 3, from
Cleveland, Ohio came bouncing in along with KTWO, Channel 2, from
Casper, Wyoming ( another place I had not yet logged even on the
radio!)
That afternoon was marked by another
milestone: my first “foreign” TV DX as late that afternoon when
the other strong signals had all faded into the snow, a new one
appeared. It was eventually identified as XHFM-TV from Vera Cruz,
Mexico. That was somewhat strange because there were not even signs
of any other Mexican stations and the antenna was pointed almost
east. I don't know if this is an example or not, but there have been
times I have wondered if a signal did not arrive by scattering or
dual hop bouncing between first one E cloud, then the ground or sea
water and up to another E cloud. Over the years there have been some
real “dog-leg” antenna headings for some signals.
The next week, I decided to try to get
the antenna a little higher to “see over” some of the young trees
in the back yard. I found a large piece of water pipe with a
coupling in it and put another piece of pipe past the coupling. It
fit inside the bottom of the twenty foot push-up mast I was using. In
addition to getting the top antenna about eight feet higher, it also
allowed me to get more separation between the high band and low band
yagis.
I don't know if that is what did it or
if the conditions were just better, but that week, my station totals
for high band DX by morning enhancement took a big jump. After the
first group of stations came in, it also got me watching the weather
on TV and the weather maps in the paper more closely.
That Tuesday morning, by carefully
nulling the local Channel 10, I pulled in KZTV on Channel 10 from
Corpus Christi. The elusive high band VHF's from Houston came in as
KHOU, Channel 11 and KUHT Channel 8, the educational channel showed
up. KTRK Channel 13 returned with good signals.
While pointed in that direction a
check of the low channels brought a surprise with the appearance of
KPAC, Channel 4 from Port Arthur enough above KRLD Dallas for at
least an ID.
Turning back to the north, KXII
Channel 12 from Ardmore, Oklahoma made an appearance, along with KWTV
Channel 9 from Oklahoma City. Watching the weather on KWTV I noticed
them talking about a strong front that had passed them that would be
triggering thunderstorms along the Texas-Oklahoma border later in the
day.
That got me to thinking about the
bending that occurs at the boundaries between warm and cool air
during temperature inversions and was the first clue to me that
frontal boundaries could provide enhanced travel for VHF and maybe
UHF signals. Over the years I have noticed from observation that
they indeed appear to do just that. It has been my observation over
almost fifty years of trying to pay attention that signals crossing a
frontal boundary at a near right angle to the boundary appear to get
the most enhancement. Those crossing at shallower angles also seem to
get some help, but not as much. It also seems that sometimes the
path gets bent a little horizontally, with signals crossing the
boundary sometimes appearing to come from a slightly different beam
heading than you might expect.
Anyway, on that day, it seemed logical
as I had not seen those signals before while looking north. The next
day when the front had passed and brought rain to north Texas, the
signals were not there to be seen.
I had a chance to test the idea a few
days later when what was described as a cold front was approaching
from the north and west. The next morning I had the ten element
antenna pointing north west and swinging to the west at times ( I was
beginning to wear out the back screen door going out to turn the
antenna and wishing for an electric antenna rotor by this time!)
Sure enough, KRBC Channel 9 from Abilene ( ironically the station for
which the antenna was purchased to receive in the first place when we
had lived in Coleman) came in well, along with KOSA, Channel 7 from
Odessa in West Texas, a pretty long haul! After the front passed,
the next day, they were gone, but to the east, KTRE Channel 9 from
Lufkin was in as was KTBS Channel 3 from Shreveport.
That week had not been as spectacular
as the first week of Sporadic E DX but had been pretty important for
another reason. I was learning some valuable things about VHF signal
paths that would be very useful in the future. It also got me in the
habit of keeping a small notebook for things that appeared to affect
the signals. It created a habit of learning that has lasted almost
fifty years.
I noticed something else interesting
that day. It had been a full two weeks since I had even turned on
the SW54 shortwave receiver! It would thus mark another landmark in
my DX-ing career: finding different aspects of the hobby to study and
spend time with. That pattern would repeat itself through the rest of
my life. The focus would change from time to time, then return to
previous interests, keeping the hobby fresh and new over the years.
The next weekend was another
firecracker. There was a huge opening with what must have been
multiple E layer clouds. It was earlier in the morning than usual for
Sporadic E openings as I had observed them over my huge, two-week
career of TV DX-ing. That Saturday morning about 9 o'clock, I logged
my first Canadian as CBWT from Winnipeg came roaring in on Channel 3.
It did fit the pattern in one way. The first signals to appear had
come from the north or northwest. However, it was not alone as
several stations were fighting for supremacy on the channel. Over
the next hour and a half, XEZ ( absolutely certain of the call
letters because they were very visible three or four times) from
Mexico came in ( not certain of the city, it did not appear in my
White's Radio Log) but the biggie was CMKJ from Cuba. All were on
channel 3 and all were logged within a short period of time. Later,
KTVK from Phoenix came in on the same Channel 3 along with KPHO on
Channel 5, also from Phoenix. What a day! It was a good thing it all
happened in that short period because the family for some reason
wanted control of the TV that afternoon. Imagine that!
It had become apparent that the
propagation of VHF television signals were nothing at all like that
of short wave signals. But to summarize what I had learned in the
first couple of weeks work and reading: Clouds that formed in the E
layer were small and localized. There appeared to be no real short
skip. There also appeared to be times that there might be two hops
between different clouds. The one other thing that seemed apparent
was that the clouds did not move much. Stations seldom came and went
with regard to distance, but as the clouds disassociated, the
signals either dropped out or signals bouncing from other clouds
would replace them. It appeared that at mid-day the signals tended
to come from the north, then after noon till mid-afternoon would come
from the east. But this was not a hard and fast rule either.
Sometimes there would be openings to the west and no where else. I
had not seen many openings to the south, having seen only a couple
Mexican stations. I had seen only a little of the second form of DX
that affected the high band VHF channels through morning temperature
inversions or frontal passages. I had seen nothing on UHF, having no
antennas at all for that band.
I had already been a close observer of
TV antennas for several years. I had always been looking for ways to
get the more distant stations for entertainment purposes while our
family did not have either the cash or see the need for buying
antennas. I had watched roof tops and tower tops to note what kinds
of antennas people in the area were using. Many had been up since the
early fifties and were single channel jobs, some pointed toward the
local stations, some pointed at Dallas. Some had rotors, some had
multiple antennas on a mast pointed in different directions.
One other thing I noticed was when new
antennas went up. In one particular case, I noted that two large,
5-element low band yagis had been taken down and a new all channel
antenna touted as being a “ Waco Special” designed for the
channels available in our area had gone up. I also noticed that the
antennas that had been taken down were stacked against a fence in a
back yard. They looked in good condition and had not been put out
for the trash. I rode my bicycle down to the house and asked if they
would like to sell them. As it turned out, sort of like I had hoped,
when they learned I was doing experiments with television reception,
they took it as unusual something a kid would do and told me just to
take them. It two trips on the bicycle in a two mile round trip to
get them home. It was a rather awkward ride holding the antenna out
to the side with one arm and steering with the other. There were no
accidents and they were soon stacked against the back fence in our
yard.
I had wanted these antennas
particularly because they appeared to be cut for the lower channels,
probably Channel 4 if I had my guess. The small 3 element antenna I
had been using had obviously been cut for Channel 6 and was
noticeably smaller. The front to back ratio was pretty good for
Channel 6, but on the lower channels, 2 and 3, it appeared to almost
have more gain off the back than off the front. The length of the
reflector element was probably more close to the length of a director
on those channels and it easily could have been so. The “ new”
yagis” I had brought home were noticeably larger with longer booms,
wider spacing between elements and longer elements. They were also
twin driven, probably for wider bandwidth. Many antennas of the day
were like that. There were two folded dipole driven elements, one
slightly longer than the other. They were connected together with
metal bars that led to the connection point.
There was one thing missing. The two
antennas had been stacked for additional gain. But the stacking bars
that connected the two antennas ( sometimes called “Q-bars” by
one manufacturer ) were missing. They apparently had not been saved
when the antennas were taken down. I was not certain how long they
were supposed to be, if the spacing between them was critical and
how the impedances might match to the line.
It was back to the books to figure it
out. I went to the Radio Amateurs Handbook and the ARRL Antenna book
to try to figure it out. They had already been a help in making up
harnesses to connect the separate high and low band antennas I had to
a single feedline. We only had one run of 300 ohm twinlead running
under the house and up through the floor behind the television.
Reading about stacking of antennas, I
soon learned there were three concerns. Close spacing increased
mutual coupling and lowered the feed impedance. The signals from the
two antennas needed to be in phase to be properly additive and
provide the extra signal. And increased spacing meant greater gain.
Looking at my current situation, I
figured I could not put them more than fifteen feet apart. The
stacking harness would have to be made of twin lead and would
actually be longer than the spacing between them. After getting
deeper and deeper into discussions about matching, I decided to just
put them as far apart as I could mechanically manage, then use equal
length feed lines to connect them together, letting that be the way
they would be in phase and let the impedance chips fall where they
may.
The two new yagis were mounted on the
20-foot pushup pole with me standing on the roof. The top section
was telescoped down with the antenna mounted and twin lead harness
connected to the top one, the mast pushed up and an insulated
wooded standoff mounted seven feet down to take the strain off the
mid point feedline connection. The rest of the mast section was
pushed up to allow the mounting of the bottom yagi. The bottom yagi
might not have cleared the roof had not my extra extension been put
underneath the mast. Still it was close. That left two things for
concern about performance...the close proximity of the bottom yagi to
the roof and concern about impedance matching with the simply
convenient, though equal, lengths of the lines connecting the two
antennas.
The test was quick in coming. With the
feedline connected, KRLD, Channel 4 from Dallas was selected on the
TV and the antenna turned in the direction we already knew favored
that station. In place of the somewhat grainy, slightly snowy
picture we were used to seeing in the middle of the day with the old
3-element antenna, I saw a near perfect, local quality picture from
the station just short of 90 miles away. Turning the antenna 180
degrees resulted in a tremendous drop in signal. The station was
visible, but was deep in the snow. Turning the antenna 90 degrees
off axis resulted in no signal at all from Dallas. There was a
slight picture, which,with careful peaking turning up the San Antonio
Channel 4 above the threshold of identifiability but still deep in
snow. That was the first time that station had been seen without
morning enhancement. Channel 5 from San Antonio was likewise just
detectable. This was a great improvement! It was unfortunate that
there appeared to be no sign of a Sporadic E opening that day.
It was three days before any sign of
Sporadic E activity showed up. During the early morning hours there
were good signals from temperature inversion enhancement from San
Antonio, Corpus Christi, Houston and Port Arthur on the low channels.
That Friday, just before noon the tell
tale signs of E skip appeared. Synch bars began rolling through the
picture of the Dallas Channel 4. Running back and forth and rotating
the antenna toward the east turned up a pair of stations battling
for supremacy on the channel. The first turned out to be WFBC from
Greenville, South Carolina. The other station was maddening to
identify as over the next hour or so, every time a local commercial
break or ID possibility turned up, the Greenville station would turn
out on top. Rotating the antenna back and forth did not seem to make
much difference. Finally in one commercial break there were some
Florida references and the station was tentatively identified as WTVJ
channel 4 in Jacksonville, Florida.
Two hours had been spent on this one
channel identifying two stations and one was still just tentative.
It was time to check the other low channels and see if something
would be forthcoming. A check of Channel 2 showed only a slight
indication of a signal. Hand rotating the mast to the southeast
turned up not the usual KPRC channel 2 from Houston, but a Spanish
language station that was very strong, with only a few flutters and
occasional shallow fades. The ID when it came was unmistakeable: XEW
from Mexico City. Rotating the antenna around to the west had that
signal drop out, with no signal from San Antonio coming through south
and southwest, but a further strong signal from the west that was
soon identified as KORK from Las Vegas.
This was the beginning of a life long
interest in TV and VHF DX. In the coming years, further antennas were
tried. At one point, the antennas were supplemented by a 17 element
log periodic antenna at 40 feet. This provided much better day to day
reception of the stations from the Dallas area. It was easily noted
that while the antenna had higher gain and smoother response over the
entire VHF television bands, the front to back ratio of the LP was
not as great as the single channel yagis. The increased height was
of great help in reception of non-enhanced signals. However,
comparison between it and the antennas at the lower height during
temperature inversions and Sporadic E showed little difference in
performance on weak signals. With regard to Sporadic E, experiments
also showed that a single antenna sometimes performed better than the
stacked five element antennas, perhaps confirming the idea that
Sporadic E signals arrive at a fairly high angle. Stacked antennas
would have a narrower response in the vertical plane. More distant
stations might come in better on the two bay antenna, but ones not so
distant might actually be weaker on the two bay antenna as the higher
angle signals would be discriminated against.
I have often wondered if the same
thing might not happen with temperature inversion signals. One thing
that has been noticed over the years is that inversion enhancement or
morning bending can actually reduce the signal strength of nearby
signals by bending them away from their normal path. It was not only
on tv signals. I noticed it on 2 meter amateur signals in the late
seventies. At that time, while living and working in Port Arthur, I
often had occasion to drive back and forth to Houston both in the
evenings and in the mornings. During morning enhancement running only
15 watts on two meter FM, it was often possible to work Port Arthur
base stations running similar power from the west side of Houston. A
group of us operated simplex on 146.58 mHz.
There were two or three amateurs in
Port Arthur who would talk with me as I drove in from Houston and at
least one in Houston that would talk as I drove away from him. During
non enhanced times, stations from Port Arthur were not even audible
on the west side of Houston. In the times about an hour after
sunrise, they would be quite strong and easily audible even through
traffic, under overpasses and through areas of tall buildings in
Houston. However, as I got closer to Port Arthur, usually from the
vicinity of Baytown to near Winnie, I would lose the signals for a
stretch of twenty five miles or so. This area was usually easy to
communicate from during times of non-enhancement. It was also
interesting that a little further down the road, the station from
Houston would become inaudible, only to become readable, then very
strong as I approached Port Arthur. In the case of that station, it
would become inaudible in an area that was usually good for him
during non-enhanced times and would come back in about the area where
normally he would be lost without the enhancement. No scientific
proof or reason for this, just empirical data. I saw this happen on
dozens of occasions. I have also noticed it in the reception of FM
broadcast stations while driving on the road, having a station in
well, then having it fade as I would get within 60 or 70 miles of
the transmitter, only to have it come back in again closer in during
enhancement, but having it audible at the same location again during
non-enhanced times.
There is much I learned about VHF
signal propagation in the coming years, including other methods of
enhancement like dry line crossings, coastal bending, ducting along
coast lines and meteor bursts. There were also further experiences
involving UHF TV signals going well beyond normal distances.
In those early days and in days to
come, there was a lot to be learned purely be experimenting. Part of
the “art” of TV DX-ing is in minimizing the signals from the
“normal stations” I could see, trying to give the weak, more
distant stations a chance to be logged. Back in the sixties, all
television was transmitted with horizontally polarized signals only.
One was to minimize local signals other than turning an antenna away
from them was to mount a yagi vertically. The cross polarization
loss would take the signal down significantly. That along with
turning the antennas to face 90 degrees away from them would really
give the incoming skip signals a chance. Those arriving by Sporadic
E wold be all tumbled and of random polarization anyway, and chances
were being vertically polarized would with the receive antenna would
not reduce the chances of logging a good one. These days, that won't
work as most stations are now circularly polarized.
There have been times during Sporadic
E openings that I have experimented with wire beam antennas to try to
get more gain. On one occasion, I strung a rope up about twenty feet
high running from northwest to southeast trying to get Mexican or
Central American stations. I used wire elements that were actually
in an inverted V shape with insulators on the ends and nylon string
holding them out. The day I logged a Costa Rican station I had 12
elements strung from it.
There were other times that I did not
have access to real TV antennas at all and still managed to log TV DX
signals. In 1974 while in the Army after coming back from overseas, I
spent about a year at Fort Polk, Louisiana. I was assigned to
Headquarters Company and lived in an upgraded World War II barracks
building. There were individual rooms and I was able to have my SWL
receiver ( at that time I was using a Zenith TransOceanic and a
National NC-190) and the Company Commander had allowed me to put up a
pretty good antenna for listening. I had a 125 foot longwire strung
between two buildings that was about 25 feet high. We were on the
crown of a pretty good hill.
There was rudimentary cable tv service
to the barracks buildings. It was actually little more than a
community antenna system. In fact those were in the days before
widespread cable tv programming. Signals were pretty poor on it and
it wasn't long before I got the idea of tying the longwire antenna to
the television just to see if even the semi-local signals would be a
little better. I had already tried the longwire antenna for FM
reception and had been really pleased at the results.
After trying various means of hooking
up the wire, I ended up using two antenna impedance matching baluns
hooked back to back. I hooked the longwire to one side of the 300
ohm side of one balun and grounded the other, then ran the 75 ohm
side to the 75 ohm side of another balun, and hooked the 300 ohm side
to the tv. There was no real scientific reason I arrived at this, it
was just a matter of trying different things after connecting the
wire directly to the tv caused some instabilities in the tuner.
The results were actually pretty fair.
On a regular viewing basis, the stations from Shreveport, Alexandria
and Lake Charles, Louisiana were all easily watchable with this
arrangement. With some fading during the evenings, the Channel 10
from Lafayette would come in fairly well, along with Channels 2,
8,11, and 13 from Houston. This was much better than the on post
community antenna which just provided Shreveport and Alexandria.
During on Saturday Sporadic E opening,
many of my old friends from earlier days showed up, including
stations from Florida and North Carolina. Of course there was no
rotating the antenna. It was just a matter of waiting for one
station to fade out and another to fade in. But it was DX-ing in a
place you would not expect. ( And on weekends at Fort Polk, Louisiana
in the seventies you took your entertainment where you could get it!)
I notice looking back at my log for
May 30, 1974, Channels 2,4, and 6 from Denver came in rather late in
the day, about 7 PM. Then a little later Channel 6 from Sacramento,
California was easily identifiable. It was visible and easily
watchable for well over an hour, not fading out until well after
dark. Sporadic E this late was something I had not experienced up
until this time.
Most mornings and evenings, UHF
signals were enhanced enough to regularly allow watching Channels 26
and 39 from Houston, Channel 15 from Lafayette, Louisiana and Channel
33 from baton Rouge, Louisiana, all on the wire antenna!
My last experiences with TVDX on more
than a casual basis came after I got out of the Army and took my next
radio broadcasting job in Port Arthur, Texas. I lived in a two story
garage apartment that turned out to be just perfect for a bachelor
radio addict. There was a garage, living room and small kitchen
downstairs and two bedrooms and the bath up stairs. The second
bedroom was small and immediately became the ham/SWL/DX shack.
The first antennas for TV I put up
were for UHF only. In fact, it was not so much for DX-ing that they
went up, but for entertainment. Cable TV was not then what it is
now with all of the abundance of non broadcast channels. While the
local VHF stations carried all three major networks and had strong
enough signals to be seen with indoor antennas, the closest
independent stations with old movies and such were in Houston, with
transmitter sites about a hundred miles away.
Over the next few years in the Port
Arthur location, TV DX began taking a back seat to other pursuits,
including amateur radio operations, including VHF Dxing, which is a
whole 'nother story. There were numerous observations of TV DX on the
UHF channels with a 40 element yagi up fifty feet. The major
experimentation done here was with feed line. A local electronics
store had a stock of old ladder line-300 ohm TV line with plastic ( I
believe styrene) insulators at about eight inch intervals. Replacing
the regular flat line with this ladder line made a tremendous
difference in signal strength on the Houston stations available at
the time on Channels 26 and 39 ( all that were on the air there at
the time).
With the UHF antennas being the only
ones up observations on that band were all that were there to be made
over the next five years. There were several occasions where there
were openings that allowed good viewing of the Austin and
occasionally Dallas stations. The Channel 15 from Lafayette and the
33 from Baton Rouge, Louisiana were also often visible. I regret that
job responsibilities, amateur radio and teaching radio classes pushed
TV DX-ing aside during this period because I believe the proximity to
the coast would have provided some great opportunities for logging
even UHF stations at great distances. On other VHF and UHF bands
openings across the water of the Gulf of Mexico down the coast of
Texas and over to Florida were noted many times on the amateur,
maritime and public service bands. Observations included enhanced
long distance reception or transmission over long water paths and
along the boundary layers between off shore and on shore air. But
more on those in other chapters!
Suffice it to say, exposure to TV DX
led to learning that very long distances can be covered on occasion
by frequencies that would never be imagined possible, either by
Sporadic E propagation or by tropospheric bending of one kind or
another. In future times, signals on the VHF bands, either amateur or
other, have been noted well over a thousand miles. Signals in the
UHF range have been noted almost as far, though on less frequent
occasions. And there have even been great distances noted on a few
occasions as high as the 800 mHz public service band and one notable
occasion in the 900 mHz Studio to Transmitter point to point band. DX
adventure is indeed available almost anywhere you look for it!
