Dxers Unlimited's mid week edition 3-4 March 2003

By Arnie Coro

radio amateur CO2KK




Hi amigos radioaficionados around the world and in space !!! Welcome to the mid week edition of
Dxers Unlimited , your favorite listener oriented radio hobby program. I am Arnie Coro, radio
amateur CO2KK, and as always it is my pleasure to share with you almost eighteen minutes of on the
air time !!! Here is item one: Spring Equinox just around the corner amigos, and we are just now
seeing some very interesting DX conditions due precisely to the approaching equinoctial propagation.
Item two: Short wave listening, that is listening to short wave broadcast stations is one of the
many ways you and I continue to enjoy this hobby on a daily basis... I spend at least an hour a day
monitoring international short wave broadcasts from all around the world, and after half a century
of been an avid short wave listener, it continues to fascinate me... Today I will tell you about how
to find new stations that are located in between the very powerful ones... Item three: You have
questions , yes you may have many radio hobby questions , so here is my advice, make a list of the
ones you want to be answered first and send them via e-mail to arnie@rhc.cu, again, arnie@rhc.cu, or
VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana , Cuba. Today I will answer a question sent in
by a listener in South Africa that picks up our Internet streaming audio. He wants to know more
about TV Dxing... Item four: The MOXON rectangle antenna continues to fascinate radio amateurs
around the world. The MOXON rectangle is a very compact two element beam that , when properly built
produces a perfect match to the typical 50 ohm coaxial cable, without the need of any adjustments
whatsoever. There is even a very small WINDOWS program that helps to calculate the MOXON rectangle
antenna... I have recently built two MOXONS, one for the 6 meter band, and the other for the 15
meter band. Both are made from no 14 copper wire, and have provided excellent results... More about
the MOXON rectangle antenna later in today's edition of Dxers Unlimited. Item five: HUM in power
supplies is unfortunately a very common problem, and there are many tricks of the electronics trade
that you can learn and apply to minimize hum in the power supplies used by your radio equipment. A
visit to Arnie's workshop will take you trough a very simple procedure that I apply to all power
supplies reaching my workbench... it takes little time, a few low cost parts and YES, they do help
to make HUM go way down or dissapear completely. AND AS ALWAYS, at the end of the show, stay tuned
for Arnie Coro's Dxers Unlimited's HF propagation update and forecast, the most up to date analysis
of short wave propagation conditions that extends to the 50 megaHertz band too... Margarita Delgado
is my sound engineer and producer , I'll be back in a few seconds... Stay tuned....

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You are listening to Radio Havana Cuba, on th air and on the web, with streaming audio from
www.radiohc.cu, again, you can connect to www.radiohc.cu and listen to our streaming audio amigos!

Now here is item two: Do you listen regularly to international short wave broadcast stations amigo ?
Sure, I am sure your answer is yes, as 99 percent of radio enthusiasts around the world spend at
least an hour a week or more monitoring their favorite short wave broadcasts. The fact is that the
world's ten to fifteen more powerful stations are the ones that most people listen to... as a matter
of fact a recent survey showed that 85 percent of the short wave listeners concentrated on picking
up just five stations on a regular basis... AND, by following that patttern, they are loosing lots
of interesting programs that are on the air too, coming from less powerful stations, that do require
better antennas and receivers to pick them up properly. Next time you start listening to short wave
stations , take a little time to tune very slowly between the channels in use by the more powerful
ones, and search for weaker signals... You will be surprised to be able to pick up very interesting
programs, including beautiful music that can not be found elsewhere. There are still many stations
around the world that somehow duplicate their local programming on a short wave frequency, usually
running 10 kiloWatts or less power, and using a rather simple antenna system... BUT, the fact is
that they can be heard, especially when propagation conditions are good, as during the equinoctial
periods... So amigos , this is the right time to scan for those broadcasters, and enjoy their
programming that is, as expected, very different from the daily offerings of the ten or fifteen big
ones !!!

Item three: You have questions,the popular section of the show, is devoted today to TV DXING , one
of the more than 68 ways that you and I may enjoy this wonderful hobby.. Answering a question sent
in by Darrel from Cape Town in South Africa, I must say that TV DX has evolved tremendously during
the past several years, as now many TV DXers have included satellites among their Dxing options. Not
too long ago, I received a very interesting e-mail at arnie@rhc.cu telling me about a TV DXer that
was able to pick up signals from a satellite that was very, very close to zero degrees of elevation
at his location. He wanted to know why sometimes the signals from the satellite TV transponders were
very good and sometimes very noisy, and the answer was that tropospheric ducting was playing a role
on that particular situation, making possible that the very low elevation satellite could be seen at
times with excellent signals. Amigo Darrel, the low band TV channels still in operation around the
world are your best bet for super long range TV DX via the F2 layer, and they also provide the
possibility of sporadic E propagation . High VHF band and UHF TV will only reach you via
tropospheric propagation, so its range is much more limited. Low band TV DX signals may be seen half
way around the world for brief periods during solar maximum years and at other times on some
specific paths that involve the so called trans-equatorial propagation at both sides of the Earth's
magnetic equator.

Hope this answers your question Darrel, and remember that for low band TV Dxing you will need to
install a fairly large sized antenna with a rotor , in order to be able to pick signals coming from
all compass directions !!!

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Dxers Unlimited is coming to you from Havana, and yes we do QSL here one hundred percent... Send
your QSL requests to arnie@rhc.cu via E-mail, or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba,
Havana, Cuba... And now here is item four of today's program: The MOXON RECTANGLE is a single band
directional antenna system that is finding more and more users around the world. The reason for the
raise in popularity of this particular design of a two element beam antenna is that it offers three
very distinctive advantages over a typicla two element Yagi. Number one, it is smaller in physical
size, so its footprint is also smaller, and the antenna can then fit into places where a
conventional two element full size Yagi can not be installed. Second: The MOXON rectangle when
properly built and installed, has an outstanding, almost record breaking front to back ratio,
producing a very sharp null to the back of the main beam. and Third: The MOXON rectangle antenna
matches the typical 50 ohm line impedance almost perfectly, without requiring any additional
matching devices of adjustments. Now, let's see why many radio amateurs around the world are using
the MOXONS... take for example a ham radio operator that is a dedicated Dxer, spending most of his
or her on the air time on the 20 meters or 14 megaHertz band, the most popular one of them all for
dxing. The MOXON Rectangle , built using a very light structure and wire elements will fit into a
footprint about two thirds of the area required for a conventional beam, and because it is a very
light structure, it can be raised higher, thus lowering the take off angle, something that will of
course, bring in more DX... Now here is case two: Another amateur that wants to reach a repeater
located to his South, while at the same time avoiding the activation of a repeater on the same
frequency located to the Norh of his location. The deep null, that can be as high as 30 decibels
,provided by the MOXON rectangle , will guarantee that everytime he attempts to activate the 2 meter
band repeater, the one that will

be activated will be the right one.... A typical Yagi antenna , even with a large number of elements
will not give such a sharp minimum signal to the back of the main beam, that's a feature that only
the MOXON with its unique characteristics can provide. Finally , the MOXON rectangle can be very
easily calculated nowadays, thanks to the existence of a very small and effective software program,
that will take into consideration the diameter of the elements, allowing for extremely flexible
designs. One can make broad bandwith MOXONS for the VHF bands using large diameter tubing, or make
narrower bandwidth antennas using just plain good old copper wire. The MOXON antenna can provide
radio amateurs with an excellent antenna system that is easy to homebrew, still easier to adjust, as
it does not require any adjustment at all if made according to the dimensions specified by its
designer. A typical MOXON rectangle can be built in a few hours, using an X type of spreaders
arrangement, either made of fiberglass rods or PVC tubing . My 6 meter band MOXON uses two
broomsticks as the spreaders, and is made using no 14 bare copper wire. When compared to a much
larger and heavier two element Yagi built with aluminium tubing, the MOXON is a real winner, and it
is so lightweight that it can be hand rotated very easily. Si amigos, yes my friends, oui mes amis,
the MOXON rectangle is an excellent single band antenna, so easy to make that you can build one for
each of your favorite bands !!! The simple program to calculate the MOXON is freeware, and I can
send it to you as an e-mail attachment. Just send for the MOXON CALCULATOR program to arnie@rhc.cu,
and I will send it to you . It is a very simple WINDOWS program that you will learn how to use in
just a few minutes !!!

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An now amigos , just before going QRT here, at the end of the show , here is Arnie Coro's Dxers
Unlimited's HF plus 6 meters propagation update and forecast