Re: [HCDX] Dxers Unlimited's weekend edition 20-21 January 2007

["Prof. Arnaldo Coro Antich" <inforhc@xxxxxxx>]

Radio Habana Cuba
Dxers Unlimited
Dxers Unlimited's weekend edition for 20-21 January 2007
By Arnie Coro
radio amateur CO2KK

Hi amigos radioaficionados... with our traditional salute to the world's 
radio hobby enthusiasts, it's my pleasure to start today's weekend 
edition of Dxers Unlimited, coming to you from sunny Havana, Cuba. I am 
Arnie Coro, radio amateur CO2KK and here is item one of today's menu 
Saturday morning, when I was starting to write today's script, I was 
enjoying VHF meteor scatter propagation , with several  excellent 
displays of channel 2 TV stations coming in for periods of up to 30 to 
50 seconds... YES... it's a not a meteor shower,it's just the daily 
regular background meteors activity, nevertheless significant for TV 
Dxers wanting to add new stations to their logs...
By the way, TV Dxing using meteor scatter propagation is always better 
starting around 2 hours before local sunrise...
Item three: Also meteor scatter propagation related... Answering a 
question sent by a Canadian listener ... he wants to know what's the 
best TV antenna for picking up channels 2 to 6 via meteor scatter 
propagation.... The answer in today's
ASK ARNIE, as Dxers Unlimited's weekend edition continues in just a few 
seconds after a short break...
......

Si amigos, this is the weekend edition of your favorite radio hobby 
program, the one and only that covers all aspects of this wonderful way 
of spending our spare time : RADIO... from extracting the minute ammount 
of energy captured by a wire antenna to feed a radio's audio amplifier, 
to recording the meteor refracted signals reaching a TV set tuned to an 
empty channel 2 or 3... from accepting the challenge of operating an 
amateur radio station at the below 5 Watts power level,that is running 
at QRP or very low power output levels, to running to a disaster site to 
provide much needed emergency communications after "professional" 
systems simply collapse... This is radio, and Dxers Unlimited is your 
radio hobby program amigos...
Now here is ASK ARNIE, the most popular section of the show..
Today answering a question about antennas... more specifically, a 
Canadian listener, Ian, from Nova Scotia wants to know what's the best 
antenna for monitoring TV meteor scatter signals...
Well amigo Ian, there are several antenna types you can install to pick 
up meteor scatter signals, but let me tell you about my two favorite 
ones : The 50 to 100 MegaHertz classic 10 element log periodic design 
with the forward V shaped
elements and a 200 ohms transmission line, can be redesigned to do dual 
service, by extending its frequency coverage to 150 megaHertz. This 
antenna design provides more than enough gain for TV meteor scatter 
work, and will also
prove to be a nice antenna for catching Sporadic E openings on the lower 
TV channels and the whole FM band, plus, if you are an amateur radio 
operator, it will also provide you with an antenna system for the SIX 
and TWO meter bands.
The 50 to 150 megaHertz log periodic is not a small antenna, and it does 
involve a lot of complicated mechanical work, but as many things in 
life, your efforts will be more than compensated by excellent results. 
Just recently I had the opportunity of seeing a very expensive 
commercial log periodic antenna
designed to operate from 40 megaHertz all the way up to 200 megaHertz, 
and my friends, what a surprise, the very well known antenna 
manufacturing company had designed the antenna using WIRE ELEMENTS, 
except for two of them, the reflector and the last director. This 
antenna was designed to be used for portable emergency communications, 
but there is no reason why it can not be duplicated for permanent 
station use.
The longest element of the LOW BAND TV CHANNELS PLUS FM BAND LOG 
PERIODIC,  is a little more than 3 meters long and the shortest element, 
is about 85 centimeters long.
The antenna is built using a sort of fiberglass canes crossbow, and two 
dacron lines that run from the reflector element to the last front 
active element. In between these two aluminum tubing elements, all the 
rest of the antenna's active elements are made of copper wire cable, 
covered with a teflon insulation.
YES... sure, it's a VERY EXPENSIVE professional commercial antenna, but 
it can certainly be duplicated at rather low cost by any person with 
average mechanical construction abilities.
So amigo Ian, that's in my opinion the best option for Meteor Scatter 
Dxing... and then there is a very low cost , much easier to implement 
one... The classic FAN DIPOLE PLUS reflector...using active elements of 
1.2 meters ... Four such elements and a reflector cut for a frequency 
five percent below 55 megaHertz is all that you will need to start 
picking up meteor scatter signals on an everyday basis, if you are 
fortunate to have channels 2 or 3 empty at your location.
Last but not least, a well known TV Dxer told me that he had a lot of 
success picking up both meteor scatter and sporadic E propagated signals 
using a pair of crossed dipole nests, with wire elements cut for half 
wave resonance at 55,
66, 77 and 88 megaHertz. Each of the dipoles placed at 90 degrees from 
each other go to a coaxial switch, and he told me that this antenna was 
very effective during sporadic E openings when placed just 10 feet or 
about 3 meters above his roof.
So amigo Ian, I hope that you are pleased with this reply to your 
question, and maybe, as the weather improves in your part of the world, 
you can start assembling one of these antennas and start looking for TV 
DX !!
My advice is to start by building the wire dipoles nest, feed it with 75 
ohm coaxial cable , and have them ready just before the Sporadic E 
season starts in late April or early May...

.....
This is the weekend edition of Dxers Unlimited coming to you from 
Havana, and here is item four: The very controversial broadband over the 
power lines, or powerlines communications systems , also known as BPL , 
continues to be developed, and now there are at least three systems that 
claim to be much more radio users friendly than the already existing 
ones. Among the recent upgrades to BPL systems are the availability of 
notch filters, that can reduce the signals radiated on specific segments 
of the HF spectrum in a significant way. For example, a Broadband over 
the Power Lines system recently tested proved to be much more compatible 
with amateur radio stations operating on the 80, 40, 30 and 20  meter 
bands, although the noise level on 160 meters was still so high as to 
turn that band useless in the area.
Another aspect of BPL that I haven't seen dealt with in a significantway 
is how amateur radio and other users of the HF spectrum will totally 
disrupt the Internet connections via Power Line Communications 
systems.... something to be expected considering the very little 
shielding that the BPL modems in plastic cases may provide...
BPL systems in Spain claim that they are operating with very little 
complaints from other users of the radio spectrum , but they have not 
produced either statistics or actual field strength measurements to 
prove their claims...
As a close neighbor of mine whose life depends on a sophisticated on 
demans pace maker device connected to his heart, told me recently, 
electromagnetic compatibility is becoming more and more a vitally 
important issue. My neighbor was specifically instructed by his 
physicians to stay away, as far as possible
from radio transmitting equipment that may disrupt the operation of the 
heart pacemaker... so every time he sees me around the block with my 2 
meter band FM handie talkie hanging from my belt, he sounds the alarm 
and tells me, " Coro, if they call you on the ham radio, move away from 
me before pressing the push
to talk button"... Reminiding me of the fact that BPL future users will 
not be able to do the same to safeguard their digital data streams in 
the presence of ham radio transmissions !!!
.......
More LINUX programs for amateur radio ... here are two
nice URL s... http://radio.linux.org.au
and http://www.qsl.net/dl9rdz
And yes, you can run LINUX directly from your CD Drive,
that is, you can actually boot a fully functional LINUX operating
system from your computer's CD Drive, without interfering
at all with the operating system on your main hard drive.
Tests I have done here recently with such self booting LINUX
distributions , have demonstrated that they are fully capable
of running software for operating PSK31 , the extremely
popular sound card keyboard to keyboard communications
mode... PUPPY LINUX most recent distribution works very
nicely , and another compact distribution known as DSL
or Damn Small Linux also gives very good results...
As LINUX becomes more and more user friendly, programs
for radio hobby applications are going to be much more common
than what they are today... and they all have a great advantage
over propietary software.... practically all of them are freeware !!!
......
Tips and techniques for the radio hobbyst... here are two for
today... Instead of buying expensive ceramic , polyethilene or
teflon antenna end insulators for wire antennas... use the highest
possible quality dacron sailboats ropes ... The dacron ropes
used by sailboat enthusiasts are extremely resistant from
a mechanical point of view, and will last a long time , even
when installed at places like very sunny Cuba where ultraviolet
radiation from the Sun reaches very high values. A 50 centimeter
or half a meter long length of dacron rope will be much more
effective at 30 megaHertz than a string of 3  egg type ceramic 
insulators or two polyethilene ribbed insulators, and as I already
explained will cost you much less...
This technique is specially useful when you need to install
a stealth antenna, because there will not be any insulators
to shine and denounce the existence of the skywire. If you
choose a blue or black dacron rope, and use blue of black
teflon insulated antenna wire... your stealth antenna will
go unnoticed for a long time,and as many of you city dwellers
know , antenna installation restrictions are becoming a really
big problem for radio hobby fans wanting to operate on the
HF bands...
And now as always at the end of the show  , here is our
HF plus low band VHF propagation update and forecast...Solar activity is 
now at a very low level, with the solar flux approaching the baseline at 
70 to 75 units. Geomagnetic activity will be settling down 
progressively. The effective sunspot number is 17 and early morning 
local time in Havana, at 13 hours UTC the A index had already gone down 
to 8 units. Expect a fast drop in the maximum useable frequency just 
after sunset, as solar cycle 23 continues its downward spin...
Send your signal reports and comments about this
program to arnie@xxxxxx, or VIA AIR MAIL to Arnie Coro
Radio Havana Cuba, Havana, Cuba... I appreciate them
very much amigos, and they sure help to make Dxers Unlimited
a better program !!
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