Re: [HCDX] Dxers Unlimited mid week edition for 13-14 November 2007

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

NOTE: This program features re-runs about solar cycle predictions
about DRM ,and details about the G5RV as compared to the Fan Dipole,as 
was requested by many listeners.

Radio Habana Cuba
Dxers Unlimited
Dxers Unlimited's midweek edition for Nov 13-14 2007
By Arnie Coro
radio amateur CO2KK

Hi amigos radioaficionados... from Havana, this is the midweek edition 
of your favorite radio hobby program the one and only featuring the most 
up to date HF plus low band VHF propagation updates and forecasts... I 
am Arnie Coro, radio amateur CO2KK, your host here at Dxers Unlimited, a 
show devoted to the promotion and development of our wonderful hobby, 
yours and mine ... RADIO... Item one: Scientists now are voicing their 
different opinions about the forecasts that upcoming solar cycle 24 will 
be the one reaching the lowest peak number of sunspots in many, many 
years... as a matter of fact, the peak mean sunspot number expected, and 
this, I emphasize is according to one school of thought is said to be 
barely 75 mean sunspots, something that will turn the frequency range 
above 20 megaHertz into the equivalent of a VHF band for years to 
come!!!... So, if we believe this forecast it’s about time to prepare 
for much lower solar activity to last for a loooong time amigos!!! The 
other group of solar scientists says that cycle 24 may be very active, 
and even so active as to reach an average sunspot number that will get 
close to the record breaking cycle 19, the one that passed the 200 
sunspot number mark Item two: Uncoordinated DRM, digital radio mondiale 
broadcasts are continuing to  harm reception of regular , standard, AM 
double side band plus full carrier, A3 mode international shortwave 
broadcasts, inside the bands assigned by the ITU for that service...The 
reason has nothing to do with DRM broadcast technology at all, the main 
causes of this problem can be traced to not coordinating properly so as 
to make DRM transmissions compatible with standard AM and also because 
of poorly adjusted transmitters used for some DRM broadcasts that are to 
be blamed according to experts Several highly qualified radio 
broadcasting engineers think that there is no room for DRM on the 
present high frequency international broadcast bands due to what they 
describe as an unforethought incompatibility between AM and DRM..., in 
other words, they are appealing creating special frequency spectrum 
allocations for DRM transmissions, so that they will not interfere with 
the traditional technology used by short wave broadcasters since the 
very early days or radio. This criteria  started when  several chief 
engineers at stations suffering from interference from DRM transmissions 
asked for those DRM broadcasts to be placed on a separate  segment of 
the assigned bands , effectively giving them a sub-band, something that 
in my opinion may prove to be a very wise move. In the meantime DRM, 
digital radio mondiale continues to be heard by only a very small number 
of listeners worldwide, as low cost, practical receivers for DRM are 
still practically non existent for the public to buy...
Once again your valuable comments about DRM broadcasts are invited 
amigos, just take a little time to send me your opinion about DRM to 
arnie@xxxxxx, or via air mail, send a postcard to Arnie Coro, Radio 
Havana Cuba, and Havana, Cuba...
Now stay tuned, for more radio hobby related information coming to you 
from Havana... I'll be back in a moment, after a short break...
......
More nice worldwide radio amateur contests will take place during 
upcoming weekends... In the case of these contests, what the winners 
will achieve is working the greatest number of stations, and each new 
country worked are the multipliers of the contest...!!! Operating during 
amateur radio contests is always a challenge and is one of the more than 
80 ways that you and I may enjoy this wonderful hobby...
Item four: More ham radio software available free of charge... at 
absolutely no cost, thanks to ham operators that make their programs 
freely available for the benefit of radio amateurs worldwide... among 
them the excellent propagation forecasting and now casting program by 
W6EL, by Sheldon C. Shallon, who wrote it in 2001 and then very kindly 
made it freeware.... I have used the W6EL propagation forecasting 
program for the last four years with excellent results, and it compares 
extremely well with professional, and I must add pretty expensive, 
software used for precise calculations of short wave radio 
communications. W6EL's program is very easy to use, and works on many 
operating systems, but so far I have not seen a LINUX version for it... 
In case you don't find W6EL's propagation software on the INTERNET's 
world wide web for downloading, just send me an e-mail and I will be 
very happy to send the dot zip file to you, as it is, believe it or not 
less than half a megabyte in size...There are also some very nice new 
ham radio software programs written to use the LINUX free and open 
source operating systems... Among them FLDIGI, that offers several 
digital communications modes, including the rather new OLIVIA and also 
the classic RTTY as well as the very popular PSK31.
Send your request to arnie@xxxxxx amigos, and sorry, there is no 
practical way for me at this moment to send this software by other means 
than as e-mail attachment amigos...
Item five at this midweek edition of Dxers Unlimited...it's the antenna 
topics section, an answer to a problem that a Cuban radio amateur was 
having  with his G5RV antenna for the 80 to 10 meter bands... He called 
  me on one of our local 2  meters band FM repeaters to say that he was 
having problems with this G5RV antenna..., his rig was oscillating badly 
when connected to the G5RV multiband antenna, and we soon found out that 
his antenna tuner's capacitors were arcing between the rotor and stator 
plates. The problem only happened on 40 meters, and the automatic power 
shutdown of his recycled Yaesu FT80 will then trip very often in the 
middle of a QSO... After reviewing the setup at his station, I 
recomended that he changed the length of the open wire line feeding the 
G5RV antenna, and also that on 40 meters he used a one to one balanced 
to unbalanced antenna transformer instead of the four to one ratio he 
was using... It seems like the impedance transformation done by the open 
wire line was making the antenna tuner's job a very difficult one... 
Once he changed the balun, the problem just vannished. The interesting 
thing about this problem is that he could work on 80, 20, 15 and 10 
meters without any problem, and it was only when he attempted to operate 
on the 40 meter band that the problem knocked his station off the air... 
I thought it would be a good idea to pass this along to Dxers 
Unlimited's listeners that are also amateur radio operators, because the 
G5RV compromise wire multiband antenna is very popular , despite the 
fact that it may act up on some bands as you have just heard. By the 
way, I have never installed a G5RV, because  a fan type wire dipole, fed 
with 400 ohms open wire length and with its legs between 11 and 25 
meters long is a much better antenna by all standards... Just remember 
to use three wires for each leg of the antenna and separate them at the 
end by about thirty percent of their length... For example, one of my 
favorite compact fan dipoles uses 7 meters long legs, separated by about 
2.3 meters, providing the user with an antenna that works very nicely 
from 40 to 10 meters ... A longer version about twice that size provides 
not only coverage of 80 meters, but also some gain on the higher 
bands... The separation between the upper and lower wires of the 14 
meters long fan dipole is 4.6 meters, but let me add that this is not 
really critical, as I have used this fan dipoles with less separation 
between the wires with very nice results... If you want to go by the 
book, the ideal length for these two antennas are 6.7 meters for the 
short version designed to work between 7 and 29.7 megaHertz and 13.4 
meters for the version designed to work between 3.5 and 29.7 
megaHertz.... The use 400 ohm impedance open wire line is essential to 
obtain the benefits of these antenna designs, and the actual length of 
the open wire line should be a bit more of a quarter wavelength at the 
lowest operating frequency , taking into consideration the velocity 
factor of the line, in this case about 0.92...  By the way, as an 
additional bonus, the fan dipoles are really broadband antennas, so they 
are excellent for monitoring purposes and listening to international 
short wave broadcasts from 6 all the way up to 26 megaHertz, that is 
from the 49 to the 11 meters bands..
.....
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, I am 
Arnie Coro, your host here at this twice weekly program devoted to all 
the different aspects of the radio hobby, from home radioastronomy to 
Dxing on the AM broadcast band with a crystal set... from working an 
amateur radio contest to wiring up your own low power QRP transmitter 
and using it on the air, accepting the challenge of operating with 
powers less than 5 Watts into the antenna... Yes my friends, radio is 
never boring, because you can always learn about a new and fascinating 
way of enjoying it ...Even at the solar minimum some very special 
propagation conditions dos how up...  At CO2KK my ham radio station I am 
picking up amateurs from South America on the 10 meters band practically 
every day, despite the extremely low solar activity and those are 
amazing signals considering the low powers used... Even with a simple 
half wave wire dipole just 3 meters above my rooftop, I have made 
excellent two way contacts on the 28 to 29.7 megahertz band,10 meters, 
with stations in Argentina, Uruguay, Brazil, Paraguay and Chile.
...
You have QUESTIONS, and Arnie tries to answer them as soon as they 
arrive here to my e-mail box arnie@xxxxxx, or at the postal address 
Arnie Coro, Radio Havana Cuba, Havana, Cuba... Today's question came 
from Germany, where many listeners pick up our English language web cast 
that goes on the air from 05 to 07 hours UTC... Amigo Dieter from 
Cologne asks if it is possible to use a retired C band satellite dish 
antenna for amateur radio work... Answer, sure amigo, you can turn that 
parabolic reflector into a useful antenna for both terrestrial and space 
Dxing depending on the type of mount that you decide to use. For 
terrestrial applications the typical 3 meters diameter C band retired 
satellite antenna will make an excellent reflector for amateur radio 
bands in the range between 70 centimeters and 5 centimeters... but as I 
just said, it will require a rather expensive mounting system so that 
the dish can be installed at enough height above ground and also rotated 
in azimuth... Some amateurs that live at hilltop or mountaintop 
locations have used the C band antennas at ground level, and aiming them 
by hand with excellent results, but not everyone has the privilege of 
enjoying such excellent " made for VHF, UHF and Microwaves " 
locations...By the way, once I placed a two meters band half wave dipole 
at the focus of a 3 meters diameter parabolic reflectors that was 
retired from satellite receive only duty and found out that it showed 
gain similar to a three element Yagi that was installed at the same 
height !!!
Now our exclusive and not copyrighted HF plus low band VHF propagation 
forecast... Solar activity is still at extremely low levels, zero 
sunspots one day after the other, and now expect a geomagnetic 
disturbance to make HF propagation at high latitudes still worse. The 
daily solar flux barely reaching 70 units.
See you all at the upcoming weekend edition of the program amigos, and 
don't forget to take a little time now to drop me an e-mail with a 
signal report and your comments about today's Dxers Unlimited, send mail 
to arnie@xxxxxx !!! Or Send an AIR MAIL Postcard to Arnie Coro, Radio 
Havana Cuba, Havana Cuba.


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