Re: [HCDX] Dxers Unlimited's weekend edition for 1-2 September 2007

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

Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s weekend edition 1-2 September 2007
By Arnie Coro
Radio amateur CO2KK

Hi amigos radioaficionados… I am Arnie Coro , radio amateur CO2KK in 
Havana, inviting you to stay here on this frequency or world wide web 
connection listening to Dxers Unlimited’s weekend edition… Well, here we 
are, now right at the start of the autumn equinoctial DX propagation 
season, as I like to properly call it… Because there is no doubt that no 
matter how the solar cycle is behaving as the autumn equinox approaches 
short wave propagation conditions around the world improve dramatically 
for a period that usually lasts from four to six weeks… starting just 
now, when during the first week of September one starts to notice how 
the HF bands begin to improve…
For example 20 meters, the queen of radio amateur DX bands will be open 
to one part of the world or another for many more hours every day… 
Wednesday afternoon I heard a very loud signal on 20 meters single side 
band coming from the United Kingdom into the Caribbean… The UK station 
was benefitting from the typical local sunset propagation enhancement, 
and he was an S 9 plus 10 dB on peaks perfect copy on my 20 meters band 
half wave dipole “slopper” antenna, that is tilted at a 45 degrees angle 
with the lower end aiming at Europe, to make one of the lowest cost 
“beam antennas” that you can imagine…
So amigos, follow your friend’s Arnie Coro advice and devote more time, 
from now on to operating your radios, because propagation conditions 
will continue to get better and better for the next three to five weeks…
Stay tuned because after a short break for station ID, Dxers Unlimited’s 
weekend edition will continue in afew seconds… I am Arnie Coro in Havana…

…….

The name of the station is Radio Havana Cuba, we have been on the air 
since 1961, and we are proud of providing our listeners with one of the 
world’s best QSL services… Yes , we do verify reception reports with a 
nice , beautiful QSL CARD… a collectors item by all standards amigos… 
Send your signal reports, comments about our programs and radio hobby 
related questions to arnie@xxxxxx or VIA AIR MAIL to Arnie Coro, Radio 
Havana Cuba, Havana, Cuba…
And now here is item two, also HF propagation related… Tropical Bands 
propagation also benefits from the autumn equinox season, and this is 
your opportunity of logging some nice catches on the 60 meters Tropical 
Broadcast Band, the one that still has a relatively large number of 
stations on the air… Let’s start with our own Radio Rebelde, from Havana 
operating 24 hours a day on 5025 kiloHertz for our domestic near 
vertical incidence skywave coverage of the Cuban archipelago, something 
that the Tropical band is able to do with just one transmitter and a 
special NVIS antenna system… But, the NVIS antennas also have minor 
lower take off angle lobes that send the signals at much longer 
distances, and that’s why you can pick up Tropical Band domestic 
services from across the globe… Here are a few stations from Africa that 
may be logged in North America and Europe during the present autumn 
equinoctal DX season… Starting with ANGOLA.on 4950 , from Mulenvos, but 
beware that this transmitter is usually with very low modulation index.. 
 From the Republic of Benin, on almost exactly the same frequency as 
Radio Rebelde on 5025 kiloHerts is Radio Parakou, that you may catch 
when late in the evening daylight saving time, around 0500 UTC Radio 
Rebelde’s 50 kiloWatt transmitter on 5025 kiloHertz is off the air for 
routine maintenance…something that happens about once a month… at other 
times picking up Benin of 5025 kiloHertz is a matter of luck, when 
propagation changes in favor of the African station over the Cuban on 
the same channel.
Moving just 5 kiloHertz up the 60 meters Tropical Band from 5025 to 5030 
kiloHertz you may sometimes pick up BURKINA FASO,’s Radio Burkina from 
the capital of that African nation Ougadougou, again when a the station 
from Costa Rica on the same frequency is not on the air, or propagation 
at your location favors the African continent..
These are just four examples of Tropical Band stations that you add to 
your logbook during the present equinoctial DX season amigos, but there 
are many, many others that make very interesting listening ,especially 
for the nice music they play that you will very rarely if ever hear at 
your local FM one hundred thousand watts stereo powerhouse !!!
….

Now amigos, here is our technical topics section, that will be devoted 
today about the growing interest among radio amateurs to use AM 
modulation, and by that I mean standard double side band plus full 
carrier AM, the first way of superimposing voice and music on a radio 
carrier wave… A few days ago during a 40 meters bandscan that I was 
doing late at night with my REGENERODYNE homebrew receiver set for 
picking up CW and Single Side Band station, a loud signal produced a 
really loud heterodyne… backing off the regeneration control, the AM 
signal came in with excellent audio quality. It was a radio amateur from 
Ohio, USA, operating a vintage transmitter that he described as more 
than 50 years old. The four dash four hundred tetrode final , modulated 
by a pair of eight thirteen tetrodes was certainly providing excellent 
reception. The proud owner of the AM rig was using a simple half wave 
dipole , so his actual antenna gain was zero db or decibels over a dipole.
He told the stations he was talking to that he was using a 1950’s 
vintage Viking One transmitter at a very low power setting to drive the 
big tetrode that was fed with three thousand  volts on the anode… The 
classic class B modulator with the eight thirteen tetrodes provided all 
the audio needed for one hundred percent modulation and more, something 
that as he properly explained is very important if you want your AM 
signal to provide the highest possible quality sound with very low 
distortion… But this Ohio ham operator was not the only one I have heard 
recently, because as I just said more and more radio amateurs are coming 
back to AM to enjoy the beautiful audio quality that is possible using 
that form of modulation, while at the same time keeping on the air some 
nice antique equipment…. I have heard recently AM amateur stations also 
on 20, 15 and 10 meters, and the hams operating those stations seem to 
enjoy it a lot, as they are not chasing DX or working one station after 
the other in contest… they are just relaxing , talking to each other and 
discussing some very interesting technical topics, like the design and 
construction of amateur radio transmitters that use amplitude modulation 
techniques, not only the classical ones everybody knows about, but some 
of the more advanced pulse width modulation technology that has become 
almost a defacto standard for AM broadcast stations but that has seen so 
far very little if any use among the world’s radio amateurs.

……
You are listening to the weekend edition of Dxers Unlimited coming to 
you from Havana, and here is now LA NUMERO UNO, the number one most 
popular section of the show…
YOU have questions and your amigo Arnie tries to answer them… Here is 
today’s question sent by listener Gabriel from Atlanta, Georgia , USA… 
Gabe, as he signs his e-mail, wants to know more about regenerative 
receivers and why they seem to have such a devoted group of people 
around the world always experimenting with those circuits that , he very 
well describes them, do require a lot of attention to construction 
details in order to achieve good performance… Well amigo Gabe, it may be 
a matter of accepting a challenge, or the pride to be listening to a 
relatively simple radio that you have built yourself, and that picks up 
distant stations better than your store bought radio… Maybe those are 
the main reasons that make radio hobby enthusiasts enjoy so much 
discussing the circuits with friends at the e-mail lists devoted to 
regenerative receivers, changing parts values to see how the performance 
of the radios change, or experiment with rarely known circuits used in 
the very early days of radio and long forgotten, like the so called 
“space charge tetrodes ”, that became popular because it made possible 
to build a radio receiver that used only one single 6 , 9 or 12 volts 
battery…. And this of course was happening when radios were battery 
operated and required expensive so called B PLUS   B+ batteries for 
providing the high voltage to the vacuum tubes anodes… Just for your 
information amigo Gabe, I have sent to you already , via e-mail the 
circuit diagram and my notes of a regenerative receiver that uses low 
voltage for feeding the anodes or plates of the vacuum tubes, in other 
words, it doesn’t require the use of a high voltage power suppy, because 
both the tubes filaments and anodes are fed from the same 12 volts DC 
power supply… Maybe you can homebrew this receiver diagram that has 
given many radio enthusiasts many hours of nice AM broadcast band and 
shortwave listening…
Please note amigo Gabe that the vacuum tubes types used are not critical 
at all, so you won’t need to spend a lot of money buying specific tube 
types that are much sought  by HI FI audio hobbysts who are erroneously 
led to believe that certain tube types have some magical qualities that 
make their audio sound better than others… My prototype of this cascode 
regenerative 12 volts operated set was built and is still operating 
using vacuum tubes recycled from TV sets that were retired from service… 
I never even tested those tubes , just plugged them in, and the radio 
started to provide excellent reception , so I just left them there amigo !!!
Now for those of you wanting to learn more about regenerative receiver 
circuits, both vacuum tubes and solid state, just send me an e-mail to 
arnie@xxxxxx, and I will send you a few circuit diagrams plus the 
address of one of the most popular regenerative receivers discussion 
forums on the Internet, that I strongly recommend you to join, as it is 
a treasure chest of knowledge that its members share with each other in 
a most civilized and educated way, with a spirit to share what each one 
knows that is an excellent example of how the Internet can be used for 
the promotion and development of the radio hobby …
And now as always at the end of the show, here is Arnie Coro’s Dxers 
Unlimited, HF plus low band VHF propagation update and forecast.. Solar 
flux still at very low levels and a new sunspot group is growing, but it 
would not produce big solar flares according to what can be seen. The 
equinoctial propagation conditions are now very much in progress , so if 
the flux increases above 80 units we are going to see much better 
propagation by mid September… See you all at the mid week edition of 
Dxers Unlimited, next Tuesday and Wednesday UTC days amigos !!!




---[Start Commercial]---------------------

Preorder your WRTH 2007:
http://www.hard-core-dx.com/redirect2.php?id=wrth2007
---[End Commercial]-----------------------
________________________________________
Hard-Core-DX mailing list
Hard-Core-DX@xxxxxxxxxxxxxxxx
http://montreal.kotalampi.com/mailman/listinfo/hard-core-dx
http://www.hard-core-dx.com/
_______________________________________________

THE INFORMATION IN THIS ARTICLE IS FREE. It may be copied, distributed
and/or modified under the conditions set down in the Design Science License
published by Michael Stutz at 
http://www.gnu.org/licenses/dsl.html