RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, JULY 3, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi amigos, welcome to the mid week edition of Dxers Unlimited, coming to you today via local phone link to the RHC studios. I am Arnie Coro, radio amateur CO2KK, the host of this twice weekly show, and here is our menu for today:
Item one: solar activity has switched to the very low mode, while not one but two very high latitude sunspot regions continue to puzzle scientists...Solar flux just barely above 130 units!!!
Item two: more about how to repair radios...
Item three: copper tape wound antenna is accepted by many as a piece of modern art decoration, and it works!
All this and more, right here on this same frequency you like to tune in to also pick up the most up to date HF plus 6 meters propagation update and forecast...
Jose Costa Pupo is my sound engineer and producer at RHC studio number 6... stay tuned for more radio hobby related information coming to you in just a few seconds...
Solar cycle number 23 continues to puzzle scientists, the latest stunt of this cycle was the appearance of not one but two sunspot regions at very high southern solar latitudes. According to long-time Cuban solar observer Angel Gonzales Coroas, his research showed that such high latitude sunspots are very rare indeed, and so far there is no explanation for them. Angel also told me that the first high latitude sunspot group disappeared by Monday, while the second one was still visible early Tuesday. At this moment my solar optical observations and his coincide, in that there is no sunspot group showing signs of complex magnetic activity, something that will translate into a rather quiet geomagnetic field during the next three days or even more...
Item two: Lots of radio equipment is available at reduced prices or even just for the asking, due to it not been operational... BUT, is it worthwhile to buy or even just to transport a broken down radio?
My to that question is always YES.... ABSOLUTELY, as patience, know-how and standard workshop repair procedures can many times bring a radio back to life.... Here is a good example...
Francisco, my across La Torre street neighbor, gave me a dead Russian VEF 206 receiver, also known as a VEGA 206, a 10 transistor radio that covers Long Waves, Medium Waves and several bandspread short wave bands. It took about three days of hard work to bring the dead VEF 206 back to like new operating parameters.... and this was fun! Because the technicians at the neighborhood radio and TV repair shop had told Francisco that the set was beyond repair... Among the things I had to do were taking the radio apart from its cabinet, brushing, cleaning and air blasting it, and then very carefully inspecting the circuit board, where I found several transistors that had their connecting leads broken due to corrosion.... I had to replace 5 of the 10 transistors with new ones, change three electrolytic capacitors and completely realign the set....
BUT, it was surely worth the effort, as the receiver is now working even better than when new... Hard to believe? Well here is the answer: I replaced the damaged transistors with much better new ones... so the radio's sensitivity improved tremendously, as well as the audio quality. And this is only an example of how you can bring back to life some nice radios that other people may have simple thrown to the dump.
In another example, this one a much more expensive and complex amateur radio transceiver, just replacing a lithium battery and two burned-out output transistors brought it back into service... The previous owner had decided, after consulting with several self proclaimed experts, that the radio's mainboard was damaged beyond repair...
And what had really happened is that two problems had added together to make the transceiver non-operational... without the lithium battery, the transceiver's basic microprocessor control unit was without power, and that caused a blank frequency display... See amigos, summer hamfests and garage sales are a good opportunity to obtain several more radios for your collection, or to pass them along to friends who are just starting to enjoy our wonderful hobby!!!
You are listening to the mid-week edition of Dxers Unlimited coming to you from Havana... A nice ART-ANTENNA, made with a length of white PVC drain pipe and spiral wound copper tape...
It is attached to wooden base and looks really nice, so nice-looking it is that my wife Olga accepts it as part of our entertainment room decoration... And this new ART-ANTENNA version of my now famous BROOMSTICK has proven to be ideal during this year's above-average thunderstorm season... With the ART-STICK I can keep on listening to short wave stations with my battery powered receiver even when the thunderstorms are in the area, something I wouldn't dare to do with an external antenna connected... The ART-STICK is about 2 meters high, and looks, as I said, like a modern art decoration object...
The copper tape spiral shines nicely! The ART-STICK is still in the prototype stage, and as soon as I have it ready, you will be able to learn more about it... It is an easy-to-homebrew antenna, and when connected to a carefully disguised ground radial, it proved to work on the 20 meter amateur band so nicely that I was able to make a two-way CW contact with an amateur in the US using just 5 watts and the indoor ART-STICK....
If you want to know more about the ART-STICK antenna right now, just send me an e-mail to arnie@radiohc.org and I will send you a text file describing it, but you must wait for the drawings and photos, as I still have to make them!!!
Anyway, the ART-STICK proves my point that ART and TECHNOLOGY can work together to produce a reasonable efficient antenna at low cost that will also be appreciated as a nice art object too!!!
You are listening to the mid-week edition of Dxers Unlimited, and if you notice a restricted audio bandwidth, the reason is that I had to tape the show, not at our studio, but from my home QTH today.
Now here is item four: The very popular you have questions and Arnie answers them... this question sent in by a listener in the Netherlands:
Arnie, have heard you talking a lot about the regenerative receivers and the many ways that they can be built using vacuum tubes or solid state devices... My question is the following: Is there any specific circuit that is of your particular preference... In other words, is there a high performance regenerative receiver of your choice??
Well amigo from the Nederlands... the answer is not an easy one, as it will depend on the application... For example, if you happen to have access to high quality brand new RF pentode receiving type vacuum tubes, then you can build yourself a very high performance regenerative receiver with a very smooth regeneration control...
And if you decide to use my REGENERODYNE design, then your radio will be a really top performing set.... BUT, I do warn you, many of those who have built regenerative radios in the past have not obtained very good results due to a number of good reasons, among them the lack of a really good design and detailed clear easy-to-understand, step-by-step building instructions... as regeneratives are in a certain way tricky circuits that do require experimentation...
If you build your first regenerative and it doesn't work properly, chances are that you won't build the second one.... and that's why many people just drop this circuit and go ahead to build a more complex super-heterodyne or a simpler direct conversion set...
Solid state versions of the most popular regenerative receivers are not so easy to find, but there are at least two, one by my good friend Paul Harden NA5N, and another by Charles Kitchin that work really well as short wave receivers for beginners and experts... Paul's circuit is known as the Desert Rat, and Charlie Kitchin's radio has received very favorable reviews is prestigious amateur radio magazines the world over... Maybe soon you will be able to read a lengthy article about the Hollow State Regenerodyne that I have almost finished here now...
This is Radio Havana Cuba... don't forget to try to pick up our Single Side Band energy efficient transmissions on the following short wave frequencies... 13660 kiloHertz, 11705 kiloHertz and 9830 kiloHertz.... Upper side band....
Here is now Dxers Unlimited's item five: Another answer to another question: Yes amigo, OPTO COUPLERS do provide good high frequency response if you happen to choose the right one... and YES, there are at least two receivers that use OPTO COUPLERS to improve isolation between the antenna and the input tuned circuit... one of them is precisely an OPTICALLY COUPLED REGENERATIVE RECEIVER, that offers, according to its designer, a very smooth regeneration control....
And now amigos, as always at the end of the show, here is Arnie Coro's HF plus 6 meters propagation update and forecast... Solar activity was very low on Monday, and the optical observations done here in Havana and in Camaguey show that the sunspot groups are very small and without any complex magnetic activity... So, you may have to change your forecast for the next week or so, if no new active sunspot regions come on stream.
Nighttime maximum useable frequencies continue to show a very nice enhancement, so follow my advice and operate your radios mostly after local sunset, and if you want to work some nice DX, then stay awake until well past midnight...
See you at the weekend edition of the show amigos, and remember to send me your signal reports, comments about the show and radio hobby related questions to arnie@radiohc.org and via AIR MAIL to Arnie Coro Radio Havana Cuba, Havana, Cuba.
Arnie Coro CO2KK
Havana, Cuba
July 3, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
To Arnie Coro's Dxers Unlimited
Back to NY Transfer's RHC main page