Radio Habana Cuba: Dxers Unlimited mid-week edition for March 20, 2001
By Arnie Coro, radio amateur CO2KK
Hi amigos, you are listening to the mid-week edition of your favorite, listener oriented radio hobby show... This is the spring equinox special! Yes, we are right there, the Sun is exactly crossing over the Equator, so the Earth's two hemispheres are getting almost equal illumination, something that produces some very interesting HF propagation phenomena... Among them, an enhancement of the ionosphere, which sometimes can send back to Earth radio waves on frequencies as high as 50 megaHertz, just as it happened last Sunday, when 6 meter band operators enjoyed one of those unique equinoctial trans-equatorial DX season openings that will be remembered got a long time.... Imagine that Argentine 50 megaHertz band operators had pileups that sounded like a 20 meter band DX expedition, and that in the middle of a pileup of North American stations, I suddenly hear an LU, an Argentinian amateur calling an ECHO HOTEL SIX, yes! He was calling a station, another 6 meter enthusiast, who was located in the Balearic Islands... Minutes later I heard him also working an ECHO HOTEL SEVEN, located in Spanish continental territory...
Sorry for me, I could only hear the South American station... But, nevertheless this was quite an interesting Sunday afternoon here, especially if you think that I had my 6 meter transceiver on since local noon, waiting for the expected opening to happen... Yes amigos, mes amis, my friends, operating on the 6 and 10 meter amateur bands is a very rewarding experience indeed!!!
Item two: Seems like the REGENERODYNE receiver design which I have promoted here for the past several months is picking up more and more homebrewer's interest... Now I see that a recent article in one of the US amateur radio magazines shows how to build a receiver for short wave listening that uses the REGENERODYNE principle of operation, with the regenerative detector working at 455 kiloHertz... It is a double conversion receiver, but it has, in my humble opinion, one great design flaw... it relies on the stability of the variable high frequency oscillator, something that in the past has proven to be not a good idea, especially with receivers built by hobbyists who are just starting to homebrew their radio equipment... More about the Optically Coupled OCR II receiver later in today's equinoctial day edition of Dxers Unlimited, your favorite radio hobby program, now coming to you with a full 18 minutes of all radio hobby-related items.
Margarita Delgado is my sound engineer and producer, I am Arnie Coro in Havana back with you in a few seconds, after a brief musical interval...
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and our fast response, interactive e-mail address is very easy to remember amigos ... send mail to arnie@radiohc.org and if you aren't yet in cyberspace, use Air Mail to send your signal reports and comments about the show... to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Now item two in detail... A solid state version of the REGENERODYNE, under the name of OCR II appeared last year in one of the leading US amateur radio journals... The design uses a very clever way of coupling, or should I say, decoupling, the regenerative detector from the rest of the circuit, by means of an OPTO COUPLER, a unique hybrid optoelectronic device that isolates circuit elements, by changing, in this case, the radio waves to light waves, and then back to radio waves, forming a sort of light barrier that is very useful to isolate one part of an electronic circuit from the other.
The OCR II Regenerodyne receiver was not presented as such; the author just called it the OCR II, without explaining to the readers that he was actually using the Regenerodyne system, that is, a front end working into a regenerative detector... One disadvantage of the OCR II is that it relies on the stability of the front end's variable frequency oscillator, and keeps the regenerative detector operating at a fixed frequency of 455 kiloHertz, something that was obviously done because of the availability of commercially made intermediate frequency transformers for that popular IF.
As many of you know, after listening to the several programs devoted to the Regenerodyne receivers, the best approach for designers of those radios, is to use a crystal-controlled front end and a variable tuning regenerative detector circuit, something that provides much better stability... Maybe I'll try the OCR optically coupled receiver design, using a crystal controlled front end, working into an OCR couple regenerative stage operating between 2 and 4 megaHertz.... Sure, it should be a pretty nice arrangement indeed.... Maybe you will want to try it too!!!
By the way, if you have already build a REGENERODYNE, send me an e-mail or a postcard, telling about how it works.... seems like everyone who has built one has obtained outstanding results, something that leads to the possibility of designing a kit using the REGENERODYNE design... This could probably be produced at much lower cost than a conventional superheterodyne receiver kit, and its performance will be much better than the now-popular regenerative short wave receiver kits that are available from several radio kits suppliers. Your opinion on this subject will certainly be appreciated, too, amigos!!!
This is Dxers Unlimited, and we are now on our new 18 minute format,,, YES, 18 minutes, full of all radio hobby-related information amigos!!! Here is item three: HF propagation disturbance in progress right now, the A index went up to 19 on Monday, and early morning local time Tuesday, when I was writing this script, at around 12 hours UTC, the three hourly K index was as high as 6, which will almost surely generate AURORA BOREALIS at even middle latitudes. Probably those of you located at or above 40 degrees North will feel the effects of the geomagnetic storming....
Item four: QSL on the air, QSL on the air to my good friend Erik Koei, who also is one of those listeners who stay up late in Europe, or use a timer and tape recorder to pick up our 6000 kiloHertz frequency beamed to North America East, but heard well in Europe from around 00 to 02 and sometimes even to 03 UTC.... Amigo Erik, thanks for the nice report, and SURE, you will be getting our SPECIAL 40th Anniversary QSL card!!! By the way, Erik's report shows a SINPO of 4443 and the last digit variable between 3 and 4... and he received Dxers Unlimited's at 0135 to 0200 UTC on March 18th, that is our past weekend edition. QSL on the air to the many Dxers Unlimited's listeners who have requested the Regenerative and Regenerodyne receivers info package.... I must admit that there is a little delay sending them, and now I am thinking about zipping those files into a single.exe file that will unzip automatically to make things easier for yours truly, as it is quite a chore to select file by file and add them as attachments to the e-mail message...
Again, I have a wonderful collection of circuit diagrams for both solid state and vacuum tube regeneratives and regenerodynes, that you can request by sending an e-mail to arnie@rhc.cu, again, very easy to remember, arnie@radiohc.org or via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba, no need for PO BOX number as the Havana's main post office mail sorting system employees know me and the station very well, indeed....
So, if you want to take a look at a collection of some very interesting radio receiver circuits that spans from the early nineteen thirties until the end of the 20th Century just drop me an e-mail or send an AIR MAIL postcard... and do remember to include in the text that you want to receive the Regenerative and Regenerodynes Receivers Diagrams Collection...
Now here is item five: More about the KK4 skeleton J antenna, following the construction of a second prototype by Carlos CO2FU this past weekend. Monday I was operating on the two meter band, FM mode, talking on a simplex frequency with my elder son Arnie Jr. CM2KW... when I was almost ending the QSO, CO2FU, Carlos gave us a call, to test a new antenna that he had just completed... Well, it was the number two prototype of my KK4 Skeleton J antenna, which he had completed during the weekend and, according to what he told us, was to be kept ready, as a standby portable antenna for emergencies... Carlos also told Arnie Jr, who is an enthusiastic antenna builder, that this second prototype used copper wire of a smaller diameter than the first one, but that despite that change, the antenna was giving a perfect one-to-one match to the 50 ohm coaxial cable... He also explained that he had just soldered the coaxial cable to the feedpoint at the same distance from the bottom of the antenna as he had found experimentally for the first one, that is 9.5 centimeters, and that this did not require any further adjustment. CO2FU's signal on the second prototype of his homebrew KK-4 skeleton J was a solid S9, even when running his handie-talkie at the low power setting.
We then moved to the long range repeater frequency, on 145.110. and proceeded to test how CO2FU's signal was heard by the mountaintop repeater... something that proved to be very rewarding, as the signal was loud and clear, even at the low power setting... For those of you who have not heard about the KK4 skeleton J antenna, this is a very easy-to-build, very low-cost antenna for the 2 meter FM band operators that will boost the signal by no less than between 6 and 8 decibels when compared with the handie-talkies' standard rubber duck antenna... The KK-4 is made using a 2-meter long length of PVC pipe, some 4 meters of copper wire, a length of 50 ohm coaxial cable and a coaxial connector that will fit your hand held FM transceiver. AND YES, as usual here, the complete diagram in .jpg format and the step-by-step building instructions are available for free. Just send an e-mail to arnie@rhc.cu and specify that you want to receive the KK-4 antenna file. This is a nice weekend project.... and you will save a lot of money too, as this one is a lot cheaper than any equivalent commercial antenna!
And now, just before going QRT here is Arnie Coro's exclusive and not copyrighted HF propagation update and forecast... Geomagnetic storming should be in progress at the time you hear this program, and it will probably continue intermmitently for the next two to three days... Solar activity will very problably NOSE DIVE down to the lowest level in many months after the two active sunspot regions that are now near the SUN's limb turn around out of sight. So, AM medium wave band and Tropical Band Dxers may have quite a few days of remarkable equinoctial Dxing, as ionospheric absorption will reach bottom low levels when the solar activity goes to the very low values expected, starting in around two days from now. Six meter operators should continue to be on the alert, as any sudden flare activity from the one potentially active sunspot region could produce worldwide openings on that band...
See you all at the weekend edition of Dxers Unlimited, next Saturday and Sunday UTC, and for those of you who are already amateur radio operators, it would be nice if we can have a two-way QSO on 10 meters... This past weekend I enjoyed a lot talking to many Dxers Unlimited's fans who are also ham radio operators... Remember to monitor 28.500, 28.5 for CO2KK. See you there, amigos!!!
prepared 20-Mar-2001; transmitted 21-Mar-2001 14:58 EST
Arnie Coro CO2KK
Havana, Cuba
March 20, 2001 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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