Radio Habana Cuba: Dxers Unlimited weekend edition for March 10, 2001
By Arnie Coro, radio amateur CO2KK
Hi, amigos! Welcome to the weekend edition of Dxers Unlimited! I am Arnie Coro, radio amateur CO2KK, your friend here in Havana and host of this-twice weekly show which is coming to you via shortwave and with scripts also available for reading on the worldwide web!
Here is item one.... A burst of solar activity concentrated near solar active region 9368 has produced several M class solar flares during the Friday and Saturday UTC days...
Item two: Spring equinoctial DX season is obviously in full swing... Easter Island Dx station is heard on 6 meters at many locations worldwide...
Item three: Dxers Unlimited's listeners are homebrewing a lot of radio gear, mostly receivers, antenna tuners and antennas... a few tips about how to find more electronic components for your homebrew projects later in today's weekend edition of your favorite, listener-oriented, technically minded, radio hobby show...
Item four: High Q coils are essential for the high performance crystal radio receivers... more about how to achieve high Q also here today...
Stay tuned for more all radio hobby-related information right on this same frequency... Margarita Delgado is my sound engineer and producer at Radio Havana Cuba's studio number 7... I am Arnie Coro, back with you in a few seconds amigos....
Homebrewing radio gear is a lot of fun.... simple weekend projects like a power supply to replace your radio's batteries, an antenna tuner to improve your cross modulation problems on that small portable receiver, or a simple test instrument that will provide an easy way of knowing when there is circuit continuity are among the most popular projects that Dxers Unlimited's listeners tell me that they build. Somewhat more complex projects like short wave receivers take more time to build, but of course they provide a lot of enjoyment, both during the building and alignment process, and when they are finished, they have that very special touch, you know, that very special sweet, mellow sound on the headphones that only comes from a radio that you have built yourself. I have no less than 10 easy-to-build radio receiver circuits, both with solid state components and with vacuum tubes, so you can send me an e-mail or a postcard to ask for some of those popular circuit diagrams. Among the most popular ones requested to are the simple two-vacuum-tube regenerative receiver, the four fiel effect transistors radio, and the several variations of the REGENERODYNE, a receiver that has a conventional superheterodyne front end, but instead of using a standard IF amplifier chain and detectors, uses a regenerative detector to replace both the IF amplifiers and the detectors. Send for the diagrams, start collecting the parts, and when you are ready to start building, if you are not experienced in assembling your own electronic gear, go to your local radio club and find someone that has done it before.... that's the best way to learn, and to avoid frustration... as another radio amateur or electronic hobbyist can guide you trough the early steps of homebrewing saving a lot of headaches in the process!
For example, the younger generation is not familiar at all with vacuum tube technology, so they usually need help when working with nostalgia radios!!! And by the way, it is amazing to see how well newbies do with their vacuum tube shortwave radios... a young radio amateur who lives about four blocks away from my QTH, Nelson, CM2NH, learned how to work with his vacuum tube single side band rig in a few weeks, and he is now helping others who are using similar radios, which can be obtained locally just for the asking as their users changed their equipment to highly sophisticated digital radios... A lot of Cuban amateurs have succesfully modified both vacuum tube and solid state commercial communications equipment for the ham bands!!!
Now let me insist on this, radio is a hobby where you learn by doing... it does require that you solder components, measure voltages, check the alignment of tuned circuits etc. etc. to really become proficient in the practical side of the hobby... Here is another good example...this Saturday CO2FU, Carlos was testing the KK-4 two meter band skeleton J antenna that he made from my own design... He, Zamora CM2XZ and myself, plus several other amateurs who were listening to the tests, spent about 2 hours adjusting and testing the KK-4 antenna, until the standing wave ratio was a nice and low 1.05 to 1 on 145.200, and Carlos, CO2FU, could run his handie-talkie using the low power position while still accessing a repeater located some 55 miles to the West of Havana. This antenna, the KK-4, is a real simple two meter band low-cost system that is built using a length of PVC pipe and copper wire. It is fed with 50 ohm RG58U cable for short runs, and if you need to run more than about 10 meters or 33 feet of coaxial cable to the radio, then one must use lower loss RG8 or RG213.... The KK-4 two meter band low-cost antenna uses a coaxial choke balun to cancel unwanted radiation from the outer part of the coaxial cable downlead shield, and today proved once again that it is a very nice weekend project indeed. As a matter of fact, when Carlos CO2FU and myself finished running the tests, several hams who listened on the repeater while we ran the test asked for all the data needed to build the KK-4, as they witnessed the tremendous difference when accessing the far away repeater with the handie talkie's rubber duck antenna and with the KK-4....
If you are already a ham radio operator and have a 2 meter FM transceiver, Arnie Coro's KK-4 Skeleton J antenna is a very nice weekend project to enjoy. Materials for building a KK-4 will cost very little, just a 2 meter long, about 6 and a half foot. PVC pipe with a diameter between 30 and 50 milimeters -- that is, from about one and a half to two inches outside diameter, a length of no.14, no.12 or no.10 bare copper wire, a length of RG58-U 50 ohm coaxial cable and an appropriate connector are all the materials needed... Send for the "How to build the KK-4 instructions manual" via e-mail to arnie@radiohc.org, or via AIR MAIL, a send a postcard to ARNIE CORO, Radio Havana Cuba, Havana, Cuba. Building your own KK-4 two meter band skeleton J antenna is a lot of fun, and your little handheld FM handie talkie will say thank you, as the KK-4 will extend its range a lot!!!!
You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and YES, you should send your signal reports, comments and new ideas, plus any radio hobby related questions to arnie@radiohc.org or via AIR MAIL, send a postcard with your Radio Havana Cuba QSL card to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Now item four.... Crystal radio receivers are a lot of fun to operate, and they do not need batteries at all... when you make a crystal radio using a very high Q coil for its tuned circuit, the sensitivity that can be achieved is unbeliveable. High Q coils are not easy to build, but if you have patience, use LITZ wire and a low-loss coil form, you will end with a coil that is NOT A MINIATURE DEVICE AT ALL, but that will certainly be very efficient... I make my own LITZ wire, which is nothing more than many strands of very thin enamelled insulated wire assembled into a rope-like wire.... Using 20 strands of number 30 enamelled insulated magnet wire, the homebrew LITZ wire seems to work quite well, and the high Q coil built with it works wonderfully... My latest high Q coil for a crystal receiver is about 5 centimeters diameter (about 2 inches) and is 10 centimeters (about 4 inches long). Winding that coil with the homebrew 20 by number 30 LITZ wire, my crystal set picks up all local AM broadcast stations using a very short length of wire for an antenna, and at night, when connected to an external inverted L antenna, it has picked up AM broadcast stations from no less than 5 countries -- Mexico, Jamaica, Bahamas, the United States and Colombia... an amazing achievement if you understand that this radio uses absolutely no external power. The crystal detector provides all the audio that you hear on the 4000 ohms high impedance headphones which, by the way, are essential for this kind of receiver!
Amigos, this is the weekend edition of Dxers Unlimited, and here are some news items:
Recovery efforts continue for the Oscar 40 amateur satellite, and so far the abnormally high spin rate is going down... BUT, do keep your fingers crossed, as no one can really know exactly the damage sustained by the spacecraft during the abnormal firing of one of its rocket propulsion engines... so far, only one transmitter is on the air, and ground controllers must still wait to gain better control of the satellite to be able to run complete tests of all the onboard systems...
Another radio news item... DIGITAL RADIO MONDIALE consortium still to announce the first set of standards for the proposed digital radio system that may operate using standard AM and FM broadcast transmitters... Tests run from several transmitter sites have only provided information to engineers equipped with special receivers, and it was obvious that some of the tests were running different digital configurations... so, we must just sit and wait until the first Digital Radio Mondiale standard is made public!
And now amigos, just before going QRT, here is Arnie Coro's HF plus 6 meters propagation update and forecast... Be on the lookout for possible disturbances that may be produced by the more recent solar flares. The 6 meter band Trans Equatorial Propagation season is now in full swing, something that those who worked the Easter Island station now know very well!!! The spring equinoctial DX season is now also, of course, in full swing, and this will last for the next four or five weeks.
Sunspot number for Saturday was 113, no coronal holes are visible, and the three thousand kilometer maximum useable frequencies were hovering around 40 megaHertz late Saturday morning... of course, all along North-South paths... For short wave listeners having a nice time at the Kulpsville Festival, a special HELLO FROM HAVANA AMIGOS!!! Hope you all have a nice time there, and if you hear this HELLO there at Kulpsville, send me an e-mail to arnie@radiohc.org for a special QSL card!!!
prepared March-10-2001; transmitted March-12-2001 17:11 EST
Arnie Coro CO2KK
Havana, Cuba
March 10, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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