RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, FEBRUARY 2, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos! Welcome to the radioaficionados show at Radio Havana Cuba! Join me for the next seventeen minutes of all radio hobby-related information and the most up to date HF plus 6 meters propagation forecast coming up, as always at the end of the program...
I am Arnie Coro, radio amateur CO2KK, your friend in Havana and here is item one: The SUN is still making headlines... Imagine solar flux now hovering near 260 units, and the daily sunspot count at a very high 256, yes you hear it right, 260 sunspots and we may see more!!! Naturally this has translated into some very interesting propagation conditions, that include phenomenal worldwide 50 megahertz amateur band openings and almost total absorption of radio waves during the daytime at some locations...
Item two: Yes, I am catching up with the e-mail, but amigos, even working until very late in the evening answering your radio hobby-related questions is not enough, seems like I will need a 30-hour-long day to be able to keep up with the great number of e-mail messages and letters received, and as always, I try to answer the questions in the best possible and easy to understand way... Sometimes the answers go on the air, sometimes not, and the reason for not including all of them on the air is that, even after the 3 more minutes we got last year, it is simply not enough air time, amigos!!! So be patient if you are still waiting for an answer to a technical question, I do plan to catch up during this weekend...
Item three: Someone suggested that I should sit down and design a no-frills, low-cost amateur radio transceiver -- actually the person said that I should design not one, but two low-cost rigs that could be easy to assemble and will help many would-be amateurs in Third World nations to go on the air... More about some ideas around the real possibilities of a low parts count rig for newcomers in Third World nations, that could also be useful in developed countries, later in today's weekend edition of Dxers Unlimited, reaching you on the air and on the web. Our URL for the live audio stream is www.radiohc.cu; you can listen via the INTERNET by connecting to www.radiohc.cu live audio feed...
Item four: I received a very nice message from Canada, and yes, our Toronto friends think that the students will certainly enjoy building a regenerative receiver as I suggested during our mid-week edition of Dxers Unlimited, so amigos, you will soon receive the data not about one, but about two easy to build short wave radios that young persons can assemble under the supervision of a more experienced radio hobbyist...
Stay tuned right on this same short wave frequency, or keep your dial-up, DSL or cable connection for more radio hobby related information coming to you from Havana in a few seconds, Margarita Delgado is the sound engineer and producer at RHC studio seven... I am Arnie Coro, radio amateur CO2KK...
Our easy-to-remember e-mail address is arnie@radiohc.org and yes, amigos, we do enjoy a lot reading your reports and comments about the program as well as the radio hobby-related questions that you may want to ask...
Here is now item three in detail: A long time ago, I heard about a nice project sponsored by IARU, the International Amateur Radio Union, that was promoting the design of a kit, a simple single band transceiver kit that could be sent in a small box via AIR MAIL to radio clubs in Third World nations which could then deliver them to would-be radio amateurs, and help them build and align the radios... But, unfortunately I lost track of the project, and as you may realize there is still a great need of such a project... Past efforts along this line have had some problems, especially the use of very sophisticated electronic components that in case of a breakdown would be impossible to replace locally; and also, all attempts seemed to try to make the transceiver an ultra- or near-ultra-miniature radio, something that won't help at all with beginners...
So, last week I received an e-mail from Canada, asking what I thought about reviving this great idea, and sure amigos, we have done it already here in Cuba, with our JAGUEY double side band plus CW 10 watt transceiver that is now undergoing its REVISION NUMBER 5, so we are calling it the Jaguey FIVE, as it generates 5 watts of CW... The Jaguey FIVE is a low parts count, not miniature, easy to build single band transceiver that uses readily available components, instead of sophisticated state of the art parts...
In order to please the friend who wrote about this topic, here is a brief description of our Jaguey FIVE and by the way, Jaguey is the name of a town, actually it is Jaguey Grande, or big Jaguey, and the Jaguey is a beautiful tropical tree... The original Jaguey transceiver originated in that Matanzas province town about 15 years ago, and as I said, the little radio is now undergoing its REV 5 or revision 5 of the original design... Well, here goes the description:
The receiver part starts with a simple yet effective RF attenuator, then it feeds a bandpass filter made of two tuned circuits... we use shielded IF transformers from old TV sets 4.5 megaHertz audio chains... A simple bipolar transistor grounded base amplifier feeds a homebrew double balanced mixer... and we "discovered" quote, unquote, that the antenna balun transformers used in TV sets, the 300 to 75 ohms baluns, had a ferrite core with two holes that makes a wonderful broadband transformer for the double balanced mixer...
We use computer diodes removed from defunct ISA old computer cards and motherboards and developed a very simple test jig to match the diodes... The double balanced mixer is fed on the other port from a simple three transistor oscillator, of which we have two versions, one using three NPN bipolar transistors and the other one using an FET oscillator followed by two bipolars... at the output of the mixer we have AUDIO, as this is a direct conversion receiver, amigos!!!
Now we amplify the audio using discrete components and again we have two versions of audio filters, one with bipolar NPN transistors and the other using a very common operational amplifier IC... The audio power output stage also is available to the builder in two versions, one using discrete components and the other using an integrated circuit audio amplifier that is locally available here in Cuba and produces a booming 2 watts of audio, with a lot of gain and rather low noise!
Well, that's why I will describe as a flexible design... again, no attempt is made to make the Jaguey single band amateur transceiver a miniature rig, as miniaturization is definetely not for beginners!!! In our upcoming mid-week edition of Dxers Unlimited, I will describe the transmitter section of the Jaguey which, as expected, uses the same variable frequency oscillator.... I think that version 5 of the Jaguey transceiver could very well be made available in kit form, with large-sized and easy to assemble circuit boards. Version 5 uses three circuit boards, one for the receiver, one for the VFO and one for the transmitter, so the newcomer can assemble just the receiver and start listening to amateur radio communications before having his or her own ham license!!!
You are listening to the weekend edition of Dxers Unlimited coming to you from Havana on the air and on the web at our Dxers Unlimited website and also avaialable via our easy to subscribe low traffic volume mailing list....
Now here is item five, our ever-popular "you have questions and Arnie tries to answer them." Here is today's question from a listener who is also an audio fan: Arnie, noise is spoiling my audio amplifiers, and it seems to come in via the power lines... does your advice about reducing noise on the radios apply in this case?
Well, amigo, some of it does apply, and you may want to try first of all to use a one-to-one ratio isolation transformer with a Faraday shield winding to feed your HI FI audio equipment... Such transformers are not usually available off the shelf, so you must either wind it all by yourself, something I won't recommend if you are not an expert, or order one from a certified special transformer manufacturer, and in that case, be prepared to pay a lot of money for a typical five hundred volt ampere or one thousand volt ampere one-to-one isolation transformer with a Faraday screen winding between the primary and secondary. BEWARE, this cannot be an AUTO-TRANSFORMER... it must be a transformer with two completely isolated windings, and with the FARADAY Screen wound in between the two...
A well-built isolation transformer is a lifetime investment, and a MUST for the critical audiophile who jumps out of his seat when a small spike coming via the power line spoils the nice music that he is listening to... If you want more information about how to calculate those transformers amigo, just drop me an e-mail to arnie@radiohc.org and I will be happy to send it to you.
BY THE WAY, such one-to-one isolation transformers with the FARADAY shield winding must have the FARADAY shield grounded properly to a low impedance ground, and remember that the FARADAY shield winding has only one connection; the other end of the winding is left floating!!! Using a one-to-one isolation transfomer to feed your electronic equipment is a very good idea, and I have added them to some of my friends' amateur radio stations, finding that those transformers do help to reduce the noise level, especially on the 160, 80 and 40 meter bands... As always, if you have any radio hobby-related questions, just send them directly to me at: arnie@radiohc.org
And now amigos, at the end of the show, here is our exclusive and not copyrighted HF plus 6 meters propagation update and forecast:
PROPAGATION ALERT for 6 meter band operators!!! Monitor 6 meters as much as possible as the very high solar flux and geomagnetic disturbances are enhancing F2 layer propagation on 6, 10 and 12 meters during the next two to three days... Solar flux is near 260 and the smoothed sunspot number is at a really outstandingly high figure of 201... Cycle 23 is certainly having another peak, and this one looks much broader than the previous year 2001 peak months...
For short wave listeners around the world, the 19 meters or 15 megaHertz band is open now 24 hours a day, bringing in a lot of DX...
Look for Radio Havana Cuba's spanish language broadcasts on 15230 kiloHertz from 00 to 05 UTC and on 15250 kiloHertz from 1200 to 1400 UTC... Both are beamed approximately to our South, but due to the excellent propagation are widely heard around the world...
See you on the amateur bands, presently monitoring 28.885 and 28.500 during the local daylight hours, and listening and calling CQ around 14200 during my local evenings... Hope to have a nice QSO, amigos!!!
Prepared 02-Feb-2002; received by NY Transfer News 07-Feb-2002, 09:43 EST
Arnie Coro CO2KK
Havana, Cuba
February 2, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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