RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, MAY 4, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados all around the world! You are now listening to the weekend edition of your favorite radio hobby program, this is Dxers Unlimited, and I am Arnie Coro, radio amateur CO2KK, your host here in Havana ready to share with you all about seventeen minutes of all radio hobby related information....
Here is item one: Another upsurge in solar activity, and heliosismic data show that there are lots of sunspots on the farside of the Sun, so amigos, we may be seeing yet another solar rotation with a lot of activity!!!
Item two: Specialized amateur contests that do not disrupt your weekend with the family and friends are becoming more and more popular, for one very good reason: you enjoy the thrills of a real contest for a few hours, and then the rest of the weekend can be spent with your family. Not too long ago, a ham radio friend told me that the four- or six-hour-long contests do require a lot of skill, especially those that let you select the four- or six-hour operating period!!!
Item three: FM band Dxing is becoming more and more difficult all over the world due to the continuos increase of the number of low power local FM broadcast stations that are receiving licenses from the radio regulating authorities. Even a 10 watt local with a 6 dB gain antenna will make DX impossible on its own channel and at least on the first two adjacent channels, that depending on how close to your location the low power FM station is.
Nevertheless, dedicated FM broadcast band Dxers are learning some of the tricks that AM band DXers use, like waiting for off-the-air hours that station engineers need to do equipment maintenance... By the way, the FM broadcast band sporadic E DX season has just started, but so far, the openings are few and far apart from each other.
Item four: Homebrewing your radios is a lot of fun, and there is nothing like listening to DX with your homebuilt receiver, or like working DX with your amateur radio rig which you have just finished building. More about homebrew radios later here at the weekend edition of DXers Unlimited, amigos...
And, as always at the end of the show, be ready to copy Arnie Coro's Dxers Unlimited's exclusive and not copyrighted HF plus 6 meters propagation update and forecast. Margarita Delgado is my sound engineer and producer at studio 7, this is Radio Havana Cuba....
Amigos, you are listening to the weekend edition of Dxers Unlimited, and here is our main feature for today: Arnie's advice about homebrewing your radio equipment. First things first... so don't attempt to start your homebrewing with a very sophisticated project, or without having the adequate tools at hand including, of course, your digital multi-meter!
You may perhaps want to start learning how to homebrew your radios by building one of the many kits now available, and as a matter of fact, that is an approach that I do recommend, because kits are an excellent way of learning about electronics.... Unfortunately some of the new generation kits are rather difficult to assemble due to the use of very small electronic components placed too tightly together, thus making your job of putting together the kit a lot harder. Here in Cuba, radio amateurs build a lot of their equipment, and something we all have learned is to homebrew our radios without any attempts to make them miniature sets!!!
Leaving enough space between the resistors, capacitors, integrated circuits, transistors, coils, crystals and other components has proven to be a very good idea, because it is a lot easier to put them together into something that will work, and also because when there is a breakdown, your homebrew set is a lot easier to repair...
Some Cuban amateurs have a second transceiver always ready for emergency communications, and that second radio is typically a version of the JAGUEY solid state double sideband transceiver, running anywhere from 3 to 10 watts, enough to communicate using a Near Vertical Incidence Skywave antenna system on the 80 and 40 meter bands... The homebrew JAGUEY is a quite straightforward design that allows you to upgrade the transceiver to a single side band set if you are able to obtain a single side band filter at a later date...
As a good friend likes to say, when you use a low power double sideband transceiver, no one realizes that you are also transmitting the unwanted sideband, as the other station's radio provides the filtering to pick up just the sideband in use on that specific band... In other words, if I am operating CO2KK with my JAGUEY on 40 meters, other stations using Single Side Band rigs will only pick up my lower sideband, as their transceivers will just chop away the upper side band when receiving....
Well, as you may realize, homebrewing a low cost double side band transceiver is not only a perfectly feasible project, but also one that will make your station ready to deal with communications emergencies, due to the fact that the JAGUEY needs just 12 volts from a battery to operate, and it draws very little current, even when transmitting. More about the JAGUEY and its most recent improvements in a few seconds, when Dxers Unlimited's weekend edition continues...
You are listening to Radio Havana Cuba, and amigos, if you happen to own a receiver capable of receiving single side band signals, try listening to our 11705 kiloHertz SSB broadcasts in English that start at 0100 UTC and last until 0500 UTC. Again our 11705 kiloHertz SSB is operating using upper sideband at reduced carrier, so that you can zero beat to the residual carrier for perfect reception... For those technically minded, we are running around 20 kiloWatts Peak Envelope Power, or PEP, with -12 dB carrier level, and the antenna is an array of dipoles beaming exactly North of Havana...
And now more about the JAGUEY double side band and CW single amateur band transceiver and its latest version... Among the most recent upgrades are the use of a triple tuned bandpass input filter and attenuator, which makes reception a lot better... Receiver incremental tuning, or RIT, was also added to the basic JAGUEY design, and the CW keying was improved by using a PNP transistor with wave shaping to key the rig...
Also, the NEW JAGUEY has an optional pair of audio filters, one for SSB and the other one for CW, so that the operator may switch from one to the other as required. The NEW JAGUEY also uses a simple but effective transmitter audio compressor that improves the punch of the signal quite a bit. And last but not least, some of the local enthusiasts have now built a very low-cost linear amplifier that uses recycled vacuum tubes to increase the output power of the JAGUEY to anywhere between 20 and 50 Watts...
One very interesting feature of the NEW JAGUEY is that once the newcomer to the amateur radio hobby finds a single sideband filter, the NEW JAGUEY can be readily adapted to be the "tail end" of a single sideband transceiver, so not even one component is lost from the original project. AH, and before I forget, the NEW JAGUEY is a very, very, flexible design because, for example, the receiver audio can be implemented with no less than three different circuits, a straightforward three transistor single ended audio amplifier, a more sophisticated push pull design using discrete components as the first one just mentioned, and the classic JAGUEY receiver audio module that uses a low noise audio transistor coupled to an integrated circuit audio amplifier, the TBA810 or A210 that happens to be plentiful here in Cuba...
Si amigos, yes my friends, oui mes amis... Homebrewing your radio gear is a lot of fun, and when propagation conditions are not good, then you just plug in the soldering iron, and start building your next project... By the way, I am working now on the NEW JAGUEY PROJECT circuit diagram and operating manual, and as soon as they are both ready, they will be posted at our Dxers Unlimited website for you to download....
One of the outstading features of this unique radio amateur transceiver is the fact that I have included a complete list of parts with sets of values that can be used without the circuit suffering from any degradation.... In other words, you may find right next to each component -- be it a resistor, capacitor, transistor or IC -- a number of options that you can use, making construction a lot easier... As many of you who already have built electronic equipment know very well, the lack of a specific value resistor, for example, can bring the whole project to a standstill, so is was why I spend a lot of time testing each NEW JAGUEY module to learn how the parts values could be changed around without degrading the performance of the transceiver!!!
The NEW JAGUEY receiver chain uses a switched three, four or five position RF input attenuator, followed by a two or three tuned circuit band pass filter, feeding a grounded base or grounded gate RF amplifier stage, that delivers its signal to a double balanced mixer acting as a product detector... audio from the product detector is fed to a low noise audio preamplifier that in turn feeds one of the two audio filters, which in turn feed the audio power amplifier module... The VFO is a very straightforward three transistor module, of which there are three different versions that you can choose from, depending on the parts that you have available. As a matter of fact, newcomers to the amateur radio hobby may build just the receiver part of the NEW JAGUEY and start listening to the 80 or 40 meter bands to pick up CW practice, and then after they obtain their license, they can build the transmitter module!
I'll tell you more about the NEW JAGUEY in our upcoming mid-week edition of Dxers Unlimited next Tuesday and Wednesday UTC days, when I will describe the transmitter chain of the NEW JAGUEY, the Cuban-designed, low-cost double sideband and CW transceiver....
And now, amigos, as always at the end of the show, here is Arnie Coro's Dxers Unlimited's HF plus 6 meters propagation update and forecast:
Solar activity is MOVING UP AGAIN, and both the number of sunspots and solar microwave flux are increasing... Heliosismic data show that we will have from a week to ten more days of higher activity, and don't be surprised if yet another big solar flare erupts during the next few days.
We all hope that the summer sporadic E season will finally take off, too. The best band for amateur radio Dxing during the local daylight hours should be 15 meters, while nightime DX on 20 meters is going to be plentiful for the rest of the summer...
Send your signal reports and comments to arnie@radiohc.org and VIA AIRMAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba
Prepared 04-May-2002; received by NY Transfer News 07-May-2002
Arnie Coro CO2KK
Havana, Cuba
May 4, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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