Radio Habana Cuba: Dxers Unlimited weekend edition for March 17, 2001
By Arnie Coro, radio amateur CO2KK
Hello, my friends! Welcome to the excellent short wave propagation conditions provided by the Spring Equinox here on our hemisphere, and the Autumn Equinox down there!!! I am Arnie Coro, radio amateur CO2KK, your friend here in Havana, and it is certainly nice to have you listening to Dxers Unlimited, which is now extended to 18 minutes of air time!!!
Here is item one: Nice, quiet, very low noise levels, BUT -- solar activity MUCH LOWER than last year at this time... So, enjoy the spring equinoctial DX season with an estimated solar flux of around 140 units, which is still rather nice and provides good DX conditions even on 10 meters...
Item two: No one can imagine how many radio hobbyists enjoy homebrewing radios... especially after they have that unique once-in-a-lifetime experience of listening to a radio that they have just finished assembling. I always remember the face of a newcomer to the hobby when their first radio starts picking up signals.... and the fascination seems to last forever... but nowadays radio receiver circuits with so-called state of the art technology are practically out of reach of even the very advanced amateur... that's why much simpler yet effective circuits are so popular among homebrewers.... Here in Cuba, the Islander double-sideband amateur transceiver started a new era of home construction, which was later followed by the Jaguey, a more advanced solid state single band transceiver... Today, we are looking at simple CW transmitters that can be built mostly, if not completely, from recycled parts...
Item three: Quartz crystals provide the experimenter with a highly stable frequency source, that's why quartz crystal controlled transmitters are easier to homebrew than those using variable frequency oscillators... I'll tell you more about quartz crystals and their close relative ceramic piezoelectric resonators later in today's weekend edition of Dxers Unlimited, your favorite listener-oriented, technically minded radio hobby show on shortwave and on the WEB!
This is Radio Havana Cuba... we are broadcasting our English Language programs using regular AM broadcast transmitters on several short wave frequencies, and we also provide Single Side Band service from 0100 to 0500 UTC on 11705 kiloHertz, upper side band, and from 0500 to 0700 on 9830 kiloHertz...
Now, let's talk about quartz crystals and ceramic piezoelectric resonators, which are used both as frequency setting elements and for building filters. As a matter of fact. one of the very interesting applications of piezoelectric devices is making filters that are very useful for both receiving and transmitting purposes. Amateurs nowadays can build their own single side band or CW filters, using computer grade crystals that are much lower in cost than standard transmitting crystals of yesteryear... The very popular ladder type filter, using crystals which are almost all on the same frequency, can be assembled and tested using homebrew instruments, and on-the-air results are really excellent. Of course, you can buy yourself an expensive SSB or narrowband CW filter, and it will provide nice results, but for the price of a commercial 2.7 kiloHertz bandwidth crystal filter, you can probably buy enough computer grade crystals to build maybe ten or fifteen homebrew filters, amigos! You can also obtain many quartz crystals by RECYCLING old or damaged electronic equipment.... computer motherboards and plug-in cards are a treasure chest of electronic components ready to be recycled, and among them, quartz crystals are always waiting to be carefully desoldered by the enterprising amateur... something that must be done CAREFULLY, as piezoelectric resonators can be damaged beyond repair by overheating them.
Radio amateurs use quartz crystals and ceramic piezoelectric resonators a lot, and these components form part of many homebrew projects. Sometimes you cannot find a crystal of a particular frequency, and so you have no choice but to order it... something that can prove to be rather expensive, as made-to- order quartz crystals are becoming more and more costly due to the fact that they require a lot of time to manufacture... That's why hobbyists are designing radio equipment that can make use of the computer grade crystals which are manufactured in great quantities and cost a lot less per unit... Quartz crystals and their close relatives, ceramic piezoelectric resonators are temperature-sensitive components; that's why in critical applications you may find them working inside thermostatically controlled ovens....
One of my favorite easy-to-build gadgets for the radio hobby is a frequency marker that provides a quick frequency check from a stable quartz crystal oscillator. I use a computer grade 10 megaHertz crystal oscillator and two integrated circuits that divide the frequency generated so that from the 10 megaHertz oscillator, markers are generated every one megaHertz and every one hundred kiloHertz. This is a very useful accessory when you are using an analog dial receiver, as it allows you to check your dial calibration every one hundred kilohertz... You can add another integrated circuit frequeny divider and generate a calibration mark every 10 kilohertz too, but usually you can do well with the every 100 kilohertz markers.
Here is Arnie Coro's advice: Quartz crystals and ceramic resonators are really useful for the radio experimenter, so every time you see one that can be transported to your junk box, by all means, grab it! You will soon have a collection of quartz crystals that will prove extremely useful for your radio experiments...
This is Dxers Unlimited's weekend edition, and here is item five: Our special 40th Anniversary QSL card is beautiful, amigos; you can send for it by sending a signal report and comments about today's edition of Dxers Unlimited to arnie@radiohc.org and Via Air Mail, send your request for our beautiful RHC 40th Anniversary QSL card to Arnie Coro, Radio Havana Cuba, Havana, Cuba, and if the signal report is correct, you will add a beautiful new QSL card to your collection....
And now that I am talking about QSLs, here is QSL on the air to Gordon Ball in Ottawa, Canada. Thanks, Gordon, for the report on our 6000 kiloHertz transmitter, which I passed along to the Chief Engineer.... QSL on the air to listener Frank Pagano, who picks up Dxers Unlimited from Washington, DC. Frank gives a very nice report of our SSB frequency on 11705 kiloHertz.... QSL on the air to England, to Martin Cowin in Brough, Cumbria, who picks up our 13750 kiloHertz frequency, which is beamed precisely to Europe.... QSL on the air from Dxers Unlimited to Tim Watson in Pittsfield, Masachussets, who sent a very nice report of our 6000 kiloHertz frequency picked up in late January. Sorry, amigo Tim, snail mail is really slow indeed.... QSL on the air to Liverpool, England -- George Smith stays up really late, and picks up our Eastern North America Beam on 6000 kiloHertz ar 0300 UTC, and he gave me a report of 44434 using the SINPO format. George uses a Yaesu FRG100 receiver.... QSL on the air to Saudi Arabia, listener S.M. Bandara also picked up -- and this is unusual -- the 6000 kiloHertz program to North America between 0100 and 0200 UTC with an SIP report of 433, which is remarkably good, considering that the antenna is not beamed in that direction.... Also QSL on the air to good friends Bruce Atchinson VE6XTC and Tim Rasch, who have sent several e-mail messages in the past several days....
Now item seven: A NEW version of the very popular ISLANDER double sideband and CW transceiver is now in the works here in Cuba. The ISLANDER is a low-cost simple rig that is built using mostly recycled parts removed from old TV sets. The new version of the ISLANDER includes an input attenuator and bandpass filter for the receiver, using DC -- that is direct current -- on the filaments of both the VFO and the Detector vacuum tubes, and an audio filter for the receiver. OH YES, the ISLANDER uses recycled vacuum tubes, which usually come from old retired TV sets. Cuban radio amateurs with their tremendous ingenuity have built several hundred ISLANDERS, and although I must admit that not all of them sound really good, especially on CW, it is really interesting to see how homebrew rigs can put you on the air at very low cost.
For those of you who are thinking about a solid state version of the ISLANDER, YES... it is a very good idea, and I am now working on it. So far, the circuit diagram for the receiver section of the transceiver is almost finished, following the original ISLANDER approach of using easy-to-obtain components. Here is the line-up for the SOLID STATE ISLANDER: An input resistive attenuator, which is very useful and easy to build, a double or triple tuned bandpass filter, feeding a radio frequency amplifier stage which uses two transistors in the ever-popular cascode circuit. The mixer uses four diodes and two ferrite cores that came from TV antenna baluns... The VFO, or variable frequency oscillator, is made using three transistors, and I have two versions -- one that uses an FET, and one that is made just with bipolar NPN transistors. The receiver's audio chain is made with a low-noise audio NPN transistor feeding an integrated circuit audio amplifier that is extremely popular here in Cuba -- the TBA210, which provides up to around 2 watts audio output. So with six rather common transistors and one integrated circuit audio amplifier, the solid state version of the ISLANDER will prove easy to build and the parts are also easy to find! I'll tell you about the Solid State ISLANDERs transmitter on our next edition of Dxers Unlimited....
And now amigos, just before going QRT, a reminder: My collection of REGENERATIVE and REGENERODYNE receivers circuits is yours for the asking... you may want to see some of these circuit diagrams, and I am sure that a few days later you will find yourself assembling one of them... Several Dxers Unlimited listeners are now picking up the show not with their solid state digital radios, but with their homebrew receivers built using the information that I sent them... send for the REGENERATIVE and REGENERODYNE receivers circuit diagrams to arnie@radiohc.org, and I am sure that you are going to enjoy building them from the very moment that you start collecting the parts...
Ready to copy? Sure, it's 18 minutes now, but they just sailed along like that, amigos! So now listen to Arnie Coro's Dxers Unlimited HF plus 6 meters propagation update and forecast: SUN about to reach the EQUINOX... it is now very, very near the EQUATOR. So, equinoctial propagation conditions are now in FULL SWING, but this year, solar activity is much less than during last year's Spring equinox. Solar flux is around 140 and going DOWN. The smoothed sunspot number today is 94, the A index is a nice and low 03, something that makes LOW FREQUENCY absorption very low. The K index was 1 on Tuesday morning and it is likely to remain between 0 and 2 during the next several days. The number of sunspots during the past six days were 139, 174 (which marked a peak), 110, 159, 126 but on Tuesday, it took a nosedive to just 86... So, as you may see, during the same week we have had a peak in sunspot number of 174 and a rather low 86, too...
DXing conditions for the 6 and 10 meter bands are nice, and the 12, 15, 17 and 20 meter bands will provide radio amateurs with excellent worldwide DX during the next three to five days. Short wave listeners will enjoy nice conditions on the Tropical Bands, and AM medium wave band Dxers will be able to log in quite a few stations, as the combination of equinoctial enhancement and low solar activity will certainly help! See you on the ham bands, and next Tuesday and Wednesday at the mid-week edition of Dxers Unlimited!
prepared 17-Mar-2001; transmitted 17-Mar-2001 14:43 EST
Arnie Coro CO2KK
Havana, Cuba
March 17, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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