By Arnie Coro
radio amateur CO2KK
Hi amigos radioaficionados all around the world, plus those ham radio operators aboard the International Space Station, who use part of their spare time to relax talking back to other radio amateurs on the two meters band. I am your host Arnie Coro, my amateur radio callsign is CO2KK and here is item one to the weekend edition of Dxers Unlimited... the daily sunspot number hovering around 115 units, while the solar flux is still slightly above 110 units. The Earth's magnetic field is quiet, so we will enjoy much better propagation conditions today and tomorrow, than those we had to deal with exactly one year ago. Nevertheless solar cycle 24 continues to be a well below average activity one... as we compare it with any of the five previous cycles.
Item two: Minimalist ham radio transceivers , designed around one , two or three transistors are both an electronics engineering challenge, as well as a real thrill to operate, but I warn you all NOT to expect immediate results from those very low power transmitters, especially when propagation conditions are poor. Designers of minimum parts count transceivers for the short wave amateur bands have achieved really outstanding results . I remember , several years ago, starting to gather the parts to build a PIXIE minimalist two transistors plus one audio integrated circuit transceiver, that I decided to build as part of the lessons to a group of students that wanted to pass their amateur radio license test. I thought that assembling PIXIE will be a good way of showing them how to solder, and as a matter of fact, it was possible to have at hand enough parts to build two PIXIES !!! Connecting the little circuit board to a power supply and to my 40 meters band NVIS dipole , brought quite a surprise, because I was really astonished to hear not one , but several CW stations on the 7040 kiloHertz frequency to which the PIXIE was tuned for both transmitting and receiving.
It was also interesting to do some improvements to the minimum parts count PIXIE transceiver, and actually use it on the air to make not only local contacts on 40 meters , but also several QSO's with stations in the USA and Canada. In our technical topics section today, I will be telling you more about minimalist transceivers in general and the PIXIE rig in particular. Stay tuned for more radio hobby related information, coming up from Havana, in a few seconds...
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This is Radio Havana Cuba broadcasting to the world via short wave and also on our streaming audio channel coming out from www.radiohc.cu, this is the mid week edition of Dxers Unlimited, and here is now item three... our technical topics section.
Let me now briefly describe the PIXIE two transistors plus an audio integrated circuit crystal controlled transceiver... The number one transistor is a crystal oscillator that is on all the time, both during receive and during transmit. The second transistor does double duty, when receiving it provides one of the two NPN junctions diodes that works as a mixer, receiving the signal from the antenna and mixing it with the oscillator's frequency. In other words it is working as a classic single diode product detector... The resulting audio output is fed to the LM386 audio amplifier integrated circuit, set to its maximum possible gain. During transmit, the second transistor acts as a power amplifier output stage, that in the case of my first PIXIE provided about one quarter of a Watt of radio frequency power to the antenna... A clever combination of circuits, stops the audio amplifier from working during transmit !!! After playing with the PIXIE for some time, I went forward to add a third transistor plus a audio volume control, something that proved to be a very nice improvement when receiving weak signals. What still amazes me is how both, the two transistors an the three transistors versions of the PIXIE minimum parts count transceiver could provide the possibility of making two way contacts on the 40 meters band , when propagation conditions were normal or better yet above normal.
The PIXIE is a very nice toy to build and a challenge to operate amigos !!!
You can learn a lot more about the PIXIE minimalist transceiver by just typing
P I X I E , PIXIE on any of the popular Internet search engines.
The PIXIE 2 upgrade, designed by Russian radio liubitel, that is radio amateur in russian, RV3GM is an excellent example of the optimum use of each electronic component, and among its features is the fact that it uses standard parts, as there is no rare onobtanium devices included !!!
By the way in favor of doing some radio hobby history, the original PIXIE design was first published by SPRAT, the British GQRP Club Magazine, that is now available as an extremely useful compact disc, that contains each and every issue from number one to number one hundred and thirty six in dot PDF format. For those of you that have been motivated by this technical topics section of Dxers Unlimited today, visiting the GQRP Club's website will further enhance your know how about this fascinating aspect of our hobby , known as QRP or very low power operation amigos !!!
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Hurricane Irene has done a lot of damage to the Bahamas and all along the East Coast of the USA, from North Carolina up to new England, and what is worst of all, , news came that so far more than 40 persons have died as a consequence of the transit of the storm along the highly populated Atlantic Seaboard. As electric power was cut off, and the telecommunications systems experienced high traffic and loss of facilities due to the hurricane, amateur radio operators once again volunteered to provide alternative communications to the disaster management crews. Here in Havana I was able to pick up several emergency nets operating on the 80 , 40 and 20 meter bands. Locally many ham operators used the 2 meters and 70 centimeters FM repeaters to help deal with the emergency. Due to the extensive damages done by the hurricane force winds and heavy rains first and later by tropical storm force winds plus more rains, it is expected that many areas of the affected states will be without electric power for periods that may extend to one or even two weeks... As we all remember the terrible tragedy caused by Hurricane Katrina six years ago, it was certainly a relief to watch how emergency preparadness was much improved, and that once again amateur radio operators were ready to operate with portable equipment, antennas and power back up systems for the duration of the emergency.
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QSL on the air, QSL on the air amigos... to all Dxers Unlimited that keep contacting me via the e'mail address inforhc at enet dot cu, again the contact e'mail direct to my computer is inforhc at enet dot cu, and YES, it is really great to receive your radio hobby related questions and comments about this and other Radio Havana Cuba programs... QSL on the air today to amigo Radames, radio amateur CL2ISS, who is a regular listener of Dxers Unlimited via groundwave... Radames workplace is the Cuban weather service, and he keeps our local ham radio nets up to date about all weather related events . QSL on the air to amigo Hue , who keeps his thermostatically controlled soldering iron always ready to try new circuits... Hue is listening on a solid state regenerative transistors radio that he built using standard parts... His favorite frequency is 6010 kiloHertz, that is on the air to the west coast of North America from 05 to 07 hours UTC... And yet another QSL on the air to long time listener Bob in Toronto , Canada, who likes to operate his ham radio station on the fifteen meters band whenever it is open. By the way Bob told me recently via e-mail that he was able to pick up the 11760 kiloHertz frequency with excellent signals during his late afternoon and early evening hours.
And now amigos, as always at the end of the show, here is our HF propagation update and forecast....The Sun is full of sunspots, but they are not really very active from a magnetic and radiation point of view... Anyway , the daily sunspot count has passed the more than one hundred mark for several days, and that is good news for all short wave radio fans, because it means that finally solar cycle 24 is much more active. Expect better propagation during the next two weeks amigos, and don't forget to send your signal reports and comments to inforhc at enet dot cu or via air mail to Arnie Coro , Radio Havana Cuba, Havana , Cuba
News 
By Julio Pérez | 
