Radio Habana Cuba: Dxers Unlimited Mid-Week edition for September 26, 2000
By Arnie Coro, radio amateur CO2KK
Hi amigos! Are you enjoying the excellent short wave propagation conditions? SURE! We have had no less than five days in a row of outstanding DX, and it looks like we are going to have at least three to five more extra days of very high maximum useable frequencies. BUT, the huge region 9169, the SUPER SUNSPOT that can even be seen with the naked eye via special filters, is still very much like a sleeping giant... and now it is past halfway the solar disk without producing an M or X class solar flare!
Item two: this is for those of you that do no have INTERNET access, YES, you can send for Arnie Coro's RADIO HOBBY INFO PACKAGES via AIR MAIL. Send your requests to Arnie Coro, Radio Havana Cuba, Havana, Cuba. YOU can select between the SIMPLE RADIOS INFO PACKAGE, the SIMPLE SHORT WAVE ANTENNAS INFO PACKAGE and the MAGNETIC LOOP INFO PACKAGE, and soon we will have another one available dealing with HOMEBREWING RADIO GEAR.
Item three: Radio Nederland is dropping MEDIA NETWORK, according to a press release, the popular show will go off the air soon.
Item four: You have questions and Arnie has the answers coming up in a few seconds, after this short musical interval; the sound engineer and producer is Margarita Delgado, I am Arnie Coro in Havana; stay tuned, there is a lot of radio hobby related information waiting for you here....
The name of the station is Radio Havana Cuba, this is Dxers Unlimited, our twice-weekly radio hobby show that also can be read on the INTERNET at our Dxers Unlimited website.
Here is item four: YOU have questions, and sure, I try hard to answer them, this one from a listener in the USA; here is the question: Arnie, you talked about recently about a Cubical QUad antenna for the 900 megaHertz amateur band; can this design be scaled for the 800 megaHertz cellphone frequencies? And question number two: how many elements do I need to obtain really good gain and directivity?
ANSWER to number one: YES, you can build a very nice cubical quad antenna for the 800 megaHertz cellphone band, and with anywhere from 4 to 8 elements it will provide a lot of gain and directivity IF, and here is the IF, again IF you build the antenna very, very carefully, and then tune it properly using high quality measuring equipment for that frequency range. In other words, the dimensions at 800 to 900 megaHertz are really very critical, so you have to be a very good antenna constructor, and measure everything right to the one millimeter mark... AND don't forget that increasing the effective radiated power of cellphones may be forbidden by cell phone services providers, or may require a special permission from them, something which is quite logical because with a high-gain antenna, you may be hitting not one, but two or more, cells at the same time, causing a lot of trouble to the system.
With regard to question two, my advice is not to go above 5 or maybe 6 elements at the maximum, use a non-conductive boom and elements made of highly conductive solid copper wire. YOU may find more information about similar antennas used for the amateur 70 centimeter and 33 centimeter bands in amateur radio antennna handbooks. So amigo, there you are-- it is not an easy task, but in some instances a 4- or 5-element cubical quad may be used for accessing the cellphone system from a faraway location during an emergency.
NOW, you can achieve practically the same results with a simpler and mechanically more rugged antenna -- YES, a 4- to 6-element YAGI for the cellphone band is both easier to build and tune up, although, again, tuning up a YAGI or a QUAD at such high frequencies is not an easy task!!!
Item five: This one for homebrewers who are gathering parts from old radios at fleamarkets and hamfests, to build NOSTALGIA vacuum tube radio equipment... During the past two weeks I tested a circuit by the famous American radio engineer Frank Jones.... It appeared in a 1936 Handbook that he wrote, and amigos, let me tell you that this push-pull crystal oscillator is an outstanding circuit. Built using an easily available double triode tube, and a recycled computer card quartz crystal, it has proven to be a CHAMP. Courtesy of a labor of love of many amateur radio enthusiasts who are carefully gathering all the information from radio books and magazines from the nineteen-twenties and 'thirties, the push-pull crystal oscillator circuit is now available on the world wide web, and the parts needed for homebrewing a version of this extremely interesting circuit are rather easy to find, and they are not very critical. In other words, the circuit is tolerant to parts value changes and still works very well. With a 6J6 double triode, running 150 volts on the plate, I obtain about 1 watt of clean CW carrier on the popular 40 meter amateur band, and so far have made several contacts with other Cuban amateurs during local daylight hours...
A GLOWBUGS TRANSMITTER, with a single 6J6 and running from a walwart supply for the filaments and a 150 volts high voltage obtained via a one to one isolation transformer and simple rectifier and filter network, can be built in a few hours and there is something outstanding about this circuit. It will oscillate even with a very sluggish quartz crystal... INTERESTED??? Want to know more about NOSTALGIA receivers and transmitters that can be easily built? THEN, just send me an e-mail to arnie@radiohc.org, and I will send you a list of websites -- really interesting websites that you can visit while surfing the net to learn more about these wonderful circuits that are easy to build and a pleasure to operate...
Item six: As solar activity stays above the 200 solar flux mark, there is a very interesting effect, which scientists describe as the "pumping effect" -- this means that the more days we see solar flux figures above 200, the higher daily maximum useable frequencies are going to be also; this is due to the difference between the breakdown of atmospheric atoms into free electrons and their nuclei, and the recombination process that takes place when the ionosphere is not under the effects of solar radiation. This is why, after three to five days of a rather high solar flux, we begin to see the 10 meter amateur band open very early in the morning local time, and then stay open even after local sunset... I said back in August that the next two or three 27 solar rotations were going to be really decisive for this Solar Cycle Number 23, and I wasn't wrong... no one was expecting this dramatic increase of activity after September 20th, and now we must really pay a lot of attention to how this solar rotation ends, and what happens during the next two!
Amigos, the radio hobby is unique... there are but a few hobbies in this world that can be enjoyed with such a little investment... I have a friend who keeps a very special logbook devoted to all the DX stations that he has heard in a three-transistor homebrew receiver. So far, in about three years' time, his logbook has more than 300 stations from 25 different countries on the AM broadcast band, from 530 to 1700 kiloHertz. See, his radio receiver is a very inexpensive one, it's homemade and uses only three field effect transistors. I have available here a 4-transistor improved version of my friend Carlos' little radio, which is available to Dxers Unlimited's listeners just by asking for it! Send for the 4-transistor Field Effect Transistor Radio Circuit Diagram, via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba, and via e-mail to arnie@radiohc.org. SEE, even with one single homebrew radio that can be built from even recycled components, you can really enjoy this hobby a lot! There are more than 50 ways of having a good time with radio, from hunting for DX on 10 meters using low power or QRP amateur radio equipment, to picking up faraway TV stations using meteor trails to send the signals back to Earth from hundreds of miles away!!! YES, radio is a very special hobby, and now that we have both low-cost solar cells and the Bayliss hand-cranked power generator, many millions of people in underdeveloped nations can enjoy the tremendous social benefits of radio broadcasting without the use of expensive batteries.
And now, just before going QRT, here is Arnie Coro's exclusive and not copyrighted HF Plus 6 metes propagation update and forecast: Solar flux will continue to be above the 200 mark for maybe two or three more days, but once the huge 9169 sunspot region turns around the Sun's limb, we will surely see a fast drop in the daily solar flux figure. We may see an increase in the daily geomagnetic field figures due to the possible impact of protons that were ejected from a recent solar flare, but I don't think this one is going to be a signficant event. We must still wait and see if the huge solar active region 9169 decides to wake up and start to generate flare activity... The chances for M class and even X class flares are still very high and if they do occur, we may see one of the most important geomagnetic disturbances of cycle 23.
Enjoy the excellent 220 plus solar flux, and remember that when the A index is up, the way to go is UP, moving to the higher frequencies, where the effects of ionospheric disturbances will provide some really interesting DX opportunities. Don't forget to tell me what you think of this show; send your questions and ideas for a better Dxers Unlimited via e-mail to arnie@radiohc.org or via Air Mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Arnie Coro CO2KK
Havana, Cuba
September 26, 2000Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
To Arnie Coro's Dxers Unlimited
Back to NY Transfer's RHC main page