RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, April 6, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados! Welcome to the weekend edition of your favorite radio hobby program, the one and only that covers from just above direct current to the ultraviolet light waves, because -- YES -- at least in theory, frequencies as low as one Hertz or cycle per second, and as high as the far end of the ultraviolet region of the spectrum are, after all, forms of electromagnetic radiation.... SURE, this is a wonderful hobby, that can be as easy and relaxing as short wave listening, as exciting and exhausting as working ham radio contests, as dangerous and rewarding as staying in a small island in the middle of a huge tropical hurricane, or as enjoyable as collecting QSL cards from ham operators around the world. You can have a good time with inexpensive radios, or spend a lot buying sophisticated equipment, you can certainly be proud of homebrewing your own radio receiver and antennas... Because the radio hobby is an ever-changing one, providing challenges that once conquered you will remember forever....
SI AMIGOS, welcome to Dxers Unlimited's weekend edition, the solar flux is above the 200 mark, and the higher frequency bands are wide open during your local daylight hours and beyond....
Now here is item one: The youngest amateur radio operator who works the satellites is in Houston, Texas -- the 12-year-old daughter of Bruce Paige, KK5DO, an avid satellite enthusiast who has been on the air via ham satellites for the past two years, and SURE, I do expect to be able to talk to her via UO14, the FM repeater satellite that delivers so strong signals from space several times a day.... By the way if you hear the callsign W5BTS on the UO14 downlink, that's her, amigos!!!
Item two: The ever-popular you have questions and Arnie answers them section of Dxers Unlimited today will be devoted to the DISCONE antenna, a unique antenna system by all standards...
Item three: Listening to the 60 meter tropical band...
Item four: Old MFM hard drives, the big ones are a treasurechest of nice electronic components to recycle... and at the end of the show, as always, Arnie Coro's Dxers Unlimted's HF propagation update and forecast...
Margarita Delgado is the sound engineer at the audio mixer board; this show was taped earlier Saturday at around 19 hours UTC from my shack, so you will notice that the audio has a particular and intentional enhancement of the voice frequencies... Stand by for more radio hobby related information, I'll be back in a few seconds...
You are listening to the weekend edition of Dxers Unlimited, and here is Item two, a question: Arnie please tell me more abouth the discone antenna, I read something about its unique broadband characteristics, and want to know if it will work with my VHF-UHF scanner receiver...
Well, amigo from Chicago, Illinois, USA, the DISCONE is a unique antenna system by all standards... When properly designed and carefully built it can provide a fantastic 10 to 1 frequency coverage... yes you heard it right, a DISCONE antenna can be made to cover say from 100 megaHertz all the way up to 1000 megaHertz or ONE GIGAHERTZ... A discone antenna for attaching to a VHF - UHF scanner that covers from 30 megaHertz all the way up to 900 megaHertz or even higher does not exist, so you will need to build two or three of them.
For the VHF lo band, 30 to 50 Megahertz, the amateur 6 meter band, the low band TV channels, the FM broadcast band and the very interesting to monitor aviation 108 to 136 megahertz band will require building a discone antenna with an optimized coverage of from 30 to 150 megaHerz, as you see it is a nice 5 to 1 frequency ratio... This discone is a large antenna, and you will spend quite some time constructing it, but the wonderful thing about DISCONES is that once built, they will not require any adjustments whatsoever if you have constructed them properly...
Your second DISCONE antenna will cover from 100 to 500 megaHertz, and is going to be much smaller and easier to build.... and if you really want to enjoy the low-angle radiation from the discones, then you should build a third one that will cover from 300 to 1200 megaHertz. That's because as the frequency of operation moves up, the discone's antenna vertical radiation pattern starts to show an increasing upward tilt, something that is good in the case of the aviation band, but not useful at all when you are attempting to listen to terrestrial mobile or fixed stations...
The discone antenna is really a unique matching system that is capable of providing a broadband transition between the 50 ohm coaxial line used to feed it and the 377 ohms impedance of space... Antenna gurus will tell you that it is something really outstanding from the theoretical point of view, something its inventor, A.G. Kandonian, knew well when he applied for a patent 'way back in 1945. By the way, the original scientific paper, also written by the inventor of the discone, was published in 1946, and for those of you who enjoy reading technical literature, here are the details: The author is A.G. Kandonian, and the title of his paper is "Three new antenna types and their applications," published in Proceedings of the Institute of Radio Engineers (IRE), February, 1946, pages 70 to 77... Sure, for antenna fans it is a very interesting and informative scientific paper, but be ready to deal with some fancy mathematics!!!
So, amigo from Chicago, you can look up more practical information about the discone wideband vertically polarized antenna available in many of the radio antenna handbooks... All I can add is that the time invested in learning about, understanding and building your discone antennas is worth every second, and I must add that this antenna will provide excellent performance when transmitting, too, without requiring the use of antenna tuners...
The DISCONE, an antenna every VHF and UHF enthusiast must know about and have at least two of, built and installed... It is certainly an amazing antenna system by all standards...
QSL, QSL, QSL on the air to the many Dxer Unlimited's fans who are reporting our new 9655 kiloHertz SSB frequency on the air from 05 to 07 UTC with our English language broadcast -- you can tune our programs from 05 to 07 UTC on three frequencies, two using A3 AM modulation, on 9550 kiloHertz and 9820 kiloHertz, and now this new frequency 9655 kiloHertz on the 31 meter band using upper side band suppressed carrier modulation...
Now here is Item three: Yes, this one of the two times every year when you will want to explore the 60 meter Tropical Band for DX, but this spring equinoctial DX season is not one of the best, due to the fact that solar activity is still way up... Ionospheric absorption of the lower radio frequencies is higher when solar activity is above 120 units or so. Since the start of this year's first equinoctial season a few weeks ago, the daily solar flux figure has stayed way up, and that's the reason why you are noticing that the 60 meter Tropical Band stations are not as strong as they should be during this period.
By the way, scientists have now confirmed that the solar cycle had a very clear second peak during the month of December of the year 2001, and they are puzzled, because helioseismic analysis is showing two more big sunspots on the other side of the Sun, soon to be facing towards the Earth... Cycle 23 continues to extend its peak activity period, and with that, radio amateurs are enjoying an extended 10 meter band DX season, and also a unique 6 meter band worldwide DX that was to say the least, unexpected!!!
Monitor the daily Maximum Useable Frequency as it moves up and down, by carefully taking note of the stations heard at the highest frequency at a given time of the day, and you will soon learn how to make the best possible use of what is left of this solar cycle's peak... and beware, as it may still bring in another big surprise... according to some scientists, cycle 23 may soon show a THIRD PEAK, and if this happens it will make it a very unique solar cycle, indeed...
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, and we do QSL 100 percent here, amigos, just send an AIR MAIL postcard with your signal report and comments about this and other RHC programs, mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba, and if you have e-mail, send mail to: arnie@radiohc.org
Radio and electronic experimenters be advised: grab all those old MFM hard drives from the early days of personal computers... Yes the MFM hard drives, the big ones... remember them -- 10 megaBytes storage capacity the size of a shoebox? Well. those MFM drives will provide you, the radio and electronics experimenter, with a treasurechest of high-quality, easy-to-recycle electronic components, including some nice power Field Effect transistors, diodes, resistors, and capacitors... Don't let them go to the dumpster... look for those old XT machines and similar ones...then open the hard drives and extract the circuit boards inside.... sit down, warm up your soldering iron, and relax by desoldering a lot of nice electronic components that you can use for your next homebrew project!!!
And now, amigos, as always at the end of the show, here is Arnie Coro's Dxers Unlimited's HF propagation update and forecast: Cycle 23 gave us yet another surprise by moving once again above the 200 solar flux units mark, and there are chances for more solar flares during the next several days. During the next three to five days we will enjoy very high daytime maximum useable frequencies, and trans-equatorial propagation for the 6 meter band is a good possibility, too. Due to the high solar flux, the lower frequencies won't be so good, but who cares when one sees the 18 megaHertz, the 17 meters ham band, open at three o'lock in the morning local time?
Send your radio hobby related questions to arnie@radiohc.org, and keep looking for unusual propagation conditions associated with possible geomagnetic disturbances that may happen after Tuesday UTC...
Arnie Coro CO2KK
Havana, Cuba
April 6, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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