Radio Habana Cuba: Dxers Unlimited Mid-Week edition for September 19, 2000
By Arnie Coro, radio amateur CO2KK
Hi amigos! Welcome to the mid-week edition of your favorite radio hobby show reaching you via short wave and available also for reading at our Dxers Unlimited website.
I am Arnie Coro, radio amateur CO2KK, and here is item one: Geomagnetic disturbances triggered by coronal mass ejection provide very interesting propagation, which among other highlights, allowed amateur radio operators to make two way 50 megahertz band contacts at distances of more than ten thousand kilometers!!!
Item two: Solar flux has just cross the 200 hairline, something that will combine with the equinoctial propagation conditions to provide us with very high maximum useable frequencies and rare nighttime openings during the next three to five days.
Item three: A new version of the ever-popular Arnie Coro's BROOMSTICK antenna is in the works, and the first tests show that it can really help apartment dwellers who want to use their amateur radio stations, even though they don't have space for or permission to install rooftop or yard antennas. This new version of the BROOMSTICK is also very easy to homebrew, and when connected to my PI Network antenna tuner during the first test, worked on all bands from 40 meters all the way up to 6 meters. But don't ask me why it works on 6 meters, because I really cannot explain why this antenna loads so well on 6.
Stay tuned for more radio hobby related information coming to you from Radio Havana Cuba. My sound engineer and producer is Margarita Delgado, our website URL is http://www.radiohc.org/dxers/ so don't forget to add it to your Bookmarks! Now a short musical interval and station ID coming up...
The name of the show is Dxers Unlimited; you are tuned to Radio Havana Cuba, and for late evening listening of our English Language Broadcast in Eastern North America, we have on the air our 100 kilowatts on 9550 kiloHertz from one AM to three AM Eastern Daylight Saving Time, you can listen to the late late edition of Dxers Unlimited there, the last rerun for the broadcast day, just after 0530 UTC, that is around one-thirty in the morning Eastern Daylight Time, or thirty minutes past midnight Central. The frequency again: 9550 kiloHertz, on the air with our English programming from 05 to 07 UTC.
Now item four: Recycling older computer plug-in cards, the ones that are connected to ISA slots, is a very nice way of obtaining valuable electronic components for free... Every legacy video card has at least one quartz crystal and many other useful parts; the same holds for old floppy disk and hard drive controller cards. My new regenerodyne receiver, a combination of a simple crystal controlled converter and regenerative detector uses several crystals salvaged from old ISA slot computer cards. For example, the 1.843 kiloHertz crystals not only make a nice single tube CW transmitter for 160 meters; they also provide coverage for Tropical reception with the regenerodyne, tuning from about 3.8 to 5.8 megaHertz when the regenerative detector tunes from 2 to 4 megaHertz.
I did receive several questions from Dxers Unlimited's listeners asking why use this frequency conversion set-up, and the answer is that your detector will always work within a limited frequency range, you can calibrate your dial, and calibration will not drift away... and last but not least, the overall receiver gain and stability is much better than when you connect a regenerative detector directly to the antenna. In addition, by using the Radio Frequency amplifier and mixer stages ahead of the detector, you avoid many problems that are typical of regenerative receivers when coupled directly to the antenna. By the way, and before I forget you can learn a lot more about regenerative receivers by requesting Arnie Coro's Regenerative Receiver INFO PACKAGE. Send your request to arnie@radiohc.org, and if you are not yet in cyberspace, send your request via AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
The equinox is just around the corner... in just a few hours the Autumn Equinox will occur for the Northern Hemisphere, and Down Under they will have their Spring Equinox. For all radio enthusiasts world wide the equinoctial DX season is a very important part of the year as some really very special short wave propagation conditions are now in progress and will last for about three more weeks. So, here is Arnie Coro's advice: Optimize your listening schedules just before local sunset, then again just around midnight your local time, and set your alarm clock for as early in the morning as you can. During the equinoctial DX season those are the three optimum time slots for picking up some really nice ones!
Item five: High speed computers, the ones that run their internal clocks above the 300 megaHertz, don't only work faster; they also have proven to be much quieter from the radio frequency interference point of view. Very fast clocks do not cause interference to short wave reception as the older machines did, using clock frequencies all the way from around 4 megaHertz to 33 megaHertz.
When asked by a Dxers Unlimited listener via e-mail why his primary machine did not affect his short wave reception, while his older DOS 386 running at 16 megaHertz did, I explained to him that the newer machines do not have harmonics that hit the short wave spectrum badly. But there is still one big problem operating computers and radios side by side: When you are using cathode ray tube monitors, the high-power horizontal output sawtooth waveform can make reception next to impossible; that's why it is a very good idea to use a liquid crystal display machine to interconnect to your radios.
Item six: YOU have questions and I do my best to answer them! Here is the reply to a question sent in by a long-time Dxers Unlimited's fan from California... He wants to know how big a magnetic loop antenna can be, and still work. Well amigo, according to my practical experience, the larger magnetic loops do work well, and their maximum size should not exceed about one-third of a wavelength.
A good rule of thumb is that the magnetic loop will require at least about 20 picofarads for tuning it to the lowest operating frequency that it will go. A good example of a very efficient magnetic loop antenna will soon be made available for downloading at our website; it is a 4-meter diameter, or about 13 feet, circular loop made with surplus Heliax transmission line, which can usually be obtained just for the asking from TV and FM stations' engineering departments. The Heliax line outer copper conductor is used for the antenna, and it performs very well. You can build magnetic loops as small as one meter or about 3 feet in diameter, but those will only be efficient above 14 megaHertz or so for transmitting.
And now amigos, as always at the end of the show, here is Arnie Coro's Dxers Unlimited HF PLUS 6 meters propagation update and forecast: Solar flux past 200, and going up; the A index on Monday was 33, indicating geomagnetic storm conditions caused by high speed particles from the SUN hitting the Earth's magnetosphere, and similar events are almost sure to occur during the next three to five days. Expect much higher daytime maximum useable frequencies, with the MUF hitting as high as 55 megaHertz on some North-South paths. Nighttime openings on the 17 and 15 meter bands are almost surely going to be available, and 10 meters should provide many excellent contacts all along the local daylight hours.
Send your radio hobby-related questions, signal reports and comments to arnie@radiohc.org, or via Air Mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba. I'll be on the air on 15 and 10 meters as much as possible during the excellent equinoctial propagation conditions, so look for CO2KK around 21295 or 21310 on 15 meters and 28.495 or 28.500 on 10 meters, amigos... Forget about your soldering irons for the next week or two; propagation is too good to waste!
prepared 19-Sept-2000; transmitted 21-Sept-2000 21:45
Arnie Coro CO2KK
Havana, Cuba
September 19, 2000Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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