RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, MAY 15, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos! Welcome to the mid-week edition of Dxers Unlimited. I am Arnie Coro, radio amateur CO2KK here in Havana; my sound engineer and producer is Margarita Delgado. Stand by now for about 18 minutes of all radio hobby-related information after this brief musical interval. Solar flux is very near 140 units, and Sporadic E clouds are bringing in lots of VHF DX to radio hobbyists in the Caribbean, North and Central America and Europe. I'll be back in a few seconds...
You are listening to Radio Havana Cuba, the international short wave broadcast station where you, the listener, come first...
The topic INDOOR ANTENNAS seems to have a particular magnetism for both short wave listeners and amateur radio operators who live in areas with external antenna installation restrictions. When faced with the problem of installing a better indoor antenna, many short wave listeners and radio amateurs are going, more and more, into using the so-called magnetic loop antennas. Although they are very narrow banded and do require constant retuning, they offer the most efficient indoor or balcony antenna yet available...
A Dxers Unlimited's listener in Canada was telling me recently that he has installed two indoor antennas; one is the three-foot diameter (roughly one meter) magnetic loop, and a version of my Broomstick antenna, about 5 feet or 1 and a half meters, high. He has both antennas connected via short lengths of coaxial cable to a homebrew switch, so he can select one antenna or the other at the flip of the switch. "Arnie," he tells me, "when I am listening to a powerful short wave station, I normally use the Broomstick, to which I have added three radials or counterpoise wires which are located under the rug.... When looking for weak stations, I use the magnetic loop, which is a less convenient antenna, because I have to retune it constantly, even when moving just a few kiloHertz away from the center frequency that I have the antenna tuned to..."
He then asks me if there is a way to bypass this inconvenience, to which the answer is NO. The magnetic loop's very high Q makes it impossible not to retune when you change frequency even by just a few kiloHertz. So your idea, amigo from Edmonton, Alberta, Canada, is a very good one -- using the switch to change from the wideband Broomstick to the very narrow band Magnetic Loop is giving you what could be described as the best of both worlds!!! And, by the way, you might want to go to our Dxers Unlimited website and download the file that shows how to build a very practical and easy-to-homebrew PI network antenna tuner, which does help a lot to improve reception, especially when you are using low-cost solid state short wave receivers that don't have good enough front-end selectivity... The PI network tuner also improves the performance of any long wire, dipole, or short helical antenna, and adds protection against front end overload because, after all, you are adding a tuned circuit ahead of your receiver's input!
Want to receive a Radio Havana Cuba QSL card? Just send your request to Arnie Coro, Dxers Unlimited, Radio Havana Cuba, Havana Cuba, or send e-mail to arnie@radiohc.org. Do remember to include your postal mailing address with your e-mail message, and don't forget to send a signal report, and some comments about the show -- something that is required to verify reception.
You can also subscribe to our Dxers Unlimited's mailing list, which will send to your mailbox two mailings per week, with the scripts of the show in HTML format. This is giving me the wonderful possibility of including graphics related to the topics covered on the show, something that has brought very positive feedback from those who have already subscribed... So, write this down: send an e-mail message with a blank subject line, and in the body of the message just type: subscribe dxers_l that is, the word subscribe, a space, then dxers, underscore and the letter l like in lima...
The majordomo mailing list software then will send you an automatic confirmation and the how to unsubscribe instructions... Then you will start receiving Dxers Unlimited's scripts as soon as they are posted on our website. And remember that you will have the unique opportunity of seeing some nice graphics related to the topics covered on the air!
You have questions, yes, every radio hobbyist, even the experts, have questions about some particular aspect of radio. For example, a long-time radio amateur, with more than thirty years on the air, sent the following question regarding the upswing he notices in the use of digital communications modes... Here is what he writes:
Arnie, when packet radio started a number of years ago, I was not enthusiastic about it, I thought it was just a way of moving around messages, lacking in appeal, as packet contact seldom happened between two on-line stations... Now, I find a lot of activity using the PSK31 mode, a live keyboard-to-keyboard mode that opens up a lot of interesting opportunities to make nice contacts using low power radios. Here is my question: Isn't there something in the works to make PSK31 operation possible using older computers even without a sound card?
Well amigo from California, I agree with you 100 percent!!! PSK31 keyboard-to-keyboard communications are fascinating, and with the computer skills developed by almost everyone, I see that typing is at a rather nice speed nowadays, something that was not the case many years ago with the radio teletype machines. PSK31 is very easy to implement with a modern fast computer and a sound card but, not everyone can afford one of those fast PENTIUMS, especially amateurs in third world countries... A few days ago, I learned from CO3FP, my good friend Evelio, about a new PSK31 software that makes reception possible using the simple HAMCOMM computer-to-radio interface... So, YES, now you can receive PSK31 using an older DOS operating system machine, perhaps a fast 386 or an older 33 mHz 486 -- again, in DOS mode, using this software and the HAMCOMM interface circuit. For transmitting Evelio, CO3FP, told me that he had built another little black box that linked the computer to his transceiver, allowing transmission of the PSK31 mode...
So once again, the answer to your question: YES... it is possible to receive and send PSK31 without a sound card, and I can assure you that it works, because I had a nice two-way QSO with CO3FP using the PSK31 mode on 2 the 2 meters FM getting, as the old timers in RTTY say, perfect print, although the copy, of course, was on my computer screen!!! Any questions, you just e-mail them to me at arnie@radiohc.org
This is Dxers Unlimited's mid-week edition amigos, coming to you from Havana. And yet another question for the ever-popular YOU HAVE QUESTIONS, and Arnie answers them section of Dxers Unlimited. It came from Mexico, a surprise, as I didn't expect to have people listening to me in English in Mexico! Well, this a Mexican listener from Jalapa, Veracruz who listens regularly to DXers Unlimited's Caribbean release during the late afternoon his local time, and he wants to know how to protect his small portable radio when it is connected to an external antenna. He adds, Arnie this is a part of Mexico with lots of thunderstorms, so I need to know what must be done to protect my solid state radio.
ANSWER: First things first! Connect the radio to the antenna only when you are using it. Once you finish listening, make it a habit to disconnect both the AC power source and the antenna... That's the best protection of all, and when the weather looks bad, it's cloudy and a thunderstorm may be about to start, then do not connect the radio at all. You can add a very simple back-to-back silicon high-speed diodes protection, but that will only help you with induced voltages no higher than about 30 volts or so... And modern solid state radios do not benefit at all from the classical neon bulb or special gas discharge tube protection systems....
Item five: More about recycling.... another excellent source of electronic parts that is now becoming available are the old monochrome and the 4-color and 16-color CGA and EGA computer monitors. The older ones have quite a few parts, and with the wire from the yoke coils, excellent stealth antennas can be made... So, if you happen to find an old computer monitor, just u-haul it by yourself to your shack, remove the picture tube very, very carefully, and then proceed to recyle the components for your next radio project. Disposal of the cathode ray picture tube will require advice from a local TV repair shop. Do it properly, and protect the environment...
And now amigos, just at the end of this show, as always, here is your guide to better use of the HF spectrum plus 6 meters, Arnie Coro's Dxers Unlimited's propagation update and forecast: Solar activity will be hovering from LOW to MODERATE, but it is now moving UP again. Solar flux is around 140 units, and the A index early morning on Tuesday was 12, the all-important EFFECTIVE SUNSPOT NUMBER is at a rather low figure, just barely above 90, and that takes its toll on the daytime maximum useable frequencies, which are hovering around 35 megaHertz for the best propagation paths; that is, North to South...
The daily sunspot count for Tuesday is almost 150, up by 30 from Monday... AND YES, we are seeing quite a few SPORADIC E openings here in the Northern Hemisphere... several of those openings have taken the Maximum Useable Frequency up to the FM broadcast band, and that's good news for FM band Dxers, who enjoy one of the more than 50 ways that you and I can have a good time playing with our radios, that is FM broadcast band Dxing....
For Short Wave Listeners here is our forecast: Stay away from the lower frequencies, as they are becoming noisier due to the summer season thunderstorms. Best daytime reception will be happening on the 19 meter band up to about three hours after sunrise; then the 16 and 13 meter bands will be your best options for nice, high-quality, fade-free reception.
For amateur radio operators, the 20, 17 and 15 meter bands will be offering nice DX possibilities starting at your local sunset, when ionospheric absorption will be at a minimum. May 15th is a sort of landmark propagation-wise, as from now on and until around mid-September, the summer season conditions will prevail, that meaning the very peculiar higher nighttime maximum useable frequencies!
See you at the weekend edition of Dxers Unlimited next Saturday and Sunday UTC days, and don't forget to subscribe to our Dxers Unlimited e-mail distribution list, so that if you miss our broadcast, you can always read the script sent to you in HTML format automatically, as soon as it is posted at our Dxers Unlimited website!
Arnie Coro CO2KK
Havana, Cuba
May 15, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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