RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, JANUARY 12, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados around the world -- and in space because, yes, we do have radio amateurs in space, too!!! Welcome to the weekend edition of Dxers Unlimited, your favorite listener-oriented radio hobby program. I am Arnie Coro, radio amateur CO2KK, your friend here in Havana and host of this twice-weekly show, our modest contribution to the promotion and development of this wonderful hobby you and I enjoy... RADIO!!!
And here is item one: A polar cap absorption event has disrupted propagation paths via the poles, a satellite proton event was also in progress, and the daily geomagnetic planetary disturbance indicator went up Friday to 20 units, as the Earth's magnetosphere received the impact of yet another coronal mass ejection caused by a solar flare.... BUT, it seems like the ionosphere is recovering and at around 16 hours UTC Saturday, eleven o'clock in the morning local time in Havana, a quick scan of the upper segment of the short wave spectrum showed good signal levels and the 12 and 10 meters amateur bands fully open.
Item two: Lots of e-mail keeps coming in to arnie@radiohc.org regarding the homebrewing of radio receivers, all the way from the simplest to now some rather complex sets been built by more advanced hobbyists... sure, we all enjoy that special moment when the just-finished radio we have built is powered up for the first time...
Wednesday I had the experience once again in my life, of flipping the switch of a new homebrew receiver, and you know what happened? Well, maybe I'll leave tht for a little later, because it was a lot of fun and I'd like to share it with you all...
Item three: An e-mail received here about dismantling an old VCR for recycling its parts transmitted that special joy of those that want to keep spaceship Earth shipshape!!! Scot, a regular listener of Dxers Unlimited, describes the treasure chest of electronic and mechanical parts that he saved from the dumpster by recycling that old VCR machine.... Si amigos, yes my friends, oui mes amis... don't throw away any piece of electronic gear.... set aside some of your spare time, especially when you are a little tired, to take it apart. Recycling VCR's, TV sets, FAX machines, answering machines, old radios, computers, monitors etc. etc. is a very relaxing thing to do indeed, as it certainly does not require the degree of mental concentration demanded when you are assembling a new piece of equipment or trying to repair something!!!
Item four: You have questions and Arnie tries to answer them, and as always at the end of the show, our exclusive and not copyrighted in the public domain Arnie Coro's HF plus 6 meters propagation update and forecast...
Stay tuned, this is your favorite all radio hobby program, entirely, absolutely devoted to RADIO in its more than 60 ways you can enjoy it!!!
This is Radio Havana Cuba, the name of the show is Dxers Unlimited, our website URL for Dxers Unlimited is http://www.radiohc.org/dxers/, and you can send your signal reports and comments about the show via e-mail to arnie@radiohc.org and if not yet in Cyberspace, send a postcard to me; mail to: Arnie Coro, Radio Havana Cuba, Havana, Cuba....
Now here is item two in detail: one fascinating aspect of our hobby is homebrewing the equipment we use, or at least some of it.... Yes you may go the store, and buy a nice short wave receiver, install an antenna and start listening to the world in a few hours time... but, there is nothing that can be compared with the pleasure of listening to a homebrew radio, although sometimes what one builds does not work from the very first test!!! Here is a story I am sure many of you have seen in real life...
Wednesday I was giving the finishing touches to yet another homebrew receiver... this one was built in such a way that it could help me teach the basic principles of radio and electronics to members of the Plaza and Playa radio clubs who visit me on Sundays mornings for the basic course that will lead them to obtaining the amateur radio license. This particular radio was designed as a hybrid, something I did on purpose to familiarize my students with different technologies...
The radio uses diodes, transistors and simple integrated circuits, plus vacuum tubes. The tubes were included because they are locally plentiful at practically no cost by recycling TV sets, and they are certainly very rugged and long-lasting active devices...
Well, my radio and its separate power supply were ready for testing and as soon as the last soldering was done, I then very carefully checked all connections, and then plugged the power supply to the 115 volts 60 cycles power line.... Of course I used my standard safety procedures, that include never firing up a new set without connecting it via a current-limiting 100-watt light bulb... If something is terribly wrong with what you are testing, instead of obtaining some nasty smoke from a burned-out part, you simply receive a warning in the form of a fully lighted 100 watt bulb!!! In this case the HYBRID receiver did just that after about a minute of warming-up time, indicating that somewhere in its circuit something was wrong!!!
It took me about half an hour to find that there was a wiring mistake, then I unsoldered the wrongly soldered connection, placed it in the right place, and tried again... Well, what a relief!!! The background hissing sound from the eight-inch loudspeaker told me that at least I had the audio stages working... Then my low-cost easy-to-make-yourself active signal tracer was connected to the center of the volume control, and SURE!!! a one kilohertz square wave produced ear-shattering volume....
By the way, this is the proper procedure when you want to repair a radio, always start BACKWARDS, from the loudspeaker back to the antenna!!!! Well, after about an hour, and just before Olguita, my wife called, for supper, my new homebrew radio was picking up short wave signals on the ever popular 49 meter international broadcast band!!!
I still have to work a little more on this project to finish building two more sets of plug-in coils, and give the final touches to the cosmetics of the radio.... BUT, it is now ready for its first encounter with the students around 9:30 a.m. Sunday morning, when they will be coming in for their amateur license test class... This radio was built with special care, so that measurements could be easily made, and the circuit may be followed visually as well as from an electronic point of view, something that has made it an oversized radio by all standards.
AH, before I forget, it is a dual conversion receiver that has three different detectors, a regenerative detector, a standard diode AM envelope detector and a product detector for Single Side Band and CW, so it can be used to demonstrate how different circuits perform. Of course the regenerative detector can be used for AM, CW and SSB, depending of the setting of the regeneration control. This is a nice radio, capable of tuning from the low end of the AM broadcast band up to the 21 megaHertz or 13 meters international short wave broadcast band, by changing plug in coils that are very easy to build and to experiment with them...
This NEW HYBRID RECEIVER, Arnie Coro's NHR-ONE, will soon be made available at our Dxers Unlimited website so that Dxers Unlimited's listeners around the world may see the circuit diagrams and perhaps become interested in duplicating the NHR-ONE to use it as a second experimental receiver that is always so useful in one's shack!!!
This is the weekend edition of Dxers Unlimited the effective sunspot number is at a nice and high 185 units, keeping those higher frequencies open for DX many hours during the next several days...
Here is item four, our popular "you have questions and Arnie tries to answer them:" This question from a listener in Florida, USA:
Arnie, you seem to enjoy restoring and even building vacuum tube equipment a lot, shouldn't you warn your listeners about the dangers of the high voltages used by vacuum tubes???Well amigo Stewart, YES, ABSOLUTELY, and I do thank you very much for your observation... IT IS VITALLY IMPORTANT that anyone using voltages higher than 6 volts DC use extreme care when doing any work....Signed, Stewart from Florida,
a regular listener of your 6000 kiloHertz frequency...
YES, you heard it right, I am talking about 6 volts DC or higher, as there are reports of people severely affected and even dying when receiving an electric shock from a 12 volt car battery!!! YOU should learn all the safety procedures regarding the handling of electric circuits, and all your work must always be done when your mind is in a proper state of alert... As a matter of fact, one of the main causes of electrical accidents is that persons were working when very tired, or sleepy... So, amigo Stewart, here is the warning about working with electricity, not only with the higher voltages used by vacuum tube circuits, that, of course do require a lot of extra care, and procedures such as discharging to ground the power supply capacitors before attempting to work on the equipment!!
And now as always at the end of Dxers Unlimited... ready to copy... Here is Arnie Coro's exclusive and not copyrighted HF plus 6 meters propagation update and forecast amigos... Solar flux is MOVING UP, and I did make a mistake in my last mid week edition when I wanted to say that the solar sunspot count would reach a minimum of around 150 for this solar rotation, I said that the solar flux would reach a minimum of 150, something that was obviously wrong, as the daily solar flux number was to stay at much higher levels during the actual minimum of the 27 day cycle...
As expected during the declining phase of any solar cycle, we are seeing more solar flares than during the ascending phase, and that is perfectly normal. But again, we are now sure that cycle 23 had not one, but two peaks of activity, something that led to the most fantastic 6 meter amateur band propagation conditions since 1957 and 1958 when record breaking cycle 19 reached a maximum never before recorded... The year 2002 should see a very slow decline in solar activity, and I can assure you that the upcoming SPRING EQUINOX DX season this year is going to be another outstanding period of excellent short wave propagation...
Ah, and before I forget, propagation conditions should be returning back to normal by Monday, with yet another period of several days of very high maximum useable frequencies... See you on 10 meters, look for CO2KK, my amateur radio station on or near 28.500 when the band is open and let's have a nice two-way QSO!!!
Prepared Jan-12-2002; received by NY Transfer News Jan-14-2002, 09:32 EST
Arnie Coro CO2KK
Havana, Cuba
January 12, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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