RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, APRIL 2, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados! Welcome to the mid-week edition of Dxers Unlimited. I am Arnie Coro, your friend in Havana and host of this twice-weekly radio hobby program coming to you from Havana. Here is the menu for today:
Solar activity went up during the weekend and this rotation reached a solar flux index that went slightly above the 200 units mark... At the same time the speed of the solar wind went up to more than 700 kilometers per second, yes you heard that right, seven hundred kilometers per SECOND, and although the number of particles reaching the Earth's magnetosphere was small, the high speed solar wind did spoil a bit the HF propagation conditions especially on Sunday.... Now scientists think that the most interesting feature of the Sun is a recurrent coronal hole that has survived several solar rotations, an unusual event by all standards...
Item two: More about amateur satellites and how they continue to provide very interesting challenges to the hobbyists...
Item three: Learning about electronic components and how they behave is essential if you want to assemble kits or homebrew ham radio equipment... Today I will give you a glance about one of the most critical electronic components that go by the name of electrolytic capacitors!
Item four: You have questions and Arnie tries to answer them, amigos... today I will answer a question sent by a listener in Nicaragua regarding what to do when the AC supply is unstable, in other words, when the power line voltage fluctuates wildly... Of course, what he wants to know is what to do with his radios so that they will not be damaged...
Then, as always when I am here in Havana, at the end of the show listen to Arnie Coro's Dxers Unlimited HF plus 6 meters propagation update and forecast...
I hope that you enjoy the next seventeen minutes of air time and yes I do expect to receive soon your comments about the program via e-mail, send them to arnie@radiohc.org or VIA AIRMAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba...
My sound engineer and producer is Margarita Delgado who had a nice weekend celebrating her birthday and wants to thank all Dxers Unlimited's listeners who sent her congratulations... We are here at studio 7, and we will be back with you in just a few seconds...
You are listening to the mid week-edition of Dxers Unlimited, your favorite listener-oriented radio hobby program coming to you from Radio Havana Cuba...
Now here is item two: Amateur radio satellites do include a very special one, a manned spacecraft: the ISS or International Space Station that is equipped so far with VHF equipment, and soon will have HF band radios too... At this moment ISS is the only manned space vehicle, but in the not too distant future other manned spacecraft may be launched....
In the meantime there are several amateur radio satellites in orbit, providing some very interesting communications possibilities. Among them are the FM repeater satellites that operate using a 2 meter band uplink and a 70 cm downlink, making possible two way contacts using even dual-band hand-held FM transceivers equipped with a simple hand-held antenna... YES! You can start monitoring the FM ham satellites with a standard scanner that will tune up to the UHF 70 centimeter band... The most powerful of those birds is UO14, a satellite that was designed by the University of Surrey for another application and that was transferred to the amateur radio service at the end of its primary application's useful life, in a very nice gesture from its owners. UO14 can be heard easily even with a rubber duck antenna attached to the scanner's antenna connector...
Program the following frequencies: 435.070, 435.075 and 435.080, for the beginning of the pass, the center of the pass and the end... again 435.070, 435.075, and 435.080, that's of course the UHF 70 centimeter amateur band... Then you will want to download any of the freeware satellite orbital prediction programs, feed the Keplerian elements to the program, run it, and learn when the UO14 will be near your location... It sounds a bit complicated, I agree, but once you learn how to do it, it's a simple routine.
The more complex ham satellites like the AO10 and AO40 do require special antennas and equipment that is much more expensive. AO40, while still in orbit, has a very limited operating capability as it was damaged by an explosion that destroyed many of its features. Nevertheless AO40 is operational using a 70 cm band uplink and a 13 cm band downlink, the only downlink that has survived so far... As you can easily guess, a two thousand four hundred megaHertz band receiver and antenna system is not something that is easily found or built, so this is limiting the use of the most sophisticated amateur satellite ever built.
There are several well written books that deal with this challenging and interest aspect of the radio hobby, so you may want to run a search for more information about both amateur and weather satellites on the World Wide Web amigos!!!
This is the mid-week edition of Dxers Unlimited, solar flux is still high enough to support F2 propagation on frequencies well above 30 megaHertz, and YES, the 6 meter band is opening on a daily basis via Trans equatorial propagation...
Item three: Electrolytic capacitors... are one of the most unreliable components that form part of electronic equipment. Electrolytics do age badly and loose capacitance sharply if operated at high temperatures... Electrolytics are also prone to catastrophic failures and they can even explode under certain operating conditions, causing a lot of damage to electronic equipment. That's why you should always operate your equipment with the best possible cooling, and never obstruct ventilation holes. Electrolytic capacitors sometimes also fail in the OPEN CIRCUIT MODE, giving way to some characteristic faults that are not hard to find, especially in audio equipment or the audio section of other equipment...
Modern electrolytics are more reliable than those built even only 10 years ago, and here is one important bit of advice from your friend Arnie Coro: If you ever start playing with vacuum tube equipment, by all means, remove and replace ALL THE ELECTROLYTICS when you start to restore tube rigs... It will save you a lot of time and will surely save other components too, as an electrolytic capacitor failure may start a chain reaction that could destroy even the whole radio... Here in my workshop, I apply a policy that has given me very good results... Whenever a receiver, transceiver, audio amplifier, VCR, any electronic equipment reaches the workbench, one of the first things I do is to carefully inspect all the electrolytic capacitors for any signs of wear or leaks... And even if it takes more time, and I have to look around for the replacement capacitors, it has proved to be a very good policy to follow... Si amigos, yes my friends, time spent replacing old electrolytic capacitors can mean the difference between a radio that will live many years and one that has to be taken apart to save some parts after a catastrophic failure!!!
A listener in Nicaragua sent this very interesting question. He wants to know what to do when the AC power line voltage fluctuates a lot... Well amigo, if you happen to own a solid state radio, by all means buy a gelled electrolyte battery. Then buy a high quality automatic battery charger, and simply operate your radio from the battery all the time. By doing this, you will save your radio from possible irreversible damages that can happen when the AC power line voltage changes up and down abruptly... If you have a small portable short wave receiver, DO NOT -- and I repeat, DO NOT -- operate it using the wall wart transformer power supply. Buy two sets of nickel cadmium or nickel hydride rechargeable batteries and a SLOW CHARGER, and never -- I repeat this -- never operate your solid state portable or table top receiver from the unstable power line; you may find yourself with a receiver damaged beyond repair, amigo!!!
This is Radio Havana Cuba, the name of the show is Dxers Unlimited amigos, we are on the air twice weekly, Tuesdays and Wednesdays UTC days and Saturdays and Sundays UTC days and now here is item five: A regular Dxers Unlimited's listener was puzzled by an intermittent noise that was spoiling his short wave reception. He asked me via e-mail if I could help to find the source, and we started an exchange of e-mail messages that lasted for two weeks, until he found out that his beautiful tropical fish mini-aquarium's thermostat was the source of the terrible noise that was making short wave reception impossible. The thermostat that kept the water temperature at the required level for the tropical fish, had operated for several years, and the contacts that make and break the power to the submerged heater were damaged... Replacing the thermostat with a new one solved the problem, and he is now picking up many new tropical band stations that the thermostat's poor operation was wiping out!!!
So, whenever you have a radio frequency interference problem or RFI problem, look around for all possible sources... this listener wrote that he never thought that his tropical fish tank thermostat could generate as much noise as it did!!!
And now, amigos, as always at the end of the show, here is Arnie Coro's HF plus 6 meters propagation update and forecast... Solar activity seems to have peaked for this solar rotation on Monday, but as always, it is impossible to forecast when a new sunspot active region will come out of nowhere!!! Solar flux is now going to slowly move down from the 205 units peak for the next ten to fourteen days... And yes, equinoctial propagation conditions will continue and as the solar flux moves down, we may actually see better HF conditions!!!
See you at the weekend edition of the program next Saturday and Sunday UTC days, amigos!
Arnie Coro CO2KK
Havana, Cuba
April 2, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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