RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, MARCH 26, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados! This is the mid-week edition of your favorite radio hobby program, Dxers Unlimited with Arnie Coro. Welcome and stay with me for the next 17 minutes...
Here is item one: Solar activity now moving down, and this will, paradoxically, going to improve the HF propagation conditions during the next seven to ten days IF, and yes, there is an IF, no new solar active regions become active. Solar flux is hovering at around 170 units, and the equinoctial propagation conditions will provide many nice opportunities to add new stations to your logs...
Item two: Had a nice talk with CO2DC, one of Cuba's most experienced radio amateurs, about the TTFD antenna.. He said that his latest version of the TTFD, equipped with a special balun provided excellent performance from 40 meters all the way up to the 10 meter band, while the standing wave ratio stayed below 2 to 1 all along the available bandwidth... CO2DC's TTFD or tilted terminated folded dipole version is 20 meters long, so you can replace your 40 meter band dipole with this one and enjoy a broadband performance at the cost of less than 3 dB loss on the 40 meter band, and with a significant advantage from 10 megaHertz and UP!!!
Item three: Earth moon Earth radio amateur contacts using a rather new software originally intended for meteor scatter work is making headlines at the world's most popular ham radio websites...
Item four: PSK31, the super energy efficient keyboard to keyboard communications mode is becoming more and more popular, especially among city dwellers... Five watts into a half wave dipole on 20 meters is all it takes to make lots of nice two way contacts using the PSK31 mode...
Item five: You have questions, and Arnie tries to answer them... one of the most popular sections of Dxers Unlimited will be here again today, answering questions sent in by listeners like you that want to learn more about this wonderful hobby you and I enjoy so much: RADIO. And as always at the end of the show, get ready to tape or take notes, as I will provide you with the most up to date HF plus 6 meters propagation update and forecast. Stay tuned for more radio hobby related information, coming to you from Havana, Margarita Delgado is my sound engineer and producer here at RHC studio 7, I am Arnie Coro back in a few seconds...
This is the mid-week edition of Dxers Unlimited, amigos, and here is our popular you have questions and Arnie tries to answer them, and of course, if I can't, then there are a lot of people that I can ask about your question too...
Here is today's first question: Arnie I have heard you talking about the equinoctial propagation conditions and how they do improve worldwide HF propagation... My question, does this apply to the 6 meter amateur band too? Signed, Canadian 6 meter enthusiast from Toronto
Well amigo, sure! Equinoctial propagation conditions that happen twice yearly when the Earth is receiving almost exactly the same amount of sunshine on both hemispheres do produce some very interesting effects on the region of the radio spectrum from 25 to 55 megaHertz, as a matter of fact, at this time of the year TRANS EQUATORIAL PROPAGATION, or TEP, shows a marked peak. And TEP is particularly noticeable on 6 meters of course, and even on the 144 megaHertz or two meter amateur band too... FM band Dxers in the Caribbean are able to pick up TEP signals of FM broadcast stations as far south as the southern tip of Argentina and Chile.
One very interesting fact about TEP propagation is that it extends well after one's local sunset, something that keeps puzzling scientists!!!! So, if you happen to own one of those new HF plus 6 meters transceivers, by all means, install even a simple two element wire YAGI for 6 meters and start monitoring the band. At this time of the year, the spring equinoctial DX season here where I am in the northern hemisphere, you simply point your antenna to the South and monitor 6 meters by scanning from 50.000 to 50.200 for any signs of DX, including, of course the many propagation beacons now on the air.
Now here is today's second question: Arnie, I have the opportunity of buying a kit from a friend, but I am not sure if I can build it or not, because it is a kit that uses SMD parts, surface mounted devices that are very small and difficult to handle...
Well amigo, I guess you already have answered this all by yourself... but let me ratify that you should stay away from kits that use surface-mounted devices or SMDs IF your are not already well trained in using those ultra-small electronic components and have a very good eyesight, aided, as you might expect, with a special lamp and large sized magnifying glass.... Some new kits are coming with partially assembled boards, where the SMD devices are already properly mounted and those are of course OK, as you are only asked to solder standard electronic components and the connections to the board or boards supplied by the kit manufacturer with the SMD devices already in place... Also, follow Arnie Coro's advice and don't attempt to build a very sophisticated kit as your first one, amigo!!! Choose a simple one as your first kit assembly project!
You are listening to Radio Havana Cuba, the name of the show is Dxers Unlimited, and yes we do QSL, we do verify reception reports, absolutely free of charge, as fromt the very first day that we went on the air almost 41years ago now, we stated a policy of 100 percent QSL station... so, start your QSL collection today, send your signal report, even a very simple one will do, add some comments about the show, and do include your postal return address. Send your QSL request to arnie@radiohc.org or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Now more radio hobby related know-how: Medium wave, AM broadcast band DXing is an aspect of the radio hobby that everyone seems to enjoy at one time or another. One of my favorite AM broadcast band Dxing radios is a TRF, or tuned radio frequency receiver I built many years ago, that uses just two penlight cells for power...
The TRF, or tuned radio frequency simple receiver, uses an FET, a field effect transistor as the RF amplifier, with variable regeneration to increase both gain and selectivity, feeding a dual diode detector which in turn delivers the audio to a two stage high gain bipolar transistor audio amplifier. The little radio uses a standard walkman type headphones and provides amazing nightime DX reception of stations up to two thousand miles away from Havana... Although this spring equinoctial DX season so far has not proven to be very good for AM broadcast band DX due to solar disturbances and high atmospheric noise levels, the little TRF receiver has picked up some nice DX from Colombia, Jamaica, the USA, Mexico and Haiti...
The secret behind this simple circuit -- actually, the two secrets of its high performance -- are the use of a very large sized ferrite rod antenna, and how the Field Effect Transistor Radio Frequency Amplifier stage can be taken to very near the point of oscillation, providing a lot of gain and a marked increase in selectivity... Of course this is a simple receiver, so don't expect the performance of a more sophisticated set; nevertheless, it is a nice weekend project that you can build yourself at low cost and with rather easy-to-find parts.
If you want to learn more about the TRF DASH 3, my favorite solid state AM broadcast band receiver,just send an e-mail to arnie@radiohc.org or if not yet in cyberspace, send an AIRMAIL postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba -- and don't forget to include your postal return mailing address...
The TRF DASH 3 circuit description file is yours just for the asking, and I can assure you that it is a very popular project for kids, as the little radio can be assembled by a child under your supervision. Once completed, the TRF DASH 3 will be a very handy addition to your emergency preparedness kit, as it would provide reception of AM stations for several hundred hours from a pair of alkaline penlight cells...
TV DX: Tropo DX season is about to start for those of us located South of the 40th parallel; in fact, it's almost already in progress. The tropospheric DX season provides some excellent opportunities to add new TV stations to your logs, and those of you already equipped with the new digital TV receivers will be able to pick many of the new digital TV stations now on the air in the USA and Canada. By the way, I have been told by several TV Dxing fans that the digital TV signals on the UHF channels seem to have a very peculiar behavior when fading is present; in other words, the digital TV DX signals just vanish when the signal level is below a certain threshold, something that does not happen with the standard analog TV.
The TV DX tropo spring season usually lasts until the real summer-type weather sets in. Here in the Western Caribbean, the season lasts usually until mid-May, when the rainy season starts... Weather patterns that lead to tropo DX are very easy to recognize, so clip your weather maps on a daily basis, paste them into a scrapbook and write down the propagation conditions that you found for that day... Soon you will learn, all by yourself, the link between certain weather patterns and VHF-UHF Tropo DX...
Ah... before I forget, let me answer another question sent in by a listener from Canada! He wants to know where he can find more Cuban radio amateurs, because he is trying to obtain the CUBA DIPLOMA AWARD, issued by the Cuban Federation of Radio Amateurs... Well amigo from Montreal, here is my advice, for the details of all the CUBAN AWARDS, visit the Cuban Federation of Radio Amateurs WEBSITE, at the following URL: [the URL was not supplied in the script we received. We'll insert it here when we track it down. -- NY Transfer].
There you can also learn how to become a member of the CUBAN DX GROUP, and regarding your question, the most popular ham band here in Cuba is 40 meters, with lots of stations active both on CW and SSB, and some also active on the digital modes. The reason for this extreme popularity of the 40 meter band here is that homebrew equipment can be easily built and propagation conditions on the 7 megaHertz or 40 meter band during the daytime are ideal for covering the whole Cuban archipelago... While during the evenings even low power 5 to 10 watt stations on CW can work a lot of DX.
And now amigos, as always at the end of the show, here is Arnie Coro's Dxers Unlimited's HF propagation update and forecast: Solar flux is hovering near 170 units and moving slowly down, solar activity is expected also to take a downward turn, making HF propagation conditions better than during the last few days when the Earth received several impacts from coronal mass ejections. Spring equinoctial propagation conditions are now in full swing, but noise levels from thunderstorm activity is higher than usual for this time of the year. The bands between 14 and 22 megaHertz are going to remain open much longer than during the winter months, so monitor them for nice DX even late evening your local time...
Send your signal reports and comments to arnie@radiohc.org, or via AIRMAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Arnie Coro CO2KK
Havana, Cuba
March 26, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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