DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, MAY 8, 2001
By Arnie Coro CO2KK
Send your comments, questions and ideas to: arnie@radiohc.org
Hi amigos! Nice to share with you the next eighteen
minutes of air time, and also have the opportunity of you reading the scripts on our Dxers Unlimited website, too! I am
Arnie Coro radio amateur CO2KK, your friend here in Havana, and here is
our menu for today...
Item one: Solar activity moving down, as expected, and yes -- the stream of particles from the coronal hole did sent the A index, the daily planetary geomagnetic disturbance indicator up to 20 units on Monday... With a solar flux and an expanding ionosphere due to seasonal variations, say goodbye now to everyday F2 DX contacts on 10 meters for the moment.
Item two: Sporadic E DX season now in full swing, Tuesday morning my new ATEC Cuban-built TV set was bringing in several TV channel 2 and channel 3 stations, but I could only get a full identification of Chicago's TV 2 at 15 hours UTC....
By the way, the ATEC, which stands for Advance Technology Cuban-built TV set, has proven to be very sensitive and has an excellent FM audio detector, too...
Item three: The old single wire antenna dates back to the early days of ham radio, but it has a certain magic that makes it work well. The W3EDP 84-foot long, that is 24.6 meters, single wire, with a single 17foot long, that is 5.18 meters long, counterpoise, continues to amaze everyone who tests it... More about the "classic" W3EDP long wire ham radio antenna later in today's midweek edition of your favorite radio hobby program on short wave and on the WEB...
This is Dxers Unlimited, Margarita Delgado is my sound engineer and producer, I am Arnie Coro in Havana... stay with us, I'll be back in a few seconds...
Yes amigos, send your QSL requests, your comments about the show and ANY radio hobby related questions to arnie@radiohc.org and via AIR MAIL, a postcard will do, send to Arnie Coro, Radio Havana Cuba, Havana, Cuba...
Now here is Item three in detail... For years, both amateur radio operators and professional telecommunications engineers have used the W3EDP antenna for ham radio stations operating between 3.5 and 30 megaHertz... the 84-foot long wire that is 25.6 meters, starting right from the station's antenna tuner and going out into whatever space is available, has proven to be a reasonably good antenna system. No, don't be mistaken, amigo... it won't be as efficient as a full-size dipole for the 80 meter band fed with open wire transmission line, it won't match a half-wave dipole for each band you want to use, but the W3EDP is so easy to install and get running... that's why I always recommend it to everyone. As a matter of fact, my advice is that if you are an amateur radio operator and have enough space for a W3EDP long wire, by all means install one and bring it into the shack, so that you may switch between the W3EDP long wire and any other antennas you may have installed at your station.
Adding the counterpoise originally recommended by W3EDP is an easy job, just a wire 5.18 meters long, running from the antenna tuner's ground connection -- that is about 17 feet, which can be lying on the floor, under the rug if your shack has one, or along the wall -- will work. I prefer to use a better counterpoise system, consisting of quarter wavelength radials for at least 40, 20 and 10 meters, although I have found that usually the 40 meter ground radial takes care of any possible Radio Frequency floating around in the shack problem... Again, here is a simple, easy-to-install antenna system... just 84 feet or 25.6 meters long, it does not need to be installed in a straight line ... fed from a simple PI network antenna tuner that you can also build yourself.
The W3EDP, from the very early days of amateur radio is still alive and well, and is becoming very popular nowadays among those who are forced to install stealth antennas due to building code restrictions and condominium rules... A very thin wire, dropping down from a window or balcony to a nearby tree or lampost, if made "a la W3EDP" with the magic 84-foot 25.6 meter length, has shown to be THE WAY TO GO for many city dwellers.... By the way, you can use a regular T match type commercial antenna tuner, too but my advice is to build a much better one using a PI network...
OK, have any doubts about the W3EDP magic single wire antenna? Well, just send me an e-mail and I'll answer it real fast... send mail to arnie@radiohc.org or via AIR MAIL send your postcard or letter to Arnie Coro, Radio Havana Cuba, Havana, Cuba....
You are listening to Radio Havana Cuba, forty years on the air at your service. The name of the show is Dxers Unlimited.... and here is Item four: the very popular among Dxers Unlimited's worldwide audience, "you have questions and Arnie answers them..." Here is today's question... it came from a listener in California, USA:
Arnie, I followed your advice, took my amateur license test, and I am now on the air with a nice little 2 meter band FM transceiver, a handie talkie.... I can access several local area repeaters, and one that is really far away at a mountaintop location... Here is my question: How can I improve my direct, or as hams say, simplex channel coverage with this handie talkie?
Well amigo, it seems to be obvious from your question that you are having a good time on the 2 meter band, but that you do want to talk to some local friends without having to go through the repeaters... In order to do this, you will need to add to your hand held radio station an external gain antenna, and if possible, an external power amplifier, popularly known among hams as a "brick" due to its heat dissipating structure resembling an aluminium brick. My advice is that you start experimenting by adding a simple external omnidirectional antenna, that is, an antenna that radiates equally in all directions...
By replacing the little rubber duck antenna that you are using now with, for example, an easy-to-build J pole type antennna, both your reception and transmission will improve a lot... Here is a real life example, drawn from actual measurements made here. I replaced the rubber ducky on my Yaesu FT411E 2 meter FM transceiver with a J pole made from 450 ohm window line, and then measured the field intensity of the transmitted signal with both antennas... Well, you know, it's simply amazing... The calculated efffective radiated power went up from an estimated less than 1 watt to almost 10 watts and, as expected, the receiver's ability to pick up stations also went up considerably. The 450 ohm window line J pole is very easy to make, and you can hang it from any convenient support. I also made one using standard TV 300 ohm twin lead line, and obtained similar results. Both antennas were fed using RG58U 50 ohm coaxial cable, and matched to the feedline with a VHF Standing Wave Ratio meter. I was able to achieve an SWR of about 1.3 to 1, which is perfectly reasonable to operate the handie talkie.
Another advantage gained by replacing the handie talkie's rubber duck antenna with the flexible J pole was that reception improved dramatically, too... Installing the flexible TV 300 ohm ribbon line J pole on my balcony rail, using a length of PVC pipe as a support mast, extends the range of the 5 watt output handie talkie by many miles, making possible direct, simplex channel contacts with stations that could not even be heard with the rubber ducky helically wound short vertical antenna. So, amigo from California, I already sent you the diagrams for building the flexible J pole, and also another set of diagrams for building a permanent J pole made from copper plumbers pipe...
And for all of you listening and wanting to obtain the J pole 2 meter antennas info package, it is very easy to get it... just send an e-mail to arnie@radiohc.org and in the body of the message type "2 meter J pole info package!" Via Air Mail, send a post card with your request for the 2 meter band J pole antennas info package to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
This is the mid-week edition of Dxers Unlimited, your favorite radio hobby show... and here is Item five: Another source of low-cost electronic components found... one of my basic electronics course students at the Nuevo Vedado Youth Computer and Electronics Club brought it to my attention on Monday... Dead photocopying machines have a large number of electronic components that can be recycled very effectively. My student's uncle works fixing photocopiers, and he has already provided his nephew with several circuit boards full of very high quality parts that only need to be desoldered. Among the goodies, I saw power diodes, a nice low voltage power transformer, power transistors and high quality electrolytic capacitors, plus many resistors and small signal transistors and integrated circuits, so add this new source to your list: non-working photocopiers that may be gathering dust in a closet are an excellent source of electronic parts for your radio hobby experiments!
And now amigos, as always at the end of the show, here is Arnie Coro's HF propagation update and forecast: Solar activity is moving DOWN, and it has just passed the critical 150 solar flux unit mark, meaning that the possibilities of 10 meter band F2 layer propagation will be practically disappearing until the next solar rotation. Sporadic E clouds are now appearing everywhere from about 20 degrees North all the way up to about 50 degrees North, as the summer Sporadic E season continues to develop. Watch for signs of E skip by monitoring the lowest frequency TV channel at your location.
For short wave listeners, nighttime reception will be best in the range from 9 to 16 megaHertz, while during local daylight hours best reception will be available between 15 and 22 megaHertz... Amateur radio low power or QRP operators should try using the 21 megaHertz or 15 meter band, which will provide the lowest ionospheric absorption during the next several days.
See you at the weekend edition of Dxers Unlimited, amigos, and do remember that your e-mails and letters are what make the difference -- yes, because Dxers Unlimited is a different radio hobby program thanks to YOU!
Arnie Coro CO2KK
Havana, Cuba
May 8, 2001
Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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