RADIO HABANA CUBA
DXERS UNLIMITED
MID-WEEK EDITION
TUESDAY, April 9, 2002
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi, amigos radioaficionados around the world! Welcome to the mid-week edition of your favorite radio hobby program... Solar flux still above the 200 mark, and the planetary geomagnetic disturbance indicator was way down during the past 48 hours. But, beware as we may see class M solar flares erupting during the next several days!!! HF propagation conditions have kept the 15 meters or 21 megaHertz amateur band very active because at this moment it is the best band for Dxing during most of the day.
Item two: For those of you who are already enjoying communicating via low earth orbit satellites, good news: a new satellite is now available to operate using mode J, that means uplinking via 2 meters FM and picking up the satellite's downlink via the 70 centimeter band... More about the newly available satellite later in today's mid-week edition of Dxers Unlimited.
Item three: Lots of feedback about the treasure chest of high quality electronic components found when opening up dead MFM computer hard drives... Got some nice comments about how well preserved those parts were found to be and that practically all the components test good!!!
Item four: Cuban radio amateur Lucio CO5TL has come up with another easy-to-build single band transceiver... He says that he obtained information from many different rigs and after lots of experimentation at his Matanzas province location, he decided to use what he has described as the best circuit for each section of the transceiver. He has named it "The Nothing but the Best radio," and he promised to provide me with the complete circuit diagrams soon.... As you may see, homebrewing is alive and well among Cuban amateur radio operators. By the way, the rig is basically a double sideband transceiver for the 40 meter band, and also capable of working on CW too...
Item five: Dxers Unlimited's antenna topics section, followed by Item six, you have questions and Arnie tries to answer, and just at the end of the show, our ever-popular Arnie Coro's Dxers Unlimited HF plus 6 meters propagation update and forecast.
Margarita Delgado is my sound engineer and producer, stand by now for a brief musical interval... back with you in a few seconds...
You are listening to the mid-week edition of Dxers Unlimited, and now listen to more radio hobby-related information... Using vertically polarized antennas for operating on the 30, 20, 17,15, 12 and 10 meter bands will in some cases dramatically reduce the probability of producing interference to TV sets, but maybe not at all on FM radios, VCRs and HIFI. The fact is that horizontally polarized antennas used for transmitting cause more TVI, that is TV interference when the TV sets are receiving signals from an outdoor antenna... But, a vertical transmitting antenna mounted close to the ground can wipe out cable TV reception, FM band signals and make VCRs go on the blink, while some HIFI sets may go from Mozart or Heavy Metal to your voice calling CQ DX!!!
The reason I brought up this topic here today is that handling interference to other radio services has become nowadays an important aspect of amateur radio activities. After all, you don't want your hobby to put you in trouble with the neighbors or even your own close family members. That is why it is so important for the amateur radio operator to learn the facts about what is known as EMC or electromagnetic compatibility, the nice sounding name for the art and science of making electronic equipment work when radio frequency energy is present! The use of a vertical antenna system, when properly installed, is one of the many practical solutions that radio amateurs can try to reduce or eliminate interference produced by ham radio transmitting equipment. I have succesfully tried the vertical antenna systems approach to eliminate TV interference with the amateur radio operator's neighbors, when I continued to have problems even after installing high pass filters.
Now, amateur satellite news: AMSAT President Robin Haighton, VE3FRH, has just informed us that the satellite SaudiSat 1A is now open for Amateur Radio communications.
In a letter to VE3FRH, Turki Al-Saud announced the following: "Please announce the availability of SaudiSat 1-A (SO-41) to AMSAT members and to follow Amateur Radio operators in your region. Named from now on as OSCAR-41, the satellite has been configured for operation in the amateur service. The spacecraft will automatically enable its UHF transmitter over Saudi Arabia and the United States for approximately 20-minutes each pass.
"The spacecraft is operating in Mode-J, centered on a VHF uplink and UHF downlink of 145.850/436.775 MHz, currently configured as an analog FM voice repeater. The spacecraft will operate in this mode intermittently, as power and spacecraft experiments permit. SO-41's downlink RF power is 1-watt over both regions with left-hand circular polarization. The uplink antenna (located on top of the spacecraft) is linear in polarization."
And now here is the ANTENNA TOPICS section of Dxers Unlimited: Some antennas have really fancy names given by their designers... For example, a very popular antenna among amateur satellite operators that uses the LEOs, or Low Earth Orbit Satellites, is known as the EGGBEATER, while another new one for similar applications has received the name of the POTATO MASHER antenna. As you can guess, the names have to do with the shape of the antenna elements... Then you have of course the DISCONE, built using a top disk and a cone, the dish antennas, a common name for all antennas using parabolic reflectors and the RUBBER DUCK, used atop hand-held transceivers and scanners!!! There are also the HULA HOOP and the RHOMBIC to add two more names used to describe antennas in an easy-to-remember way!!!
Today I 'll tell you about the DELTA LOOP, an antenna that has among its advantages the fact that it can be supported from a single mast, tower or even a tall tree... DELTA LOOPS are popular among radio amateurs, but few short wave listeners have ever heard about them because in the currently available beginners' literature for SWLing, there is usually no information about the DELTA LOOP.
The most common DELTA LOOP is one wavelength of wire at the operating frequency, but soon you will find that when connected to my PI NETWORK ANTENNA TUNER, a one wavelength long DELTA LOOP will work on several bands higher in frequency than the band it was cut for. One nice DELTA LOOP design for short wave listening and ham radio operation is about 21 meters long, that is if you configure it as an equilateral triangle, each side is 7 meters long... but you can even make such a DELTA LOOP fit into a tigher horizontal space by making the vertical sides longer and the horizontal side shorter. This 21-meter overall length of wire DELTA LOOP, when fed via open wire transmission line, will let you operate on the 30, 20, 17, 15, 12 and 10 meter bands with the antenna tuner. Practical installations can be made slanting the loop so that it is not exactly vertical, and according to antenna modelling software and actual practice that improves the performance of such antennas...
Yes amigos, there are many easy-to-build antennas that will dramatically improve your short wave reception when connected to your receiver, but be aware that the cheaper radios may actually perform very poorly when a good external antenna system is connected to them.... The reason for this paradox is that those EL CHEAPO, Saturday night special and catalog short wave receivers do not have the input circuit elements required to handle the much stronger signals delivered by the big external antenna, so they will perform more or less well with their own little telescopic whip, and show themselves very allergic to big external antennas!!! By the way this answers a question sent in by a Canadian listener who wanted to know why his radio showed a much degraded performance when he connected it to a recently built TTFD or Tilted Terminated Folded Dipole.....
Si amigos, our wonderful radio hobby has many different ways that you and I can enjoy it... from talking to your friends via the local FM two meter or 70 centimeter band repeaters to listening to nice music from seven or eight thousand kilometers away, as I am doing right now as I type the script of the show...
It happens that Radio Exterior de Espana has an excellent musical program on 21700 kiloHertz just after noon local time here in Havana, when I usually start writing the final version of the script for Dxers Unlimited. Listening to the nice audio using my big loudspeakers fed from the almost-40-year-old R403 Chinese vacuum tube receiver has brought very interesting comments from visitors who thought that short wave listening was only picking up voice transmissions with lots of noise...
The 13 meter band is particularly ideal for short wave music broadcasts, as it is not as crowded as the lower frequency bands. The typical high quality short wave high power transmitter, when properly maintained, can provide a frequency response well past the five kiloHertz accepted audio bandwidth... So, I am afraid that some transmitter engineers will probably run the high frequency cut off filters at around 6.4 kiloHertz or so.... The just-mentioned Radio Exterior de Espana musical program is an excellent example of the nice reception that may be achieved when proper frequencies are used and the transmitters are well kept and well modulated...
Si amigos, short wave listening can also provide you with many hours of nice music, yet another way of enjoying our wonderful hobby in a very special way, as some of the music heard via short wave is simply not available from any other source!!! Try picking up some of the Brazilian Tropical Band stations that operate on the 60 meter band, too!
And now, as always at the end of the show, here is Arnie Coro's Dxers Unlimited's HF plus 6 meters propagation update and forecast.... Solar flux still way up, higher that what scientists were expecting for this month of the solar cycle... And higher solar flux means higher maximum useable frequencies, so you will find the bands from 14 megahertz to 21 megaHertz open almost 24 hours, while the segment of the HF spectrum from 21 to 35 megaHertz continues to provide reception of DX signals during your local daylight hours... 6 meter band openings continue, and many radio amateurs who are new to the MAGIC 6 meter band are adding new countries to their logs... We may see more solar flares from today until the weekend... so this may bring sudden radio storms if the flares are of the M or X class... Equinoctial propagation is still here, something that is really nice for enjoying the typical just around local sunset propagation enhacement...
See you at the weekend edition of Dxers Unlimited amigos, and don't forget to send your signal reports and comments about the show, and your radio hobby related questions to arnie@radiohc.org or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, Havana, Cuba.
Prepared 09-Apr-2002; received by NY Transfer News 11-Apr-2002
Arnie Coro CO2KK
Havana, Cuba
April 9, 2002Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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