RADIO HABANA CUBA
DXERS UNLIMITED
WEEKEND EDITION
SATURDAY, JUNE 09, 2001
By Arnie Coro CO2KKSend your comments, questions and ideas to: arnie@radiohc.org
Hi amigos! You are now listening to the weekend edition of your favorite radio hobby program... I am Arnie Coro, radio amateur CO2KK, your host here for the next almost eighteen minutes of air time.
As always, right at the beginning of the show, here is the HF propagation update... Solar activity moving up, the daily sunspot count almost 180 Saturday, and the effective sunspot number, that all-important figure that you feed to your HF propagation forecasting software was at a nice 137, yes, you heard it right the Effective Sunspot Number SSN was 137 Saturday morning, something that may provide some really interesting DX contacts on the higher frequency bands for amateur radio operators worldwide...
Item two: Radio is a unique hobby, there is never a chance for boredom to build up here... as there are more than 50, yes five zero, more than 50 ways you and I can have a good time playing with our radios... Here is another example... Solar radio astronomy... true, backyard solar radio astronomy is one of the more than 50 ways that you can enjoy radio and learn a lot about our nearest star, the SUN....I'll tell you more about two cheap and easy to implement experiments in solar radio astronomy later in today's weekend edition of Dxers Unlimited, the one and only radio hobby program that provides you with the most up-to-date HF plus 6 meters propagation forecasts, never more than 18 hours old, even if you pick up the late late rebroadcast at just after 0530 UTC on 9820 and 9550 KiloHertz Am plus 9830 kHz Upper side band....
Item three: Dxers Unlimited's Antenna Topics section today will be dealing with the use of low cost downleads for HF antennas, our item four will be the ever popular You have questions, and Arnie tries to answer them, and, time permitting I have a few more items ready to be pasted to the script of the show, which, by the way, you can read by visiting our Dxers Unlimited website or by susbcribing to Dxers Unlimited's mailing list...
Stay tuned, right on this same frequency for more radio hobby information amigos!!! Margarita Delgado is my sound engineer and producer, I am Arnie Coro in Havana, back with you in just a few seconds, after this brief musical interval...
This is the weekend edition of Dxers Unlimited, coming to you from Havana, our e-mail address is very easy to remember, send mail to arnie@radiohc.org.
And here is today's special feature... Solar radio astronomy... Yes, you can pick up radio signals from the SUN, right at your home QTH or at a portable location with even a very simple receiving setup... The SUN is a really powerful source of radio signals that can be tuned using very simple equipment... Here is an example... Find yourself one of those old now retired C band TV receive only satellite systems.. the ones with the big antennas that everyone around the world seems to be phasing out or service... Many of those systems can be obtained just for the asking, as no one seems to be finding a way of using them now that higher microwave frequencies direct broadcast satellites are in service...
Well amigos, even the smallest of the Band C parabolic reflectors connected to even the most primitive TVRO receiver is capable of providing a signficant signal from the Sun, by just aiming the dish towards the Earth's nearest star! As a matter of fact, you will be able to aim the parabolic reflector by just looking at the TV set's screen noise level... The higher the noise level, the better your dish is aimed at the Sun... Once you have tested the old TVRO band C system in this very easy to do way, then phase two of the project will take more time, as you will need to decide whether you want to do spot observations and measurements of the Sun's microwave energy output on the C band, from 3700 to 4200 megaHertz, or you want to run a more advanced setup that will actually track the Sun from sunrise to sunset and record the solar activity on that 500 megaHertz segment of the microwave spectrum...
Again, even the older systems that did not had very low noise pre-amplifiers will provide a significant increase in noise level when the parabolic antenna is aiming exactly at the Sun, and if your system happens to have an analog S type signal strength meter, you can demonstrate how it works to your family and friends by letting them see how the Signal Strength indicator moves up as the antenna focuses on the Sun! Of course that making the system track the Sun involves a rather complicated mechanical setup, but all I can tell you is that I know about several people that have already build their own tracking systems and are now able to record at least 6 hours of solar activity using a VCR...
Solar radio astronomy is particularly interesting during solar maximum years, like the ones we are going through now... according to scientists the maximum of solar cycle 23 occurred during the year 2000, but we will still be seeing a lot of very interesting solar maximum related events for the 6 to 12 months, so you are still in time to install your own solar radio astronomy home observatory and even register some of the many solar flares expected by scientists, as flares are more frequent immediately after the solar maximum...
There are other ways of assembling simple solar radio telescopes, but the obsolete C band TV Receive Only systems are the easiest ones to get running and will certainly make excellent high school or radio clubs science fair projects for the younger generation...
This is the weekend edition of Dxers Unlimited, and here is item three... our very popular Antenna Topics section... today I'll tell you about low cost alternatives to expensive coaxial cable downleads... Here at CO2KK my amateur radio station I only used coaxial cables for the VHF and UHF antennas, as I run all my HF antennas using either homebrew open wire line or a very low-cost twin-wire line that is used by the phone company to bring in the telephone service from the telephone pole terminal box to the home of the subscriber... It happens that this particular type of twin-wire line is usually made with number 19 pure copper wire, and each of the two wires is insulated nowadays using high quality low density polyethylene, a plastic that is a wonderful low loss insulator even at VHF and UHF frequencies...
The typical phone company downlead is weather resistant, and very well built, as a matter of fact the outer jacket that sorrounds both conductors makes mechanically a very tough cable indeed... Some time ago, I was able to take some samples of the phone company downlead to a local electronics laboratory and measure the impedance of the twin line at different frequencies... All the samples showed a very consistent impedance value around 110 ohms! Something that made me a very happy person, as by simply connecting two of those lines in parallel, PRESTO... MAGIC.... you are the happy owner of an ultra low cost, low loss 55 ohm parallel downlead....
Now many of you will ask me for sure... Arnie Coro, my friend, but most every piece of radio equipment nowadays uses coaxial input systems, and this MAGIC LINE you are talking about made by parallelling two phone company downleads is a 55 ohm balanced line!!! Yes, true, absolutely, you are right...but you forgot that making a one-to-one air core balun transformer is something very easy to do.... So, here is what I do.... I assembled a trifilar one, yes you need three wires for this balun, a trifilar wound, one to one balanced to unbalanced transformer... then I connect the balanced four wire 55 ohm line to the balanced side of the balun, and just run a short length of 50 ohm coaxial cable to the antenna tuner's input.... And that's it... I can assure you that is the easiest to build and less expensive transmission line of them all. The local phone company will provide short lengths for free... so you can obtain enough wire for installing several antennas just for the asking... AND, the four wire parallel like is very easy to splice too... no need for expensive coaxial plugs and barrel connectors...The two parallel lines are held together with UV resistant plastic tie wraps placed at about 20 centimeters or ten inches apart.
NOW, listen to this... the 55 ohm parallel line showed a loss of just about 1 decibel at 29.7 megaHertz for a length of about 30 meters or 98.4 feet, well, almost 100 feet... and that, amigos, is better than most of the typical coaxial cables that you can find. The four-wire line can handle up to 1 kilowatt power easily and I have been using it for the past two months feeding a multiband dipole antenna that from which I am receiving excellent reports on all bands from 40 to 6 meters, from a wire system that is just 24 meters overall length.
If you want to know more about the 55 ohm ohm parallel twin line made from phone company downlead, just send me an e-mail to arnie@radiohc.org, or a post card via Air Mail to Arnie Coro, Radio Havana Cuba, Havana, Cuba and I'll be happy to answer your questions related to this very low cost downlead that you can make yourself with phone company line and a few plastic tie wraps!!!
And now amigos, 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 activity is moving up, solar flux will maybe reach as high as 200 units during the present rotation... Maximum useable frequencies after sunset are going to rather high figures, so be on the lookout for DX on the 12 and 15 meter amateur bands even late in the evening your local time... Sporadic E openings are likely to continue during the next six week, but their yearly maximum usually happens from now until the end of June, For those of you participating in the UK six meter club and the ARRL VHF QSO party contests
here is a special advisory... there are good chances of transatlantic multiple hop sporadic E openings during the duration of both contests this weekend... I will be operating CO2KK looking for contacts for both contests starting at around 20 hours UTC Saturday, as soon as I return home from taping this show, amigos!
Don't forget to send your comments about the show, signal reports and radio hobby related questions via e-mail just after you finish listening to the program... send e-mail to: arnie@radiohc.org, or write a postcard to Arnie Coro, Radio Havana Cuba, Havana, Cuba, do remember that your e-mail, postcards and letters are essential to keep this show alive and well, at your service and providing exactly what you want to hear!!!
Arnie Coro CO2KK
Havana, Cuba
June 09, 2001Postal address:
Arnie Coro, "Dxers Unlimited"
Radio Havana Cuba, Havana, CUBA
e-mail: arnie@radiohc.org
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