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Re: [HCDX] Dxers Unlimited's mid week edition for 13-14 March 2007



Dxers Unlimited
Dxers Unlimited weekend edition for March 13-14 2007
By Arnie Coro
Radio amateur CO2KK



Hi amigos radioaficionados around the world and in space! Welcome to the 
midweek edition of Dxers Unlimited reaching you when solar activity is 
still at really very low ebb… I am Arnie Coro, radio amateur CO2KK and 
here is item one of today’s program, solar scientists continue to try to 
solve the puzzle about cycle 23’s final months… some researchers believe 
now that we may see a rather extended tail end of cycle 23, while others 
insist it is almost over by now. Another school of thought continues to 
underscore the very high probability that upcoming solar cycle 24 is 
going to be another record breaker, even capable of matching  super 
cycle 19 that sent the average monthly sunspot count up to two hundred 
and seven, the highest ever recorded .
For us radio hobby people, an upcoming  super solar cycle 24, with a 
very high average sunspot count will also mean many solar flares and 
geomagnetic storms too !!!
Now, we must just wait and see what’s going to happen during the next 
several months, when it would be possible to have a fairly good 
knowledge of the early phase of cycle 24…
Item two: The most popular amateur radio band around the world continues 
to be two meters, spanning in some parts of the world from 144 to 146 
megaHertz, while in other areas amateurs are assigned two more 
megahertz, so the band in those parts of the world goes from 144 to 148 
megaHertz. Two meters is very popular because with very simple equipment 
and low cost antenna systems, radio amateurs are able to communicate 
locally and even at longer distances when propagation conditions are 
good. But the two meters band is not only a good place for FM voice mode 
communications. Amateur operators can make good use of existing 
satellites, and also enjoy very sophisticated communications modes, like 
sending signals of high power transmitters to the Moon, using it as a 
passive reflector as part of an Earth – Moon – Earth or EME link.
I have made several two way amateur radio contacts using the Earth –Moon 
- Earth or EME mode while running at CO2KK, my ham radio station not too 
much power output and a pair of small size Yagi antennas.
But, fully equipped EME capable stations use huge antenna arrays, high 
power transmitters of up to the maximum legal power authorized to 
amateur operators and extremely low noise signal preamplifiers… EME is 
one of the more than 80 ways that you can enjoy our wonderful hobby… 
yours and mine: RADIO !!!
Amigos, Dxers Unlimited’s midweek edition will continue in just a few 
seconds… I am Arnie Coro in Havana, stay tuned or connected to our server:

……..

Si amigos, you are listening to Radio Havana Cuba, the name of the show 
is Dxers Unlimited, and as always its my pleasure to share with you this 
on the air and on the web time devoted to this wonderful hobby “RADIO” 
here is our next item, the most popular section of the show “ASK ARNIE 
“answering listeners questions as fast as they come in via e-mail sent 
to arnie@xxxxxxxxx
Today’s number one question: came from  Canada, from Ontario, listener 
Wilbert asks if he can adapt an FM band Yagi antenna that is sold at a 
popular electronics retailer outlet near his home, so that the antenna 
will work on the 2 meters amateur band… And amigo Wilbert, the answer is 
YES… it can be done, and as a matter of fact, you will end up with a 
very nice looking 2 meters band antenna, at a much lower cost than if 
you try to homebrew one. The typical FM band 5 or 6 elements YAGI 
antenna has a boom length that provides more than enough space for a 6 
to 7 element 2 meter band Yagi, and the length of the elements allow you 
to cut them to the segment of two meters where you want to operate.
After buying the commercial FM broadcast band YAGI, you must
proceed to carefully measure each element and write down the result of 
the measurement.
You will find that as in any typical Yagi parasitic array, the elements 
lengths go from the longest one, the reflector, that will be very near a 
half wavelength at the operating frequency, to the shortest one , the 
last director, that will be much shorter than a half wavelength.
The FM band Yagi will probably be cut for a frequency around 100 
megaHertz, because that is roughly the center of the FM broadcast band 
that spans from 88 to 108 megaHertz, and that means that the longest 
element of your commercially built Yagi will be very near 1. 5 meters 
long, that is almost 5 feet long.
The second step required for converting a commercial FM band Yagi for 
the amateur 2 meters band is to decide to which segment of two meters 
you want new antenna to be optimized. For example you may enjoy talking 
to friends on repeaters located in the upper two megahertz of the 2 
meters band, from 146 to 148 megaHertz, so you may want then to optimize 
your YAGI for a center frequency of 147 megaHertz, which is not exactly 
the optimum way of doing it, but that in actual practice works quite well.
The third step is to use any of the available freeware programs that 
calculate YAGI VHF antennas, and run it with the 147 megaHertz center 
frequency design target.
Those programs generate several outputs: they will give you the length 
of each element; how the elements are spaced along the antenna’s support 
boom and also you will be able to see the actual theoretical horizontal 
and vertical radiation patterns.
Your fourth step requires the use of a measuring tape and a hacksaw, to 
cut the elements to the required lengths, following the data provided by 
the YAGI antenna calculating software.
Fifth step, requires using an electric drill to carefully locate and 
drill the holes where the elements will be fixed to the boom, that will 
not be the same ones used for fitting the elements to the original FM 
Yagi antenna
The sixth and almost last step requires a decision on your part, it you 
want to operate using horizontal or vertical polarization. Using 
horizontal polarization as needed for operating on CW and single side 
band modes at the lower edge of two meters needs no change to be done to 
the boom, but if you want to use vertical polarization, as required for 
FM voice and packet radio modes, then you must drill new holes so that 
the antenna may be installed for vertical polarization, in other words 
the support clamp will be at 90 degrees from the original position used 
for receiving FM broadcast band horizontally polarized signals..
The last step is to adjust the antenna for minimum standing wave ratio, 
and for doing this you will need a VHF standing wave ratio meter, and 
the help of an experienced radio amateur that has adjusted Yagi antennas 
before… Take good notes of what you do, write them down, so that in the 
future you will be able to adjust other antennas all by yourself…
Amigo Wilbert, I am sure that you will be able to find at a local radio 
club someone willing to help you with your antenna conversion project… 
And don’t forget that a YAGI with 5, 6 or 7 elements is a highly 
directional antenna that requires the use of an antenna rotor if you 
want to have around the compass coverage!!!

…….

QSL , QSL , QSL on the air from Havana to the many Dxers Unlimited 
listeners around the world that have written during the past several 
weeks reporting good reception of our 6180 kiloHertz English language 
program heard between 05 and 07 UTC. The antenna we are using on 6180 
kiloHertz is our Central North America curtain array, it is technically 
speaking according to ITU definitions an HR 4, 4 , 0.8 system, that 
meaning that it has 4 sets of dipoles set in four rows and four columns 
a configuration that provides close to 20 decibels of effective antenna 
gain over a half wave dipole placed at the center of the array. If you 
are picking up Radio Havana Cuba on 6180 kiloHertz in English from 00 to 
05 UTC,you are listening to the same antenna and transmitter combination 
too.
Item six: For more than fifty years I have been fascinated with my 
father’s 14teenth birthday present… a regenerative radio receiver kit 
that he was sure I was going to be able to assemble without any help, as 
dad told my uncle Armando during the birthday party.. that little radio, 
assembled breadboard fashion is still working after half a century have 
passed, and it has also served as the prototype for many other clones 
that I have helped to build all along these years. The latest version of 
my BIRTHDAY Regenerative is a bit more sophisticated than the original 
one, and works beautifully with the sets of plug in coils that its proud 
owner my eleven year old grandson has built so far… As batteries are 
hard to come by locally and very expensive, this version of Arnie’s 
Birthday Regenerative uses a very safe 24 volts DC supply to power my 
grandson Arnie Coro the Fourth wonderful new toy!!!!
If you want to learn more about my BIRTHDAY Regenerative receiver, just 
drop me an e-mail to arnie@xxxxxx or a postcard to Arnie Coro, Radio 
Havana Cuba, Havana , Cuba asking me to send you the Birthday 
Regenerative receiver information package…
And now, as always at the end of the show, here is Arnie Coro’s Dxers 
Unlimited, HF plus low band VHF propagation update and forecast…Let’s 
begin with the actual sunspot count on Monday  was   11 . The effective 
sunspot number Tuesday morning local time in Havana, around 14 hours UTC 
was 10    , with the maximum useable frequency curve going as high as 35 
      megaHertz over parts of Africa, a good indication of the excellent 
equinoctial propagation we are enjoying despite the very low solar 
activity. The BAD news is that we are now seeing the effects of yet 
another geomagnetic disturbance as the solar wind is bringing in a much 
higher than usual proton count… Keep time available for DXing from about 
an hour before your local sunset to three or four hours after sunset, 
and enjoy a second propagation peak starting at around two hours before 
sunrise, and extending no more than an hour after sunrise…
  And don’t forget to send me your comments about this program, signal 
reports QSL requests and radio hobby related questions to arnie@xxxxxx, 
or VIA AIR MAIL to Arnie Coro, Radio Havana Cuba, and Havana, Cuba


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