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Re: [HCDX] Dxers Unlimited's mid week edition for 26-27 June



Radio Havana Cuba

Dxers Unlimited

Dxers Unlimited's midweek edition for 26-27 June 2007

By Arnie Coro

radio amateur CO2KK

Hi long time amigos radioaficionados and those who are listening for the 
first time too... welcome to the midweek edition of Dxers Unlimited that 
is certainly a very special one, as at the time you are listening to the 
program, our nearest star the Sun has been inactive for a very long 
period, with the daily sunspot count at ZERO for many consecutive 
days... Now a new sunspot active region is slowly rotating into view, 
and that will probably increase the solar flux above the extremely low 
67 and 68 flux units that it has been hovering as of late. By the way, 
any solar flux figure below 70 units , automatically sends the sunspot 
count to ZERO .

Item two: Thank you amigos, to the many friends around the world that 
have already sent birthday greetings..ahead of time, as I will be 
celebrating my birthday Monday of next week. Some came in as early as 
yesterday evening, as it seems that some of my good friends have very 
well structured computerized data bases with their amigos birthdays 
records !!!

Item three: Listening Friday evening on the AM medium wave broadcast 
band to the recently upgraded Radio Reloj Pinar del Rio provincial 
relay, operating on 790 kiloHertz and running 20 kiloWatts, its another 
of the new solid state high technology transmitters that are replacing 
the old power hungry vacuum tube broadcast equipment, in an effort by 
Cuban broadcasting to make more efficient use of electricity by 
replacing the obsolete transmitting plant as financial resources become 
available. The new 20 kiloWatt 790 kiloHertz transmitter is located on 
the outskirts of the city

of Pinar del Rio , about 100 miles west of Havana, and tests done by 
RadioCuba engineers show that it has an overall conversion efficiency of 
around 80 percent... that meaning that the new Radio Reloj relay will 
save a lot of electricity while providing a much better service, because 
it is also capable of modulating the carrier wave on positive peaks up 
to 125 percent... A similar 10 kiloWatt transmitter was recently 
installed by RadioCuba for the Radio Reloj City of Havana station on 950 
kiloHertz, something that has improved the coverage of Radio Reloj in 
three of the nation's western provinces.

More radio hobby related information coming to you in just a few seconds 
as Dxers Unlimited's weekend edition continues...

...............

Si amigos, wish you could join my modest birthday party next Monday 
afternoon... I will be meeting with family and friends for the 
celebration, with little Claudia, my youngest daughter now almost two 
and a half years old, Teresita, my elder daughter , Arnie Jr. and Roxana 
my wife having prepared a cake and ice cream

party !!! Now here is the next item of today's program: Just added a 
Light Emitting Diodes home brew lamp to act as the back light of my 
favorite 2 meters band FM transceiver that was constantly burning the 
very difficult to replace incandescent pilot lamp that illuminates the 
liquid crystal display. A white light emitting diode and a resistor did 
the job that , according to LED manufacturers specifications won't need 
to be replaced in a very long , long time. I also did a similar 
incandescent light bulb replacement on my small portable, a Grundig 
FR200 " Recycle Power"radio. On this radio I replaced the high intensity 
miniature incandescent lamp dash emergency light with a cluster of three 
high intensity white diodes, that give a lot of light and use less than 
half the electricity that the incandescent bulb requires to operate. 
Some time ago a long time Dxers Unlimited listeners sent me the photos 
of his modified Grundig FR200 receiver , to which he had changed the 
light bulb for three high intensity white Light Emitting Diodes with 
great success, and I just followed upon this nice idea .

The other modification that he made consists on an electronic 
band spread, that is a voltage variable silicon diode that was added to 
the local oscillator tuned circuit on the short wave bands, making 
tuning a lot easier than with the radio's original mechanical analog 
tuning. He told me that he could set the analog dial to a specific 
position on the blank calibration scale, and then tune the radio with 
the varicap

diode. Another thing he did to this very special "emergency

radio" was to add a beat frequency oscillator, so that single side band 
and CW stations could be picked up..The BFO is switched on and off by a 
miniature switch located on the back of the radio, right next to a 
second variable resistor to control the voltage to a second voltage 
variable or varicap diode.

One of the really nice features of the Grundig FR200 is that it uses up 
very little electricity to operate... as a matter of fact three standard 
double A cells will last for quite some time if you use the radio for 
casual listening.

Again, it's an excellent set to have around in case there is a power 
failure, and even if your batteries go dead, the Grundig FR 200 has a 
crank type Direct Current Generator that will charge a small nickel 
metal hydride battery pack, and even if the pack is in bad shape, the 
radio will keep working all the time that you are cranking the generator !!!

.......

Si amigos, despite doomsday predictions that the radio hobby will just 
vanish due to the now everywhere Internet, it's just not happening, and 
what a paradox, the Internet is actually helping the radio hobby in the 
specific case of amateur radio.

Never before in the more than one hundred years of the existence of our 
wonderful hobby we have seen so much valuable information been made 
available freely... There are thousands and thousands of amateur radio 
websites, and the amount of technical information that can be downloaded 
is absolutely amazing... There are websites that require many , many , 
hours to just take a look at, like the super antenna site courtesy of 
W4RNL , Dr. L.B. Cebik, that can be found at http://www.cebik.com.... 
There are sites devoted to specific

modes like the Dr. Oliver Phelp's digital communications mode website, 
and there are also lots of sites devoted to radio wave propagation, 
home brewing of radios, contests, antique radios... you name it, so 
again, we are seeing a very interesting thing happening in front of our 
eyes... the Internet, that was supposed to be the end of amateur radio 
and the radio hobby in general, is actually now helping more and more 
people enjoy the hobby in a much more plentiful and I must add also 
inexpensive way !!! But be aware that some radio amateurs think 
different as regards to making their websites freely available to anyone 
, by demanding copyright privileges as if their websites were run as 
commercial operation... but fortunately those are just a few exceptions 
and the true amateur radio spirit of cooperation with anyone interested 
in the promotion and development of the radio hobby seems to prevail in 
at least a one hundred to one ratio in favor of freely available 
technical information.

.....

Si amigos, yes my friends, thanks for joining me today on this mid weekk 
edition of Dxers Unlimited... And now here is the very popular antenna 
topics section of the show...

devoted today to a peculiar antenna system that is known

as  " The DIPOLES NEST ", a very easy to home brew  High end of the HF, 
low band VHF and high Band VHF antenna.

A few weeks ago I quickly assembled a NEST OF DIPOLES, to solve a 
friend's antenna problem... The system has

a dipole cut for 28.4 megaHertz on the 10 meters band, his favorite HF 
band, another one cut for 50.3 megaHertz on 6 meters and yet another one 
cut from 145.000 megaHertz on 2 meters.

They are all fed using the single RG 58U 50 ohms coaxial cable that 
my friend had at hand, and as expected, I used a  first balun choke coil 
for the two meters dipole, made by looping 6 turns of the cable on a 1.5 
inch diameter PVC pipe coil form, followed by another air wound choke 
coil of 6 inches diameter aiming at decoupling the radio frequency of 
the 10 and 6 meters band from from flowing on the outside of the braid 
of the coaxial cable.

The dipoles were made with number 8 PVC insulated copper wire, something 
that required careful tuning of each dipole, because the dimensions of 
antennas using insulated wires are different from the ones using bare 
copper or aluminum wire.

Anyway, the three dipoles are kept separated from each other by  small 
lengths of polyethylene pipe, and in a second antenna, the separation 
between the dipoles was achieved with lengths of the center insulator of 
heavy duty RG17 coaxial cable, also an excellent HF, VHF and UHF 
insulating material.

The procedure to set up the antenna involved using a good quality HF 
standing wave ratio meter for tuning up the 10 meters band antenna first 
, and a similar VHF instrument for setting up the 6 and 2 meters bands 
dipoles in sequence. In this second version, as always, something new 
came to my mind, and we decided to include yet another dipole, a fourth 
one, tuned to the center of the aircraft VHF band...that for voice 
communications spans from 118 to 136 megaHertz, so we cut the dipole for 
127 megaHertz. This antenna was not adjusted for transmission, because 
it will always be a receive only antenna as you may realize.

The four dipoles " Nest of Dipoles" HF, plus 3 VHF bands antenna works 
very well on 10 meters, 6 meters, the aircraft band and the ham two 
meters band.

Installing the two antennas was a rather easy job, as they are quite 
compact... because the longest dipole, the one for 10 meters is just 
about 5 meters or 16 feet long. Both antennas were installed as 45 
degrees tilted dipoles, a compromise to achieve good pick up and 
transmission of both vertical and horizontally polarized waves.

If you need to install these dipole nests at a distance longer than 
about 20 meters or 60 feet from your radio equipment, then please 
consider the need to change to more expensive and less loss coaxial 
cable types, like the RG-213 or RG-8, in order to reduce the signal loss 
typical of the RG58 type cables.

By the way , a similar dipoles 'nest' can be built for other frequency 
ranges too... VHF-UHF radio amateurs can make

a nice nest for 6 meters, 2 meters and 70 centimeters, and ideal system 
to carry on the backpack with one of the new ultracompact multi band 
amateur radio transceivers like

the YAESU FT817 or the ICOM 706...These antennas are

lightweight, easy to repair on the field, and will cost you next to 
nothing as compared with similar commercially built

versions...But again, I insist that you will need to invest quite

some time adjusting them for minimum standing wave ratio...

And now amigos, as always at the end of the show here is our exclusive 
and not copyrighted HF plus low band VHF propagation update and 
forecast... The latest forecast for the solar minimum is telling us that 
it may be actually happening right now , but other scientists believe 
that the tail end of solar cycle 23 will extend until the first half of 
2008. The latest solar data are simply typical of minimum solar activity 
with zero sunspot count, solar flux below 70 units and a very quiet 
geomagnetic field...the expected average sunspot number for June is 
expected to reach the rock bottom figure of 5... Expect also some really 
amazing sporadic E skip openings during the next several days ,with 
multiple hop E skip giving radio amateurs the unique opportunity of 
working transcontinental DX between Africa, Europe and the Americas. 
Don't forget to set aside a little of your valuable time to send me a 
signal report and your comments about the program, send them to 
arnie@xxxxxx, again arnie@xxxxxx and VIA AIR MAIL, send mail to Arnie 
Coro Radio Havana Cuba, Havana, Cuba  . Hope to have you all listening 
to our weekend edition next Saturday and Sunday UTC days amigos !!!

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