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Re: [HCDX] Dxers Unlimited's mid week edition for 28-29 August 2007
Radio Havana Cuba
Dxers Unlimited
Dxers Unlimited’s mid week edition for 28-29 August 2007
By Arnie Coro
Radio amateur CO2KK
Hi amigos radioaficionados around the world and orbiting the Earth …
welcome to the mid week edition of Dxers Unlimited. I am Arnaldo, Arnie,
Coro, your host here at this twice weekly radio hobby program that will
be on the air for the next sixteen minutes… Here is item one: Still no
signs of the expected jump in solar activity that will signal the start
up of cycle 24…. Scientists keep watching the Sun in search for reverse
polarity sunspots …. Item two: Imagine a low cost amateur radio repeater
well above the Earth’s stratosphere…It is perfectly possible to assemble
one such high altitude repeater from readily available components and
put it as the payload of a high altitude balloon… Here is a very recent
example of that unique way of providing over the horizon VHF and UHF
communications, at least for the lifetime of the balloon.. The news
comes from Finland and it explains that after what was considered to be
a successful maiden flight two weeks ago, there will be another
IIlmari balloon flight next weekend. The flight is scheduled for 06 UTC
on Sunday, September 2nd, 2007, from Sappee, Finland, grid square
locator (KP21GJ).
The high altitude Ilmari balloon should be workable from many parts of
north-eastern Europe, if it goes as high up as the previous flight (30
km), yes you heard it right, the Finnish radio amateurs were able to
make their experimental high altitude repeater go up 30 kilometers ,
thus giving it a really wide coverage area. They do recommend potential
users of the Illmari high altitude balloon repeater to keep the
effective radiated power at low levels, saying that even 1 watt is
plenty for working Ilmari's 2m/70cm ssb/cw
transponder! The balloon will have APRS(-IS) callsigns that probably
will be assigned as OH2SIX-11 and/or -12.
A URL site with the information about the Illmari high altitude balloon
repeater experiment is available at http://wiki.ham.fi/Ilmari-2007b
providing detailed operating
instructions and another site with the URL
http://www.kolumbus.fi/michael.fletcher/ilmari.htm has or
pictures and information from the maiden flight.
Many amateur radio clubs around the world have done similar experiments
with high altitude balloons carrying not only amateur radio repeaters,
but also equipped with TV cameras transmitting back to Earth via 70
centimeters band Amateur Television .
A possible future high altitude repeater may form part of tests of a
unique solar powered aircraft, capable of staying up for long periods
while flying at altitudes of around 20 to 22 kilometers above the Earth.
These “robot” solar powered planes use highly efficient electric motors
and large size propellers capable of providing enough lift even at such
high altitudes where the air has a very low density. The electric robot
planes can lift smaller payloads, but present day technology makes
possible designing and building very compact and lightweight repeaters
with 2 meters band input and 70 centimeter band output frequencies…
Stay with us as Dxers Unlimited’s mid week edition will continue in just
a few seconds, after a station ID… I am Arnie Coro in Havana.
…….
You are listening to Radio Havana Cuba, the name of the show is Dxers
Unlimited, and YES, we do verify reception reports, and also answer your
radio hobby questions sent to arnie@xxxxxx or VIA AIR MAIL to Arnie Coro
, Radio Havana Cuba Havana, Cuba
Here is now our next item of today’s show, our technical topics section
of Dxers Unlimited, that will be telling you about my most recent
version of the universal linear power supply for solid state equipment…
Last week I was finally able to find time to spend at the workshop and
give the finishing touches to a project that had been waiting for a long
time. The universal linear power supply for solid state equipment, that
uses readily available components, is easy to homebrew, and has built in
protection against short circuits and over voltages. This power supply
has a variable output range that goes from 0 volts to 30 volts DC, and
several fixed voltage outputs set at 4.5, 6. 9. 12, 13.8 18
And 24 volts DC, all at a current maximum of 2 amperes, more than enough
for low power electronics experiments.
The 2 ampere maximum capacity will eventually be upgraded to 5 amperes,
when another project left halfway to completion is finished… that is
winding a new transformer for the universal linear power supply.
This supply is an excellent addition to the workbench, as it is capable
also of measuring the current used by the circuit under power, giving
you a good idea of how the new designs are evolving. The current meter
is calibrated in three scales that go 0 to 30 miliampers, 0 to 300
miliamperes and 0 to 3 amperes, that will have to be modified when the
new transformer is installed.
The power supply already in use is kept operating full time when I am
working in my electronic workshop, providing power to the 2 meters band
handie talkie that I keep on the local Havana metropolitan area repeater
on 145.190. I normally use the 9 volts DC output to provide power to the
YAESU FT2008 FM 2 meter band handie talkie, that works quite well within
the voltage range of 7.2 to 12 volts DC.
All the other outputs of the power supply are free, and can be used to
power other equipment or for test purposes.
In order to have a very smooth well filtered direct current output , I
used the 5000 microfarads per ampere rule, so the power supply has three
five thousand microfarads at 35 volts DC working volt electrolytic
capacitors, that will soon be replaced with a single 22,000 microfarads
at 50 volts DC working voltage capacitor, so that it can be used when
the new higher current rating transformer is installed.
Having such a wide voltage range, fully measured and short circuit an
over voltage protected power supply is something I recommend to all
electronic hobbysts and radio amateurs that like to homebrew and repair
solid state equipment.
…..
And now la NUMERO UNO… ASK ARNIE, the most popular section of Dxers
Unlimited, closely followed by the HF plus los band VHF propagation
update and forecast and the technical topics section of the program…
Today’s ASK ARNIE question came from Surinam, where listener Dersi wants
to know if it is worthwhile to buy broken down radio receivers from a
local dealer that is selling them at very low prices. Well amigo, if the
price is low, you have almost nothing to loose and a lot to gain… In
many instances broken down solid state receivers can be fixed by someone
willing to spend more time than the time usually spent by a dealer’s
repair technician… Especially lower priced radios are usually just
tossed away instead of spending expensive labor in attempting to fix
them… But beware that you may find the cause of the breakdown sometimes
by just opening up the receiver’s case… For example, just recently a
neighbor gave me an old transistor radio, so old in fact that it uses
germanium transistors… He had taken it to the repair shop and they told
him that the set was beyond repair…
It took just ten minutes, using classical signal injection techniques to
find out that the first audio amplifier transistor was not operating…
Putting in a new transistor, that wasn’t new at all, because I had
recycled it from energy saving fluorescent light lamp…Although the
transistor from the lamp has more gain than the one it replaced, the
only minor chage required was to increase the value of the emitter resistor.
A quick realignment using the workbench signal generator and the digital
multimeter, brought the little transisor radio
back to several more years of useful life !!!
………
Si amigos, short wave listening, tuning in to stations from 3 to 30
megaHertz is one of the most popular aspects of the radio hobby , you
can tune in to the many users of that frequency range, from
international short wave broadcast stations , to aircraft long range
communications , time and frequency standard stations, as well as the
several million active amateur radio stations worldwide. But nowadays
one of the things that really worries me about short wave listening is
that many newcomers to this hobby are making their entry using very poor
radio receivers, in fact so badly designed and built radios that many
people simply drop any further efforts to “listen to the world” as many
sales promotions for those receivers say… My advise is that if your
present radio receiver is a very low cost one, and you are experiencing
difficulties when tuning in stations, think about the possibilities of
buying a better receiver, that will obviously is going to be more
expensive, several times more expensive than the cheap little radio ,
but that will be able to provide much better reception with good
frequency indication in the form of a digital frequency display , and
equipped with an input connector for installing an external antenna
system. You will feel the difference immediately and start tuning the HF
bands much more frequently with much better results,,,
……
Human powered radios....using radios that obtain their electricity from
a person winding a clockwork , hand cranking a generator or pedalling a
stationary bicycle connected to a generator recently made number 78,of
the now more than 81 ways you and I enjoy our hobby.
Yes amigos, Walt , ae Canadian listener from Nova Scotia has convinced
me that human powered radios open up yet another way of enjoying our
hobby in a unique way... Now those who criticize us radio hobbysts as
potato couch guys, will be surprised to learn that we can share two
wonderful hobbies at the same time... exercising with a stationary bike
and generating our own electricity to power the radios.
After receiving Walt's e-mail, I attempted to couple a small generator
to a bicycle that I had kept in the garage for several years, and all I
can say is that IT WORKS !!! The small direct current generator that was
originally intended to power the headlight and a small taillight for the
bicycle, provided enough power to make a small transistor radio
work quite well, after I added a big ten thousand microfarad capacitor
in parallel with the generator output. Please note that this generator
was not charging a battery, but feeding directly the radio with its
direct current output that was very near 6 volts when I pedalling at
slightly below my long range biking cruising speed...
......
And now as always at the end of the program, here is our exclusive and
not copyrighted Arnie Coro’s Dxers Unlimited HF plus low band VHF
propagation upate and forecast…Solar activity will continue at very low
levels, solar flux around the 70 units baseline, and the daytime maximum
useable frequencies are still well below the figures I expect them to go
in about 2 more weeks when we enter into the autumn equinox period of
much better short wave propagation. Remember to send your signal reports
and comments to arnie@xxxxxx, and VIA AIR MAIL to Arnie Coro, Radio
Havana Cuba, Havana, Cuba, Hope to have you listening to the weekend
edition of Dxers Unlimited Saturday and Sunday amigos…
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