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SHORTWAVE ON A LIMITED BUDGET
My ancient S-38E Hallicrafters shortwave receiver died a some months ago. I
did not realize until then how much I depended on foreign short wave
broadcasts to keep in touch with world events and to get the news before (!)
it was hot. I could not see spending $75 and up for a new commercial
receiver so that left as the only alternative build-it-yourself conveter
kits.
The October 1989 POPULAR ELECTRONICS feature article told how to build a
sensitive shortwave converter with an old car radio and 6' or shorter antenna
for about $10 worth of parts. This had to be too good to be true. I passed
up buying the issue at the time and regretted it later, after the issue was
gone from the stands. Fortunately, the article was reprinted in the 1990
POPULAR ELECTRONICS Annual (still on the newsstands as I write this). This
time I bit. The converter seemed simple enough to build as there were only a
bare handful of parts involved and nothing tricky such as winding your own
coils. Even etching the printed circuit board was not mandatory since you
could haywire the thing on a piece of perfboard, or so the article claimed.
Just to be safe, I ordered the complete kit of parts, including etched PC
board, but less crystals, from the supplier listed for the sum of $10.50
postpaid.
Prior to the arrival of the kit, I had looked for a used car radio at a Ham
Radio flea market. They seemed to be selling in the range of $1 to $10 per.
I bought a fancy one for $5, and as an afterthough, a "junker" for $1. (Used
car radios are available at flea markets, yard sales, and swap meets.)
The kit arrived in the mail a couple of weeks later. Building the kit itself
took all of 20 minutes, no big deal. Figuring out the hookup to the car
radio was something else again (see enclosed text file CARRADIO.TXT for
instructions). Of course I also had to build a 12-volt regulated and nicely
filtered power supply to provide the juice for the radio and converter (see
enclosed text file POWERSUP.TXT for schematic and parts list this).
All right. Everything was built and connected. I cheated and used a 10'
length of speaker wire strung along the ceiling (I was building it in my
basement so I wanted to improve my DX luck). Turning it on and holding my
breath... I was greeted with a loud burst of static that turned into that old
familiar CW beeping as I twirled the dial, and yes, gabbling in foreign
languages, now Spanish, now German and French. The thing worked!
The converted car radio is surprisingly sensitive. The article claims it can
"outperform most under $150.00 shortwave radios". This may well be the case.
In the last month I have logged all of the following stations:
Radio Sweden, Radio Sofia (Bulgaria), Radio Beijing (China), Deutsche Welle
(Germany), WWV time signals (U.S. Bureau of Standards), Radio Netherlands,
Radio Moskow, Radio Havana, KUSW (Salt Lake City, Utah), Radio Canada, VOA,
Radio Japan, Radio Austria, BBC, Radio Dubai (United Arab Emirates), Radio
France, Swiss Radio, RNY International (pirate station). Not bad for a total
expenditure of about $16.
So, how do you, gentle reader, build one of these babies yourself? The easy
and recommended way is to send your check for $10.50 to the following address
for the postpaid kit:
SMALL PARTS CENTER
6818 Meese Drive
Lansing, MI 48911.
The kit includes the hard-to-get NE602N frequency converter IC, the IF
transformer, and all the caps, resistors, and the diode, as well as an
ectched circuit board. You only need to supply a crystal (if you want to
tune more than one SW band, you need extra crystals). If you can't find
crystals at your favorite electronics store (even Radio Shack sells 'em), you
can order them from Jameco, Digikey, or a host of other mail order suppliers.
=============================================================================
An alternate source of NE602's (@ $2 ea.) is Premier Electronics
3850 Plymouth Blvd., Suite 104
Plymouth, MN 55446
Another source of NE602's (@ $5 ea.) is Star Engineering
3 Golf Center, Suite 297
Hoffman Estates, IL 60195.
The IF transformer, a 10.7 Mhz submini, can be pulled from a junked
transistor radio (it is marked GREEN), or it can be ordered from Digikey,
part no. TK1501, @ about $2. The rest of the parts can probably be found in
your junkbox.
I still recommend ordering the kit from SMALL PARTS CENTER. It only costs a
couple of bucks more and comes with nice documentation. But for those of you
who absolutely insist on building the coverter from scratch, the enclosed
text files give schematics and enough information to enable you to do so
without too much trouble.
P.S. You have to use a CAR radio. Any other type of radio will not work
because of all the interference from local broadcast stations that would be
picked up.
=============================================================================
I would be interested in getting in touch with other SWL's (shortwave
listeners) and also finding out what you think of this particular project.
Send comments to:
Mendel Cooper
3138 Foster Ave.
Baltimore, MD 21224
Again, happy DXing!