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