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Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
Ok, as some of you may know I've been working slowly on a high altitude, long range glider project for nearly a year now. I've got bits and pieces of the instrument package all figured out, but the FM receiver for the control uplink has thus far eluded me.
I finally came across some promising documentation on a chip family made by Motorola for just such an application. Its the MC13135(older)/MC13136 dual conversion narrow band FM receiver chip.
Trouble is, this thing is bloody IMPOSSIBLE to find. Datasheets are widely available with a google search, but I've tried everywhere, and nobody stocks it. Possibilities excluded are: Newark, Mouser, Allied, Digikey, JDR, Freescale (motorola's own distributor), On Semi, and eBay.
They are popular in car audio and some desk top/home stereo systems apparently. I've got a radio I can tear apart when I get home, but I think its a bit old to be a possibility. Anyone ever seen this part? Got a couple laying around? Maybe have a junk stereo in your junk box you can check?
If anyone knows of suppliers that specialize in RF or difficult to find components, I'd definitely be interested.
Registered Member #16
Joined: Thu Feb 02 2006, 02:22PM
Location: New Wilmington, PA
Posts: 554
I looked at alot of designs and datasheets, but I've decided because of the safety ramifications if the receiver on this project were to fail (read: 6lb, $800 object falling 30,000ft and hitting whatever is below it) I probably need to bite the bullet and go commercial.
The best candidate at this point is the Alinco DJ-X7T wide band receiver. At $170, its spendy, but it will be extremely rugged, and allow a great deal of versatility (switching freqs or uplink bands entirely if noise is a problem, etc). Its also got better sensitivity than anything I could build, and has the added bonus of CTCSS decode, for interference prevention.
It claims to weigh 100g in its out-of-the-box state. Thats plenty light enough, but I'm betting I can get it down alot closer to 50-70g by the time I'm done with it.
I'm currently drawing up the first really detailed outline of the instrument package requirements and capabilities for this project. Once I've got a firm outline worked out. I'll post a thread.
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Elusive FM Receiver Parts
