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Cobra 139XLR GREAT RX, no TX

A

a2philip

Member
Jun 22, 2012
5
0
11
small town near Hudson,MI
I bought a Cobra 139XLR at a garage sale for $20. The guy didn't have an antenna for it, so I couldn't test it, but it LOOKED like it wasn't subjected to the "golden screwdriver" (no holes or extra switches/knobs) and it lit up and made noise (standard eBay criteria for a "working" radio) so I bought it.

Got it home and hooked it up to an indoor antenna (in-between residences right now) The RX works GREAT (TONS of DX- on an indoor antenna!!) but when I keyed up, the mod meter peaked for a second and went back down. No "swing" when I whistled into the mic. Tried a second time and no meter movement. A few minutes later I tried to show the roomie what was happening and same result (meter peaked first time, not second, no "swing") Could the final(s) be going bad??

I hope it doesn't take too much (money/effort) to get this working, I'm studying to get my Technician license, and from what I've seen on the web, it would be fairly easy to convert this to 10 meter sideband. Worse comes to worst, I could (try to) get my money back selling it on eBay!! (Hey! It's a "working" radio!!)
 

what does extra switches have to do with a golden screw driver?

Check the relay, and the small blue cap next to the final bias test lead

also did you check it on AM or SSB?

not much you can do with that radio on 10 meters with a Tech lic.
 
I've borrowed a copy of the Lou Franklin repair book from a local (don't ask the exact title) and traced it to a bad final and/or driver. Waiting for both from eBay...

"Golden Screwdriver" refers to someone who doesn't know what they're doing (even if they SAY they do) in regards to radio repair and modifications...the "extra" switches or knobs is (usually) how people do channel mods, and "extra" hole (or holes) means it's had either a frequency counter or VFO hooked up to it...not necessarily correctly...

Have had friends who've been there and gone through that...
 
Just FYI, did you try a different mic with it? One that you know to be working?

Recently picked up a minty 29XLR that was advertised as not transmitting. It had the same symptoms you described. Turned out the mic was bad.

Give it a shot, you might get lucky.
 
Zman said:
Finals are no longer available for that radio.. You might just want to throw it away.
Click to expand...

Not so.
He can replace the driver with a 2sc2166 and the final with a 2sc1969 or even a 2sc2312 - IIRC.
Or if he wants to - he can look at some schematics and rebuild the final circuit and adopt a MOSFET to it . . .
 
Robb said:
Not so.
He can replace the driver with a 2sc2166 and the final with a 2sc1969 or even a 2sc2312 - IIRC.
Or if he wants to - he can look at some schematics and rebuild the final circuit and adopt a MOSFET to it . . .
Click to expand...

I was being a smart ass. Thats something a tech at a local CB shop (that i no longer go to) would tell the guy. He doesn't like to work on ANY older radios so his simple reply is to tell the radios owner to simply throw the radio away.

A mosfet will work great in this radio!:D
 
Zman said:
I was being a smart ass. Thats something a tech at a local CB shop (that i no longer go to) would tell the guy. He doesn't like to work on ANY older radios so his simple reply is to tell the radios owner to simply throw the radio away.

A mosfet will work great in this radio!:D
Click to expand...

That's funny. Seems like a tech would want to fix things! I remember there being a thread here where the OP gave detailed info on how to do the Mosfet change. At the time, I think you could still get the regular finals, so a lot of folks wondered "why"? As time goes on, it will probably be the only way to keep an old rig alive. My local tech had said that a lot of the 1969's that are floating around ebay and such are cheap clones, and don't work like they are supposed to.

73,
RT307
 
2RT307 said:
That's funny. Seems like a tech would want to fix things! I remember there being a thread here where the OP gave detailed info on how to do the Mosfet change. At the time, I think you could still get the regular finals, so a lot of folks wondered "why"? As time goes on, it will probably be the only way to keep an old rig alive. My local tech had said that a lot of the 1969's that are floating around ebay and such are cheap clones, and don't work like they are supposed to.

73,
RT307
Click to expand...

The one on E-Bay are junk.. I learned that lesson... The guy im talking about is an older tech and owns his own shop. He only likes to work on newer radios and anything older than 15 years he refuses to work on because of obsolete parts.. Case in point; a friend took a Galaxy 22B to him and he refused to even look at it!! He has lost a lot of customers due to his pickyness but its his shop so he can do what he wants. He also charges by the hour ($65.00 p.h. plus parts) which also scares a lot of customers off.. Ironically, he has a Robyn 520D and a Cobra 139 XLR for sale in his shop but he wants $250.00 for each one!!!!!:eek:
 

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