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Picked UP A Cobra 139XLR
- Thread starter DJboutit
- Start date
B
BOOTY MONSTER
Guest
back in the day that was the base to have for us common folks in the lil town i was in . alas.....i only had a 89xlr but she was 10-8 !! 
Good radio, indeed. I'd make sure oyu have it checked over very carefully to make sure the local shop properly aligned the PLL section, otherwise your SSB operation will be crap.
DTB,
you seem to be hinting at some prior experience with a certain common problem here.
maybe i am wrong.
i am a big fan of this chassis, and am quite curious to know if there is a trick or two to aligning the PLL section of this radio.
i have aligned mine and have no problems with it, but i always enjoy hearing about an inside tip.
thanks,
loosecannon
you seem to be hinting at some prior experience with a certain common problem here.
maybe i am wrong.
i am a big fan of this chassis, and am quite curious to know if there is a trick or two to aligning the PLL section of this radio.
i have aligned mine and have no problems with it, but i always enjoy hearing about an inside tip.
thanks,
loosecannon
No, thats just good common practice for any SSB rig. If its not aligned correctly, it won't work well on SSB, as in off freq, etc.
i gotcha,
like, the 7.8mhz IF cans are mistuned; causing "unclarifyability".
LOL that's 8 syllables!
well, i'm a big fan of this chassis.
i've tried to get some techs' opinions on the D21&22-4.7K resistor audio mod thingy, but never could get an answer as to whether or not it messes up the speech compressor circuit or improves it.
i have it done to mine, and i get good reports, but i have never heard it with my own ears. (dont play with that one much)
loosecannon
like, the 7.8mhz IF cans are mistuned; causing "unclarifyability".
LOL that's 8 syllables!
well, i'm a big fan of this chassis.
i've tried to get some techs' opinions on the D21&22-4.7K resistor audio mod thingy, but never could get an answer as to whether or not it messes up the speech compressor circuit or improves it.
i have it done to mine, and i get good reports, but i have never heard it with my own ears. (dont play with that one much)
loosecannon
That's one mod I've never tried. The compressor on those is so effective that I'd personally never modify it, beyond possibly a bit of toying with the range of the AMC adjustment.
i just got one too. where do you buy finals for the thing. mine are toasted and roasted like No key whatsoever
i Bet yours doesnt have blue meter lights tho. HAHAHA Looks pretty shweet huh. matches my Galaxy. Cobra on bottom in case you cant tell lol.
first check the relay.
make sure it is engaging and disengaging properly.
if not, good luck. you'll need it to find another one.
if relay checks out ok; try replacing C179 (near final and driver) with a 2.2uF 25v electrolytic capacitor. (stock part is a tantalum cap, and is notorious for going out.)
if thats not the problem, the driver is a 2SC1306, which isnt made anymore, but you can replace it with a 2SC2166.
the final is a 2SC1307, but again, not made anymore. can be replaced with a 2SC1969, or an NTE236. (1969 preferred)
you must re-bias the final and driver when replacing either.
driver should be at 40mA
final should be at 70mA.
also be wary of the MV1Y diodes that are heatsinked to the driver and final. if you cant bias the driver and /or final.
its a good guess that these have gone. best to replace with original part from junk radio.
also, while you are messing around inside that radio; all of the 2SC1419's should be replaced with NTE152's.
the one near the PLL should be moved to a big hunk of metal inside the chassis, and have wires going to the PC foil traces.
check for burnt foil traces near this transistor and the big resistor covered in teflon behind it.
best of luck, great radio!
loosecannon
make sure it is engaging and disengaging properly.
if not, good luck. you'll need it to find another one.
if relay checks out ok; try replacing C179 (near final and driver) with a 2.2uF 25v electrolytic capacitor. (stock part is a tantalum cap, and is notorious for going out.)
if thats not the problem, the driver is a 2SC1306, which isnt made anymore, but you can replace it with a 2SC2166.
the final is a 2SC1307, but again, not made anymore. can be replaced with a 2SC1969, or an NTE236. (1969 preferred)
you must re-bias the final and driver when replacing either.
driver should be at 40mA
final should be at 70mA.
also be wary of the MV1Y diodes that are heatsinked to the driver and final. if you cant bias the driver and /or final.
its a good guess that these have gone. best to replace with original part from junk radio.
also, while you are messing around inside that radio; all of the 2SC1419's should be replaced with NTE152's.
the one near the PLL should be moved to a big hunk of metal inside the chassis, and have wires going to the PC foil traces.
check for burnt foil traces near this transistor and the big resistor covered in teflon behind it.
best of luck, great radio!
loosecannon
Really dumb question but
Is the relay that thingy that clicks and unclicks if you will when you key and unkey?? does it move if so ill check to make sure its moving.
Is the relay that thingy that clicks and unclicks if you will when you key and unkey?? does it move if so ill check to make sure its moving.
click and unclicks means keys and unkeys and yes the relays open and close so yes there is movement.
and yes the relays open and close so yes there is movement.