| Author |
Message |
    
Kd4amg
Intermediate Member
Username: Kd4amg
Post Number: 175
Registered: 6-2003
| | Posted on Friday, May 27, 2005 - 10:23 pm: | 
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I have acquired a cobra 142 and the recieve ( ears ) is weak...it HAS been modified to have upper& lower am/ssb channels. The problem is that weak stations are not heard ( hook up another rig and it will hear weak stations, but the 142 never hears them ....not a s-meter problem )
Can you provide a " reciever alignment " to peak out the recieve ? I also need to know which " pots " or " tuning cans are which, and in what order it should be done "..... I want to peak the ears ( rx ) on channel 20 of ordinary cb band.
Thank you in advance
kd4amg (Robert ) |
Bruce
Senior Member
Username: Bruce
Post Number: 2730
Registered: 9-2003
| | Posted on Friday, May 27, 2005 - 10:48 pm: |
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sounds like the receiver rf stage transistor is gone |
Kd4amg
Intermediate Member
Username: Kd4amg
Post Number: 176
Registered: 6-2003
| | Posted on Friday, May 27, 2005 - 11:00 pm: |
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bruce...it DOES recieve, it just does NOT recieve the real weak stations at all ( say s - 3 or less as an example ) compared to another cb rig hooked up to same antenna.
Robert |
Kd4amg
Intermediate Member
Username: Kd4amg
Post Number: 177
Registered: 6-2003
| | Posted on Friday, May 27, 2005 - 11:39 pm: |
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I found in another thread ...peak out rx on a 142 tune L-13 / L-15 / L - 3. I found L-13 ( sealed with gel so it never has been touched...could not find L - 15 (or a few others ), but DID find L - 3 ( near the tx coil section of rig and I figger that when it was peaked out, that some one accidently turned L- 3 by mistake...it DRAMITICIALLY brought the "ears " up with less than a half turn of the coil.
This is what I figured was the problem from the beginning but I needed help to do what I just did get done.
If a tech wants to provide info ( or you BRUCE or any one else ) I shall return here on Saturday (tomorrow ) and see what updates have been added.
Robert |
Bruce
Senior Member
Username: Bruce
Post Number: 2731
Registered: 9-2003
| | Posted on Saturday, May 28, 2005 - 10:50 am: |
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ok so someone did a bit of tweeking ..... |
Kd4amg
Intermediate Member
Username: Kd4amg
Post Number: 178
Registered: 6-2003
| | Posted on Saturday, May 28, 2005 - 2:05 pm: |
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...yep some one stuck their GOLDEN SCREWDRIVER in it and accidently turned the EARS down a tad...L-3 in a cobra 142 is very close to the tuning coils for the tx and some one just turned the wrong one " about a half turn too fer "....NOW it has fantastic ears and talks good too.
That was what I figgered that had occurred from the beginning... this rig has had many mods to it ---
1) variable tc output from about 2 - 6 watts ) { knob on back of rig }.
2) kit in it for 40 ch below ONE and 40 more above channel 40
3) +10 kc switch for RC channels
controls for #2 & #3 are on front to right of the MIKE PLUG...
I dont need all those controls ( mostly on 38 lsb or am 15 - 20 ), but I see no need in taking all that stuff out, just leave well enuf alone.
Robert |
Hollowpoint445
Intermediate Member
Username: Hollowpoint445
Post Number: 320
Registered: 6-2004
| | Posted on Saturday, May 28, 2005 - 6:08 pm: |
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It sounds like a crystal switch modification. If so, you might gain some stability by taking it out. For AM it won't matter, but for SSB it will.
What was done to the clarifier? If it's got a lot of swing and there are stability issues, you could take it back a notch and gain some stability.
That's basically what I look for when I check out a used SSB rig. |
