| Author |
Message |
    
comptech
| | Posted on Monday, August 11, 2003 - 10:47 am: | 
|
I have an old model 29 that has little or no modulation. I had to replace two of the ferrite cores in the L14 and L16 positions because they were missing and still very little mod. what else should I relace that may be affecting the mod problem?? Any suggestions would be helpful. Many thanks |
frasiercrane
| | Posted on Tuesday, August 12, 2003 - 11:31 pm: |
|
the cores shouldn't really affect the mod much, they might not supposed to be there anyway, some coils are meant to not have cores, don't know about those specific ones.. you should be able to tell, if you lose some output power when you put them in they're probably not supposed to be there.
If you're getting good speaker audio your audio amp is working, problem would probably be in the mic amp stages, if you have a schematic and an o-scope or signal tracer you could track it down that way. I'm gonna guess that you've eliminated the mic as the problem? Is the limiter in still? Just how low is the mod? barely audible?
If the limiter is out and you've got really low audio I would suspect a bad mic amp transistor or a bad electrolytic cap. |
bruce
| | Posted on Wednesday, August 13, 2003 - 10:00 am: |
|
somewhere i remember something about a bad cap in that radios audio is the audio output ok? |
Okieoutlaw
| | Posted on Thursday, August 14, 2003 - 6:20 pm: |
|
I just had a 29 on the bench that had good recieve and no output. I got a good reply on another forum.....it was the Cap C67. It is the B+ voltage filter for the mike pre amp(tr17)and it had shorted keeping the pre amp from turning on! you may find that yours is leaking.... if you replace it...it is a 100 microfarad 10v...put a 100 mfd 16v in its place and it will keep it from doing it again! I hope this helps and I am with the response above in that I don't think you needed "cores" in the coils. If that doesn't get you going I will dig out the schematics and let you know for sure. 73's |
Okieoutlaw
| | Posted on Thursday, August 14, 2003 - 6:22 pm: |
|
By the way do you have recieve?? If little or no recieve then it would most likely be the ta7222 mod amp... |
|
