IFR Com 120A synthesizer unlocked

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4203radio
New User
Posts: 5
Joined: Wed Sep 23, 2009 10:04 am

IFR Com 120A synthesizer unlocked

Post by 4203radio »

I have an IFR Com 120a that initially wouldn't keep its generator locked much below 80 MHz nor above 995 MHz. Now it appears that the geneator won't lock below 200 MHz. I've had this problem before and all it took was cleaning connections and putting the unit back together. I've done that and still have the same problem. There are no signs of leaky capacitors. Everything else seems to work; including the receiver, function generators and, so on. My thought is there is an adjustment somewhere that needs to be tweaked? Any ideas?

I've reached out to a couple of service centers; one said send it in and, the other has yet to respond.

If nothing else, I may just sell the unit and quit fixing radios.
jry
Posts: 448
Joined: Fri Feb 06, 2004 3:14 pm

Re: IFR Com 120A synthesizer unlocked

Post by jry »

yet another weak point on the COM-120 series.

lots of different stuff fails ...assume you are talking about the first LO generate.

PM me if you want it repaired . note repairing just the module is possible by itself but the calibration may be impacted.
4203radio
New User
Posts: 5
Joined: Wed Sep 23, 2009 10:04 am

Re: IFR Com 120A synthesizer unlocked

Post by 4203radio »

I think I may have isolated the problem to an erratic connection in a plug and socket assembly or, a socket mounted IC on the control board. I took the time to disassemble and clean those connections and the 120 started working correctly; giving a cleaner output on its own display than it had been.

I live in a humid environment here in NE Oklahoma.

I’ll send you a PM as there may still be issues with the 120 and, it hasn’t been calibrated in over 20 years.

Thank You!
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