Icom 751A...distortion after an hour?

[W9WD]

I am looking at an Icom 751A but it has a problem. I am wondering if it is a common problem with (hopefully) an easy fix. The owner says this.....


"The audio becomes distorted after about an hour of operation and you have to turn it off for about 15 minutes for it to restore itself."


Anyone heard of this?

Thanks

 

[W5LZ]

I don't remember that as being all that common. Sounds a lot like too much heat for some reason. There can be quite a few reasons for that, so won't guess about it. There's a very common reason, deals with the radio having been modified. Care to guess what that modification was??
- 'Doc

 

[W9WD]

Could be.
The radio belongs to the club. Don't know where it came from originally. Probably the club didn't modify it, but if someone donated it, they might have.
Even if it didn't have this issue I would probably have it gone through and straighten up and tuned anyway.

 

[W9WD]

After talking with a couple of repair places (one of which was Icom) they both say the same thing.
I guess there are some trimmer caps that were plastic and tended to drift which sends it into oscillation. They replace the caps with ceramic ones and that is that.

All it takes is money

 

[W5LZ]

Our local club is 'blessed' with a 751' too! Most of the people in the club are just not very familiar with HF, and the 751' being an 'older' radio doesn't 'work' like any of the newer ones (menus, etc.) so I sort of doubt if it'll be a huge favorite, you know? (The other HF radio is one I'm very familiar with so would be my first choice anyway.) We're also not 'blessed' with the manual! Can you imagine how much fun that is ??
- 'Doc

 

[W9WD]

I found a manual on line last night. If you want I can email it to you.

 

[W5LZ]

No, don't go to any bother. If the 'custodian' feels we should have a manual I'll bet he can find one fairly easily on the internet. He's one of the only ones who has any experience on HF, but not real recently, sort of. He's also the one who has the radio and I figure he'll get one sooner or later . I want his 'job' like I want a kidney stone!
- 'Doc

 

[N8YX]

VCO trimmer caps are shot. Easy fix, but practically every one of the HF radios Icom produced in this time frame seems susceptible to the problem.