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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 20th Sep 2023, 12:03 pm   #21
Station X
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Default Re: RF gain control on AR88 not working

Good to know it's working again. Be sure to make a good job of resoldering R56 or you could be saying goodbye to your output transformer should you use the set with headphones.
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Old 20th Sep 2023, 3:45 pm   #22
Radio Wrangler
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Default Re: RF gain control on AR88 not working

But before a new problem arises, have you done the due diligence on the DC blocking and tone correction capacitors?

Sorry for pestering but any of these wonder-components can destroy your audio output stage, both valve and transformer with a fighting chance at taking out the mains transformer. Now is the exact time you would want to travel back to after the event, if you could hitch a ride on a passing time machine.

David
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Old 20th Sep 2023, 6:34 pm   #23
G6Tanuki
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Default Re: RF gain control on AR88 not working

And while you're in there, consider doing my output-transformer-saving mod using a couple of wire-ended NE-2 neons across the primary too....

Neons are cheap; replacement output trannies for the AR-88 are not.
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Old 21st Sep 2023, 12:49 am   #24
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Default Re: RF gain control on AR88 not working

You also need to find out why the negative bias voltage is so high.
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Old 26th Sep 2023, 10:54 am   #25
Alan Bain
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Default Re: RF gain control on AR88 not working

In case anyone finds it useful - here is a clear scan of the CR88 wiring diagram. I have no idea where this came from originally as when I was fixing my AR88 I had to rely on the hard to read one from BAMA.

This morning the cat knocked down a file which contained details of projects I had worked on long ago as a student and in it there was an AR88 manual and this original sheet of wiring diagram.

Uploaded as zip to stop resolution being reduced!

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