[R-390] R-388 question?

[David Olean]

That is a common conversion of the pentagrid mixer for a dual triode 
mixer for lower internal noise. I believe it is documented in the 75A4 
compendium that is offered by Electric Radio. I believe that it 
originated in a Ham Radio Magazine article in the 1970s. I did the same 
thing to my 75A4 and it worked great.

Dave K1WHS

On 9/23/2022 6:59 PM, John Gedde wrote:
> Hi folks,
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> Long time no post.  I hope I'm not crossing a line asking a R388 question, but if anyone knows the answer, it'd be this group!
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> I just acquired a Collins R388.  V102 has been changed from a 6BE6 to a 6DJ8.  It was a not a trivial change since the 6BE6 is a 7-pin tube and the 6DJ8 is 9-pins!!  Looking underneath, you can't tell it wasn't done by the factory (it wasn't.)  The workmanship of whomever made this mod is superb!
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> I have only found one reference alluding to this mod in a forum post from 1997.  The poster said he had documentation of the change so this mod must be a 'thing.'
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> Any ideas!
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> 73
>
> John AD2DK
>
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