[Boatanchors] Collins 75S-3C audio output transformer

[Richard Knoppow]

    I read that you found a replacement. However, before discarding the 
old transformer check that there is not an open at the connection from 
the internal winding to the external connection. I don't know if Collins 
used transformers with terminals or wires but it doesn't matter, in 
either case the internal winding is soldered to a terminal and these can 
go open. Often easy to fix.

On 4/26/2026 9:59 AM, n2lxm--- via Boatanchors wrote:
> Greetings All,
> 
>          While setting up my new operation position, I found that I had no
> audio from the receiver. I pulled it to the bench and found that the
> audio transformer has an open primary. Trying to find and information on
> the transformer(primary impedance) has come up short. Tried NSN
> 667-0302-000, found plenty of E-bay hits, but no spec's. Dose anyone know
> what the primary impedance is. The tube data for the 6BF5 shows class 1A
> as 12 K, which seems a bit high. I pigged tailed an old AA5 output
> transformer in and it works. And help would be greatly appreciated.
> 
> 
>                                                             N2LXM
>                                                           American
>                                                             Patriot
>                                        Proud Father of Two U.S. Marines
>                                                          Semper Fy
-- 
Richard Knoppow
Los Angeles
WB6KBL
SKCC 19998