[ARC5] Line-transformers to replace shot audio transformers

[Kenneth G. Gordon]

On 30 Sep 2016 at 12:10, Robert  Eleazer wrote:

> I see that Fair radio has "Pico Low Level Audio Transformer 10K ohm to 1.2K ohm"   It is quite 
> small.  Might that be close enough to work for a high impedance output?

Hmmm....that might. I'll review the output audio transformer specs in the service manuals I 
have here to see. Nominally, the output impedance of a 12A6 according to the RCA 
manuals is 7500 ohms, but that varies somewhat with external circuit parameters.

The 10K primary would most probably be OK, but that 1.2K secondary may be a problem. 
The normal output impedances for the receivers was originally something like 4K ohms and 
300 ohms, then 600 ohms.
  
> And do y'all think it would be a good idea to inject something into the original transformers to try 
> to stop any corrosion?  Such as LPS-1 or ACF-50?

Well, the cans are full of beeswax, so injecting something like that above may not work very 
well. I am going to dismantle one of my failed transformers to see what I can find.

> Finally, are the Type 12 and similar less-venerated postwar ARC sets a possible source of 
> parts?

Possibly. As McVey states, their output impedance was 600 ohms.

>  Specifically, I am wondering what I will find inside the ARN-30 instrument driver I was 
> given.  It is clearly a source of covers and possibly a replacement chassis, but maybe there are 
> some other useful parts in there.

Hmmm...maybe. Anyway, let us know whatever you discover in this matter.

Ken W7EKB

> Wayne
> WB5WSV 
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