[ARC5] Command Set Receiver Audio Transformers REV-1

[Tim]

That's some really excellent work Bill!  Well done!
Thank you...
Tim
N6C

On Thu, Mar 26, 2026 at 10:29 AM Bill Cotter via ARC5 <arc5 at mailman.qth.net>
wrote:

> Hello all,
>
> Attached is the first revision of Command Set Receiver Audio
> Transformers paper I compiled while trying to figure the
> differences in about 20 of these old receivers. Included are actual
> measurements to confirm what has been found in the literature.
>
> Addition, corrections, and criticisms welcome.
>
> 73 Bill N4LG
>
> ==================================================================
>
> I have been in the process of repairing and upgrading several old
> command set receivers with the goal of getting a stack of these
> functioning on 160M, 80M and 40M. And, eventually getting the
> matching transmitters back into working condition.
>
> One thing that has bothered me over the past month are all the
> differences in audio output transformers that were used in these
> radios. My goal was to get them all set to work with 600Z output.
>
> After digging through a lot of tech manuals, conversion manuals and
> magazine articles, I have figured out what I didn't understand
> about the types and choices of the output transformer used in all
> the common sets. When I go through the process of researching
> everything about a topic, I compile my notes for when I forget down
> the road, hi!
>
> Attached are my notes on the BC-4XX and ARC/R-2X receiver audio
> transformer options. Hopefully, these notes can save someone else
> from a lot of head scratching.
>
> Any comments, corrections, contributions, etc are welcome.
>
> 73 Bill N4LG
>
>
> ______________________________________________________________
> ARC5 mailing list
> Home: http://mailman.qth.net/mailman/listinfo/arc5
> Help: http://mailman.qth.net/mmfaq.htm
> Post: mailto:ARC5 at mailman.qth.net
>
> This list hosted by: http://www.qsl.net
> Please help support this email list: https://www.qsl.net/donate.html
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/arc5/attachments/20260326/d2c9c6e8/attachment-0001.html>