[AMRadio] Unusual transformer

K5MYJ macklinbob at gmail.com
Sun Oct 22 12:56:04 EDT 2017

The "5M-6M-7M-8M-9M-10M" is actually "5K-6K-7K-8K-9K-10K".

Bob Macklin
Seattle, Wa.
"Real Radios Glow In The Dark" 

----- Original Message ----- 
From: "Robert Nickels" <ranickel at comcast.net>
To: "Discussion of AM Radio" <amradio at mailman.qth.net>
Sent: Sunday, October 22, 2017 8:32 AM
Subject: [AMRadio] Unusual transformer

> I'm puzzling over a transformer I found in my junk, which is clearly 
> identified as a Thoardson T-21M66, but even after finding it listed in 
> the 1947 catalog online, I'm still not sure how it was used. It is 
> described as a "Matching Line to RF Load Modulation (M) Transformer" and 
> has a single 500 ohm primary (that would be the "line" part), and five 
> secondary taps that are only described as "5M-6M-7M-8M-9M-10M" which 
> must be the "RF Matching" part, but darned if I know what these values 
> are or how the transformer would be used. The audio power rating is 50 
> watts and the secondary is good for 200MA. A scan of the actual 
> catalog section can be seen here:
> https://i.imgur.com/2eyXns2.png
> I've included the multi-match modulation transformer section above so 
> you can see what the column headings refer to. Can anyone shed light 
> on what this transformer was used for and what the secondary values mean?
> Thanks and 73,
> Bob W9RAN
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