The AM Forum

Was wondering if anyone might know where I could find the terminal hookup sheet for a
Thordarson T-21M61,-- 60 watt multimatch modulation transformer.

I have such a sheet for a CVM-1 Stancor 30 watt transformer, and am sure there must be
a similar sheet for the Thordarson indicating the "pinout" for various tube impedance matches.
Any help would be greatly appreciated.

                                                73, K1MVP
                                   

I went through my pile of documentation but came up dry for that. I am using a Thordarson CHT 300 watt multi-match in my 811 rig and if I recall correctly, the connection information is inscribed on the cover. Guess they overlooked that luxury on the T-21M61. The only information that turned up in my bookmarks was here:

http://www.amwindow.org/tech/htm/modtran/thordarson/thordarson1.htm

and also here:

http://www.bunkerofdoom.com/xfm/index.html

The bunkerofdoom does have quite a bit of Thordarson information in the format of their service guides and catalogs. Might be worth browsing the pdf archives there.

Are you sure the T-21M61 is a multi-match transformer? The reason I ask is that the 21Mxx series of transformers listed at the first location are all fixed impedance transformers.

Good luck in your search!

Rob W1AEX

Ah, looks like you are right, it is a multi-match. It shows up on page 11 of the 1949 catalog located here:

http://www.old-radios.com/Documents/Thordarson1949CatalogFinal.pdf

It does not give much information other than the current ratings with the secondary in series or parallel.

Rob W1AEX

Rob,
Thanks for the info,--I did come up with an "info sheet" on some older Thordarson multimatch
transformers, of different wattage ratings, which may help.
I am going to attempt to establish the windings ratios by injecting a low level audio frequency
and measure the various voltage ratios to see how it comes out with the info that I have on
some of their previous multimatch transformers.
                                                 73, Rene, K1MVP

Sounds like you are on your way Rene. Good luck with the project!

Rob W1AEX