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Title: Input transformers Post by: Detroit47 on June 21, 2012, 05:53:49 PM I came upon a box of transformers in my travels. Some of which I have no data on. I have Three McMartin MT-4 transformers the also say 2-A-78 23045 on the side. And several Newcomb TR-91 input transformers no data except pri 50/200 ohms sec to grid. There is also a couple of small potted ones labeled MT23 AG. They were all in a box marked audio transformers. Any data would be great .
Thanks John N8QPC Title: Re: Input transformers Post by: KA2DZT on June 22, 2012, 02:25:53 AM The 50/200 probably has two input windings. In series you get 200 ohms, in parallel you get 50 ohms.
Then your high impedance secondary winding which you connect to your grid, other end grounded. Fred Title: Re: Input transformers Post by: Opcom on June 22, 2012, 09:04:13 PM The one or two of those house brand units I have had open makes me believe they were made under contract by one of the larger manufacturers. A McMartin one looked very much like an Altec one. It doesn't matter so much as those should be quality USA made stuff, use them in good health!
Title: Re: Input transformers Post by: Detroit47 on June 23, 2012, 01:10:39 PM I am going to take pictures of them. I have some other ones with no markings on them. They look like balanced to unballanced input transformers that i have seen before.
John Title: Re: Input transformers Post by: KE6DF on July 17, 2012, 04:45:09 AM Someone listed a McMartin MT-4 on ebay. AMfone - Dedicated to Amplitude Modulation on the Amateur Radio Bands
They included the following pin out data: "The MT-4 parameters are: Pri: 1-4: 600R, 1-3: 50R; Sec: 3-8: 10K, 2-8: 60K" http://www.ebay.com/itm/VINTAGE-MCMARTIN-MT-4-MICROPHONE-AUDIO-INPUT-TRANSFORMER-/251109747531?pt=Vintage_Electronics_R2&hash=item3a774eab4b |