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Vintage Amateur and Military Radio Amateur/military receivers and transmitters, morse, and any other related vintage comms equipment.

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Old 13th Oct 2018, 9:49 pm   #1
G3VKM_Roger
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Default TCS Receiver Output Transformer

Hi All,

Does anyone have a AF output transformer removed from a TCS-series receiver? If so, I wonder if they could give me the resistance values of the windings, particularly the primary.

Regards

Roger
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Old 13th Oct 2018, 10:37 pm   #2
G6Tanuki
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Default Re: TCS Receiver Output Transformer

Don't worry about the DC resistance - if anything 'the lower the better' applies.

Rather, focus on the impedance-ratio/match to your intended load. The 12A6 output-bottle in the TCS8/12 is pretty much the same as a 6V6 and so you need to present a load-impedance of something around 5-7K at the anode.

The TCS I've got here - which I bought from "GWM Radio" as a kid in the 1970s - has a generic 5K-to-3-Ohm output-transformer which I fitted in place of the original (which was designed to drive a 500-Ohm load). The transformer in question I actually salvaged from a radio I found dumped in a stream near Ivybridge in Devon while on holiday with my parents. [I got a 6AT6 and a couple of other valves from it too].
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Old 14th Oct 2018, 10:55 am   #3
G3VKM_Roger
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Default Re: TCS Receiver Output Transformer

Many thanks for the comments. I'm fairly sure that the primary winding of the TCS transformer is O/C but I just wanted to check that it wasn't some very thin, high resistance wire in use. I've used an AVO8 to check and can't get any reading, which is fairly conclusive, I feel.

I have a couple of generic valve output transformers here which will do the job, including one I bought for use with an HRO receiver, so I will be trying one of those. Next step is to find out if another fault took out the original iron!

All the best,

Roger

Last edited by G3VKM_Roger; 14th Oct 2018 at 10:56 am. Reason: add
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Old 14th Oct 2018, 11:37 am   #4
G4XWDJim
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Default Re: TCS Receiver Output Transformer

Roger,

I do have one of these transformers I'm sure but it's buried in one of 6 really heavy boxes of transformers and my strength ran out before I could find it.

However, my TCS 12 instruction book on page 99 states:- T201 Primary 7500 Ω, Sec. 500 Ω CT. 2.4 W 200-5000 CPS. Part No 677N227.

When I was playing with TCSs I found that almost any average audio output transformer was ok assuming you wanted to drive a speaker. Hope this helps, sorry I'm a bit late.

Jim
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Old 14th Oct 2018, 2:46 pm   #5
G3VKM_Roger
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Default Re: TCS Receiver Output Transformer

Hi Jim,

I'd just found the spec on the transformer but thanks for confirming it. I think a lot of these items failed during the life of the set. I do have a couple of others I can try, so will not bother you with digging out an original.

Hope you're well,

73

Roger
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