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The following requirements must be followed when advertising personal antique radio / TV / audio / phono items (such as discussed in the forums here) for sale in the classifieds forum::

  • Titles must START with : FS (for sale) or WTB (want to buy) or Trade or Free at the beginning of the title..
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 Post subject: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 8:16 am 
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Posts: 8769
Location: SoCal, 91387
Need an audio output transformer for a Tom Thumb 528, coat pocket size 4 tube radio.

Their parts list shows it as TO-2123, it is fed from a 1AG4, and the secondary measures 2.2 ohms.

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 8:22 am 
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Posts: 6171
Location: Pro Tech, Philadelphia Pa.
a 10K impedence primary/3.2 secondary should work.

Now go find one, fities.

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 8:28 am 
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Location: Baldwin Park Ca.
I have a small radio shack audio output transformer maybe 3/4" square.
not sure of the value If you think It will work let me know and I will try to find it an check the values.
yours for cost of shipping .
I think it is this one (link) http://www.radioshack.com/product/index ... d=2103254#
bill

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Last edited by bills on Mar Sat 24, 2012 8:36 am, edited 1 time in total.

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 8:36 am 
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Location: Pro Tech, Philadelphia Pa.
bills wrote:
I have a small radio shack audio output transformer maybe 3/4" square.
not sure of the value I you think It will work let me know and I will try to find it an check the values.
yours for cost of shipping .
I think it is this one (link) http://www.radioshack.com/product/index ... d=2103254#
bill


That transformer only has a 1000 ohm primary - designed basically for transistor circuits.

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 8:39 am 
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RepairTech wrote:

a 10K impedence primary/3.2 secondary should work.

Now go find one, fities.

*Gasp* you mean you don't have one of these creatures floating around in your considerable stock of 1950's parts? :shock:
But thanks for the guidance on what the primary should be.

bills wrote:
I have a small radio shack audio output transformer maybe 3/4" square.
not sure of the value I you think It will work let me know and I will try to find it an check the values.
yours for cost of shipping .
I think it is this one (link) http://www.radioshack.com/product/index ... d=2103254#
bill

Thank you for the offer, Bill. If it's the one you referenced, however, they show these specs;
1,000-ohm center-tapped primary
8-ohm secondary

If you have a way to measure the impedance of yours, and it it closer to what R/T stated, please advise.

Richard

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sat 24, 2012 2:55 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 28972
Location: Livermore, CA
Hi

1AG4 has very low output, 35mw. Best to use a high impedance load, around 12,000 ohms, see spec.

http://frank.pocnet.net/sheets/138/1/1AG4.pdf

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sun 25, 2012 1:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: Rochester NY USA
I have several 10K to 4 Ohm transformers - but how much room is there?


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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Mar Sun 25, 2012 3:37 am 
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Hi Tom,
definitely not much room. The original measures 1 - 1/16 wide x 3/4 high x 3/4 wide.

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Apr Mon 16, 2012 11:02 pm 
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Joined: Jan Thu 01, 1970 1:00 am
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Location: SoCal, 91387
Bumpity bump bump, still looking for this little guy. Miniature audio output transformer, 1 x 3/4 x 3/4 inch, 1300 ohm primary to a 2 ohm secondary. Apparently about a 25.5:1 turns ratio. If you have a parts set using a 3V4 with the smaller transformer, it would work.

Will trade a Transistor radio, or pay in real money! :wink:

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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Apr Mon 16, 2012 11:59 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 23527
Location: Pocasset, Cape Cod, MA
I have a NOS UTC SO-4, rated 30k to 50 ohms which is 24.5:1 turns ratio. It's small enough (cute little thing) and probably cost more than that whole radio originally, but what the heck, I've never needed it.


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 Post subject: Re: WTB miniature audio output transformer
PostPosted: Apr Tue 17, 2012 12:26 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 8769
Location: SoCal, 91387
Thanks for the reply, Alan. Please check your PM.

I'm just wondering if a 50 ohm secondary would match up to a PM speaker.

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