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Components and Circuits For discussions about component types, alternatives and availability, circuit configurations and modifications etc. Discussions here should be of a general nature and not about specific sets.

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Old 10th May 2022, 4:41 pm   #1
Alan_G3XAQ
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Default Red dot beside IF transformer pin

With the generosity of friends and forum members I have collected together several valve-type 465KHz IF transformers for a homebrew project.

Several of them have a red painted dot beside one of the four pins. My guess is this indicates the HT connection? So the other end of that winding goes to the anode. The other two will be the secondary (input winding) for the following stage.

Question is: does it matter which way round that input winding is connected? I suppose it might be argued it is best to place the active (grid) side of the secondary winding as far as possible from the anode side of the primary, to minimise capacitive coupling, but I'm open to other better informed guidance.

Thanks,

Alan
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Old 10th May 2022, 4:51 pm   #2
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Default Re: Red dot beside IF transformer pin

It represents something

Only the possessor of a data sheet ca tell just what.

David
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Old 10th May 2022, 6:03 pm   #3
ms660
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Default Re: Red dot beside IF transformer pin

I'm not sure with the valve ones but with the Weyrad transistor ones (P50 series) the Red dot was to indicate the pin number sequencing clockwise from the Red dot.

Lawrence.
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