The PHILCO Phorum
Open I.F coil - Printable Version

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Open I.F coil - lasurveyor - 08-01-2016

Hi,
I have a M Ward 62-319 that went dead on me. Doing some signal tracing I found the suspect 2nd I.F. transformer and in it an open coil. What do I do with this?? Finding an exact replacement would seem impossible. Does someone rewind these things for a reasonable cost? I removed the can so I could check the coil itself finding it open and no visible wire break.
Thanks,
Alan

RE: Open I.F coil - Radioroslyn - 08-01-2016

Hi Alan,
Well there's a few choices. Hunt down a 465kc IF output transformer, try Play Things of the Past. Back in the day there where companies that make replacement IF transformers. Or If you have a slug tuned 455kc can you can use it but you'll need to open it up and change the value of the internal tuning caps to get it to resonate at 465kc. Or you could use a rf choke in place of the secondary coil and a small cap connected to the plate of the IF amp tube to coule the signal over to the diode plate. This will make the if rather broad and will loose some gain.
Some of the older Philcos have 460kc if cans you maybe able the get one to go up to 465

RE: Open I.F coil - lasurveyor - 08-01-2016

Thanks for the response Terry. So as long as it's a 465 kc it should do the job?  And something close may be able to be tuned to 465 simply with the padders?

Alan

RE: Open I.F coil - Radioroslyn - 08-01-2016

>So as long as it's a 465 kc it should do the job? 
Your a little better off if it is a output transformer.The secondary has a low impedance to match the diode load. The input transformer secondary matches the grid of the IF amp tube which is high impedance.
> And something close may be able to be tuned to 465 simply with the padders?
That's why I mentioned the 460 and the 470kc Philco transformers.

GL

RE: Open I.F coil - kc5gym - 08-11-2016

I have used this method of bypassing before; it works pretty well.
   
Here is the link to the writeup.
http://antiqueradios.com/chrs/journal/transformers.html
I have also carefully unwound the open coil, made the repair, and wound the wire back on.

RE: Open I.F coil - lasurveyor - 08-11-2016

(08-11-2016, 06:28 AM)kc5gym Wrote:  I have used this method of bypassing before; it works pretty well.

Here is the link to the writeup.
http://antiqueradios.com/chrs/journal/transformers.html
I have also carefully unwound the open coil, made the repair, and wound the wire back on.

This looks great, I'll try it. Thank you!!