Repair IF transformer in 39-6 - Printable Version
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RE: Repair IF transformer in 39-6 - Radioroslyn - 03-15-2019
L= inductance C=capacitance and F= frequency. 470kc is the IF frequency for this set.
RE: Repair IF transformer in 39-6 - mikethedruid - 03-15-2019
Yes, there IS a meter for that. This one can be used to measure cpacitance, inductance, and resistance.
https://www.ebay.com/itm/LCD-1999-BM4070-LCR-Meter-Self-discharge-Capacitance-Inductance-Resistance-US/232307982507?epid=3018754128&hash=item3616a280ab:g:jvAAAOSwvMVcdNWj
hope this helps.
RE: Repair IF transformer in 39-6 - mikethedruid - 03-15-2019
Also, as Mike (Morzh) said, to be successful in this hobby one really needs to acquire a good understanding of basic electronics. I strongly suggest the book Audel's Radioman's Guide. It can be had reasonably from Amazon. Any of the older (pre 1960) editions are good for what we need for this hobby.
https://www.amazon.com/Audels-New-Radiomans-Guide-Anderson/dp/B001Z75WCI/ref=sr_1_5?keywords=Audel%27s+Radioman%27s+guide&qid=1552666270&s=gateway&sr=8-5
RE: Repair IF transformer in 39-6 - Ron Ramirez - 03-15-2019
Mike the Druid
Thanks for that link to the LCR meter! I think I should pick one of those up. It might serve me well for those pesky Philco coils. Edit: Ordered.
RE: Repair IF transformer in 39-6 - morzh - 03-15-2019
https://www.ebay.com/itm/Stanford-Research-SR720-LCR-Meter-Multi-Frequency-Impedance-Meter-With-Adapter/223391955468?hash=item340332ba0c:g:hsoAAOSwFfJcZc5-&frcectupt=true
I have this.
Got it for free.
RE: Repair IF transformer in 39-6 - Stonewall - 03-16-2019
If you only broke off one of the leads to the coil, it is quite possible to very carefully, with a good magnifying device, find the broken end of the wire in the coil. I've done it before using a jeweler's loupe and a dental probe. Then you may be able to unwind just enough of the wire to reach a connection point or connect to a new lead. Twist the tiny wire around the connection point and heat with a very hot soldering iron, then apply solder. If the soldering iron is sufficiently hot, it will melt off the insulation; trying to scrape it off is very difficult. If you only unwind an inch or two, the change in inductance and resistance will not be problematic.
RE: Repair IF transformer in 39-6 - rfeenstra - 03-16-2019
I ordered one too!
RE: Repair IF transformer in 39-6 - Jake Blake - 03-17-2019
Thanks for this advice.... I bought new prescription eyeglasses after I made my boo-boo. I'll get a magnifying glass also.
RE: Repair IF transformer in 39-6 - Jake Blake - 03-17-2019
Somehow, I did not realize there were hand-held meters out there that measure inductance..... That is VERY tempting, more-so for my loudspeaker work . I believe I'll get that. Thanks
RE: Repair IF transformer in 39-6 - Jake Blake - 03-17-2019
Incidentally Stonewall ,
. . . . the insulation on that tiny wire is fiberous, . . . not rubber or any kind of plastic. It was this fiberous stuff that made me think I was just picking out a piece of lint or debris out of the chassis. I couldn't see it well-enough to realize it was a conductor with cloth insulation. Thanks again for your magnifying glass suggestion.
Jake
RE: Repair IF transformer in 39-6 - Radioroslyn - 03-18-2019
Typically it would be silk or cotton.
RE: Repair IF transformer in 39-6 - morzh - 03-18-2019
All natural
RE: Repair IF transformer in 39-6 - Jake Blake - 04-16-2019
(03-15-2019, 12:04 PM)mikethedruid Wrote: Yes, there IS a meter for that. This one can be used to measure cpacitance, inductance, and resistance.
https://www.ebay.com/itm/LCD-1999-BM4070-LCR-Meter-Self-discharge-Capacitance-Inductance-Resistance-US/232307982507?epid=3018754128&hash=item3616a280ab:g:jvAAAOSwvMVcdNWj
hope this helps.
I got the meter. Thanks again Mike!
Neat little thing...it's already told me one of my coils I have in my speaker crossover stash is worthless.
RE: Repair IF transformer in 39-6 - morzh - 04-17-2019
It's just trying to make you toss all your coils and buy new one made in China. Cause it itself is made in China.
RE: Repair IF transformer in 39-6 - Jake Blake - 04-18-2019
(04-17-2019, 01:39 PM)morzh Wrote: It's just trying to make you toss all your coils and buy new one made in China. Cause it itself is made in China.
Oddly-enough, that is not true for these specific coils....these were probably wound right at the location
where I bought them from : Highland Heights, Ohio. This one , I thought, was around .5mH, but turned out to be .28 mH. ( I say 'thought' because I've removed wire from it in a guessing game). This resulting value would only be good for a crossover point of about 5kHz , . . . too high for my preference.
But your point is well-taken. :-) I know a few capitalists that are not beyond such things.
Surely, you're not suggesting these little cardboardy ones in the radios were made in China in 1939 either.
The new IF transformer I bought as a possible replacement has an fragrance of Moo Goo Gai Pan,
and measures 8.22 mH for the primary, and .185 mH for the secondary.... sure hope that secondary is high enough. It's tiny.