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I broke so called 'IF transformer' on my radio. I was just slightly trying to regulate it to follow an instructions that is found on Wikihow page. My aim was to listen to the conversations of pilots from the airport we have near our house.

Anyway, I cannot find a transformer with the same size (5.7mm X 5.7mm). The radio still works. How important it is to replace it? I will go to a place where electonic components are sold and I don't know if I should accept if they offer a transformer with slightly bigger size(7.9mm X 7.9mm)?! Maybe I can use wires to mount it to the board?![enter image description here]1

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  • $\begingroup$ How do you know that the transformer is broken? If the radio still works, then the transformer might not be broken. $\endgroup$ – rclocher3 Sep 18 '16 at 18:46
  • $\begingroup$ Top piece where you turn to regulate it (like a screw) was broken into pieces. So I cannot set it to default anymore. In other words, I cannot operate it. $\endgroup$ – Karel Capek Sep 18 '16 at 20:21
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    $\begingroup$ These small transformers are not meant to be adjusted in normal operation. As you see, the ferrite parts are fragile. If the radio is not operating acceptably, you could try a different transformer, using wire leads if necessary. Not all transformers are designed for the same impedance values, so you can't be sure, but it might be worth a try. $\endgroup$ – Martin Ewing AA6E Sep 22 '16 at 0:33
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Chances are you can find what you need here.

http://www.digikey.com/product-search/en/inductors-coils-chokes/adjustable-inductors/196629?k=toko

Could be you broke the slot without moving the coil core. If that's the case you might be better off to leave it alone.

If you can solder and want to replace it you need a voltmeter and a schematic. Put the voltmeter on the AGC line. Tune to a station. Adjust the core for maximum AGC reading on the meter. If you do replace the transformer you should get an alignment tool or a plastic screwdriver to prevent damaging the new transformer's core.

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The transformer is most probably a part of a critical tuned circuit. If the ferrite is broken then the radio keeps working but the filtering is worse. There a a number of ways to find a replacement for the transformer.

1: Try to get the technical manual and find the partnumber and supplier (manufacturer)

2: Look for the information on the pcb and try to find that on the internet

3: Look for the information on the transformer body and try to find that part on the internet.

Tuning an if circuit should be done with a sweep generator/ spectrum analizer. Otherwise is is very difficult to find the correct critical tuning position. Also a technical manual is to be preferred.

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