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Author Topic: Help - Yaesu FT-920 problem  (Read 218 times)
W4PBU
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Posts: 86




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« on: December 01, 2008, 07:09:43 PM »

A torroid inductor in the main tuner unit burned up.
It is loctor # L5006 Yaesu part # L0021978
I talked to Vertex today but the rep could not help me with any possible reasons for this part burning up.
I was not using the radio when this component burned up, although I may have inadvertantly left the radio on in the receive mode for about 36 hours before coming back into the shack and discovering the terrible smell I don't know what caused it.
The radio still works with full output but the rep said that he was not sure what frequencies that particular inductor was associated with but that the radio would probably not work on those freqs.
The tech rep suggested that it probably burned up as a result of some other part failure but could not offer any help as to what that might have been.
The inductor is only $3.30 but no sense replacing it until I find out why it went bad in the first place.
Has anyone else ever had this problem?
Any help would be greatly appreciated.
Thanks
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WA3SKN
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Posts: 5443




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« Reply #1 on: December 02, 2008, 03:07:38 AM »

Inductors don't just "burn up"!... some other failure caused excess current to flow through the inductor.
Do not replace the inductor til you find what caused the excess current, probably a shorted capacitor.
73s.

-Mike.
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K0BG
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Posts: 9846


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« Reply #2 on: December 02, 2008, 08:11:57 AM »

Just replace it and carry on. The reason it failed could be a number of things, but keep one very important point in mind. The tuner is designed to match up to a 3:1 SWR. It might do a little better if the phase angle isn't too severe, but it's still a limitation. Here's an example.

If you happen to be using an G5RV, this limitation means the built in tuner could be operating at it's matching limit near the 80 meter band edges. If this is the case, the inductor could get hot enough to fail.

Alan, KØBG
www.k0bg.com
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