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Success Stories If you have successfully repaired or restored a piece of equipment, why not write up what you did and post details here. Particularly if it was interesting, unusual or challenging. PLEASE DO NOT POST REQUESTS FOR HELP HERE!

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Old 19th Jul 2015, 9:28 am   #1
lesmw0sec
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Default TS-530SP repair.

Was asked to look at a Kenwood transceiver which was described as being 'deaf'. An understatement, as the sensitivity was about 50dB less than the spec.
Traced the loss to the front end and the signal was being reduced across a little step-up transformer in the Aerial circuit. This had continuity and I could not believe that this was the real cause however, as Holmes said "When you have eliminated the impossible..."

Removed it and was surprised to find the windings fused by heat. Some bright spark must have connected a transmitter to the ae. input! Having re-wound it with a shaky hand and much magnification, it worked well, but still not quite up to spec. Then discovered that all the IF cores had been tweaked...

What really amazed me was the fact that the mosfet RF stage had survived.

You would have thought an amateur radio operator would have had a bit more sense!

Les.
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Old 19th Jul 2015, 9:45 am   #2
Radio Wrangler
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Default Re: TS-530SP repair.

You would, but there are always exceptions. Generally, the worst HF transceiver repairs are those where some naughty CBers have tried to modify them to transmit on illegal frequencies.

I once held up the mutilated remains of an LO mixer/filter board and announced:

"It was the Marx Brothers, in the kitchen, with the blowlamp"

For some reason they are most attracted to Yaesu.

David
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Old 19th Jul 2015, 10:20 am   #3
G6Tanuki
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Default Re: TS-530SP repair.

Rather than someone having transmitted into the front-end, could it have been caused by a loss-of-earth on something connected to the aerial input? I've seen various instances of this over the years - an accessory [transverter, preamp, linear] and transceiver powered from the same DC power-supply - if either device loses its earth then the power-supply current can flow through any suitable path back to earth.

Can lead to cooked antenna coils, burned-out loudspeakers, and in one instance a microphone 'curly cord' that became curiously stiff because all the wires had fused together.

[A similar thing sometimes happens on vehicles where the engine earth strap fails and the handbrake/clutch/throttle/choke-cable forms the earth return for the starter motor].
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