Aug 26
The D200 PA went up in smoke when switching it on. I sold it then for good money and purchaed a used Mirage B1030G 300w+ transitor PA which is hopefully a good replacement.

Not only this below - now the IC820 VHF rig developped a fault. But after cleaning all flat wire contacts it is working again.

After the TS690 my D200s 2m PA had a big bang without being switched on !! PCB tracks seem to grow ... and sometimes they contact each other. I do not know the reason, but the was a short circuit between two tracks of the mains leads on the board. I had to clean all that, because it looked like a major explosion to have happened there and replace the tracks by wires. Voila the amplifier is running again.

My Kenwood TS690s developped an error in the IF chain. It looked like a defective IC (TC9174F) which is hard to get nowadays. The integrated circuit is a serial/parallel controller which switches the 455 kHz filter bank. But it turned out to be the Murata 455kHz filter (CFW455F - 12kHz BW). I removed it and the radio is working well - no 12 kHz filter available. As soon as I have the replacement the box will be repaired. I have never seen before such a filter going mad.

Update: The fault returned - it does not seem to be the filter. I desoldered the two double switching diodes. Now the rig is working again, but no AM and FM possible. I try to get the TC9174F IC now for replacement.

Posted by Christoph Petermann

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