[Kenwood] TS-50 problem

[Steef PA2A]

Chuck,

the 10 and 50 watt levels can be adjusted by variable resistors but 
there must be some problem in the bias circuit of the finals where the 
power level is set by fixed resistors. A cold solder joint or a changed 
resistor value can be the cause of the changed bias.

The 2SC5894 's can dissipate 250 watts of heat each so 200 Watts is no 
problem for them except ferrite transformers will run a bit hot. In SSB 
increased intermodulation products can appear but in CW there is no big 
problem. The TS850 has the same amplifier and running 180 Watts in CW 
was no problem.

73s Steve PA2A

chuck via Kenwood schreef op 2018-08-05 00:59:
> I have a TS-50 that I recently brought back on line and found that
> everything worked...….except the output power into a 50ohm dummy load
> was a whopping 200 watts.  I immediately stopped, went to SSB mode and
> whistled up 200watts.  A quick try in CW and AM produced the same
> results.
> 
> I had this rig repaired a few years back by Clif @ AVVID.  He put it
> in tip-top shape and I used it periodically afterward.  Fast forward
> to now (3+ years later) when I got it from the closet and found the
> above described problem.  It's been in a controlled environment and
> not subjected to humidity or high temperatures.
> 
> I'm guessing an electrolytic has given up and the bias on the finals
> is in trouble.  But that's only a guess.  Anyone wish to comment?  I'm
> not equipped to service it unless there is something obvious that
> doesn't require precision work.  I'm one of the dinosaurs who is
> linked to BA gear where I still do my own repairs, etc.
> 
> Thanks for the read.
> 
> 73 de W4MIL
> Chuck
> 
> 
> 
> 
> チャーリー ミルトン
> 
> 
> 
> 
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