[Yaesu] Intermintent FT-5100 UHF PA

[Bill Miner]

Nate,

I have heard of symptoms like yours and the trouble was internal to the
PA
module.  A friend was even  able to dig into the module and repair a
problem on the substrate.  If you can get (or make) an RF voltmeter you
could compare input and output signal levels along with checking bias
voltages etc. It should be possible to isolate the trouble to the module
or control circuits.

Good luck.
73,
Bill - K6WLM

Nate Bargmann wrote:
> 
> Hi all.
> 
> My FT-5100's UHF PA has been acting strange of late.  The power output
> is intermintent going from full power in either high or low setting to
> about 250mW on the next transmission.  Since it will do 30+ Watts out,
> I'm assuming the PA module is in good working order.  So, I'm suspecting
> the problem may be in the control pots of VRs 1001, 1002, and 1003 as
> they may be dirty.
> 
> I would most appreciate help from anyone who has a service manual who
> is willing to  help me troubleshoot this thing a little closer and
> provide the realignment procedure for the PA.
> 
> Thanks!
> 
> 73, de Nate >>
> 
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