Hello!
I'm trying to repair a Sommerkamp(Yaesu) FL-50B. It does power up and transmit
but the output power is just 13W. I tried to replace final 6JS6C without any
adwantage, also replace the driver tube with same result.

The B+ is 350V, dropping to 325V while transmitting... Already tried to
exchange the plate voltage filter condenser, but apart slightly minor ripple,
no result in power output increase.

The transmitter is fully tuned, by me who may be not the best man for that,
but hovever, I have a good oscilloscope and anyway, the power output before
tuning was a (little little) less.

The antenna relay is ok. By measuring with oscilloscope the grid of the
6JS6C, I notice increasing in signal amplitude while rotating full scale
"carrier" control from 0 to 8. After 8, signal no more increase and there
is a little derive in 5.12.. Mhz carrier frequency. I think this is normal
for this kind of transmitter. The strange fact instead is that despite
driver signal is increasing, output power no further increase after carrier
control position 4.

I have regulated bias to 60mA, I suppose it's good for 6JS6C, I have not the
manual of the transmitter so I don't know exactly. Anyway, this has no
strong influence over power output. While at full power, I never see IC
more than 125mA, that's half the scale of the instrument. In PO measure,
it signs slightly more than .2

Well, no more. Someone who has more experience than me, please give me
his help!

....and also, I need to know what's (in Vpp) the right output of the carrier
quartz oscillator measured at the input of the balanced modulator.
While tuning, I forgot to record the previous amplitude... Now, if I recall
correctly, is 2.5Vpp... More than 3.5Vpp, the oscillator become unstable and
may not start oscillating, less than 2.5, output power further decrease...
So I may be right, but I would like to know if there is an exact value to
regulate on.

The power is more or less the same in every band, I use an FR-50B as VFO,
but with a 9MHZ quartz I have, the results are unchanged. All measure are
on a 50R dummy load with wattmeter. A Osker Block SWR/Wattmeter inserted
hovewer sign the same output and no SWR.

Ciao,
AB