Anytime the TS-520 does not putout 100 watts keydown into a 50 ohm load
,IT IS BROKE,BROKE, Look at it this way,, 160 watts input at 65%
effeciency = 104 watts output..On HF, 160 thru 15 meters 60 to 65 %
eff. is normal..A service monitor calibrated for VHF/UHF may be a bit
off at HF freqs..It happens .. Hal

Anytime the TS-520 does not putout 100 watts keydown into a 50 ohm load
,IT IS BROKE,BROKE, Look at it this way,, 160 watts input at 65%


Then why does Kenwood, the manufacture, have lower numbers in
their service manual?

I did some testing on my TS520S. With 200ma plate current it produces
about 80 watts on the low bands which is spec. If I crank up the drive
and exceed the 200ma plate current spec, I can get 100 watts on some
bands, but not all bands (like 10m). How long will my tubes last if
I exceed the 200 ma spec? I don't know and its not worth the risk
for a fraction of an S unit.

I looked in a 1992 ARRL handbook. They spec the efficiency of a class
AB amp at 50%. (see section 15). 50% of 160 watts is 80 watts which
is exactly what I am seeing on my radio.

Say what you want. I believe the service manual.

chuck