[Kenwood] TS-520SE: Distorted audio/low SSB power out

[Dr. Gerald N. Johnson, electrical engineer]

Unless you have a peak reading wattmeter, 15 - 20 watts isn't out of
line for AVERAGE power on SSB. You can only check peaks with a scope or
a peak reading wattmeter. That ratio of peak to average depends a lot on
the voice and the microphone. If you have distortion on voice its
probably from trying to drive it too hard. Watch the ALC meter and just
tickle the ALC (not beyond half scale) and your distortion should go
away. ALC is derived from the peak output.

No matter how loud you shout, the peak power on SSB won't be more than
the CW power, the PA tubes just can't supply higher peaks.

It is possible that bad PA tubes, or improper bias will add distortion,
and possible that a leaky coupling capacitor in the audio section or a
badly biased stage most anywhere in the transmitter can introduce
distortion. Check the PA idling bias, the PA plate current on SSB
without drive should be about 40ma for a pair of 6146. More will lead to
less PA distortion but melted tubes from excess power dissipation, less
will lead to more PA distortion.

73, Jerry, K0CQ

-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.