Have you tuned for maximum out or for plate and grid currents? The plate
and grid meters of a grounded grid amplifier can mislead you a great
deal when tuning. Its far more effective to tune for maximum out, then
adjust the drive for rated plate and grid currents. When you get maximum
output you will have the correct ratio of plate and grid currents.
I noticed that years ago in the Ft. Belvoir Army MARS station. One night
the S-line and 30S1 that I'd been using to work my dad was broken and
the bands to Nam were closed so I took over the new KWM2-A and Henry 2K
for my 80 meter sked. I had to back off the drive to keep it legal on
the ham band but the MARS operators (none of the hams though the
sergeant for the station was a ham and had made their tuning chart) were
accustomed to seeing maybe 200 watts out. Though the plate and grid
currents were correct for full output. I tuned it for maximum output,
and it also had the correct plate and grid currents and a solid 2 KW on
the Collins wattmeter. After my QSO, they wouldn't let me go back to the
barracks without making them a new tuning chart. The next day they
reported that the signal was so much stronger half way around the world
that it was noticed, "So you finally got the final turned on!"
73, Jerry, K0CQ
--
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.
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