Section 5.6 Operating Precautions - Henry Radio 3K Classic Mark II Operating And Maintenance Manual

With the ALC ADJUST control fully counterclockwise, tune the amplifier for
SSB operation.
Drive the amplifier to about 844 ma of plate current and
then
rotate the ALC ADJUST control clockwise until the grid current just
begins to decrease.
If the exciter can not drive the amplifier to 800 ma
of plate current, there is no need to adjust the ALC control.
The ALC circuit is designed to prevent overdrive (and therefore distortion)
from a high powered exciter.
If the exciter does not put out more than
120 watts, the ALC connection is probably not necessary.
SECTION 5.5 ALTERNATE TUNING METHOD
When you have verified the TUNE and LOAD dial settings for each band and
are more comfortable with your amplifier, the entire tuning procedure can
be completed in a few seconds.
This alternate tuning method (tuning for maximum output) requires a good RF
power meter capable of measuring at least 2500 watts at the output of the
amplifier. Set the TUNE and LOAD controls at the predetermined settings
for the frequency desired. Apply drive from your exciter to the amplifier
and bring the RF output reading to about 600 or 700 watts. Adjust the TUNE
and LOAD controls alternately to carefully peak the amplifier's output as
shown on the RF wattmeter. The amplifier will now be tuned to resonance.
SECTION 5.6 OPERATING PRECAUTIONS
Please
keep the following precautions in mind to insure safe and reliable
operation of the amplifier for many years.
Voltages inside the amplifier can be lethal. Never try to disable the pro-
tection circuits designed into the amplifier. Never operate the amplifier
with any of the panels removed.
Always tune the amplifier for resonance at the operating frequency before
transmitting.
Never switch the BAND switch while the amplifier is keyed. You will likely
have
a very expensive repair bill to replace the BAND switch if make this
mistake.
Never operate the amplifier into a load with an SWR greater than 2:1.
The componen%s in the amplifier are specifically designed for operating
parameters in line with the rated output listed in the specifications. Ex-
cessive drive causing output in excess of that specification will shorten
tube life and endanger the reliability of other components.
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