The ACOM is 0 to -11volts, if my memory of conversations w/the gang
@K4JA's station is correct
Automatic Drive Level, known as ALC for short, was originally designed to
limit grid current, preventing overdrive by applying a negative DC
voltage "back" to the exciter/transmitter, especially useful in tetrode
amp situations.
Today, our amps require a drive level between 50-80 W for legal limit.
You can use ALC or not.
Circuits can be internal or external; they can be set by the op, or
automatic.
If external ALC isn't used, the output of the exciter/transmitter should
be reduced using the power output control to avoid over-driving the grids
of the amp. Some ALC circuits (like the Emtron amp) produce a negative
1-10Volts, proportional to the grid current, when overdriving the
tube(s). It's not as easy to over-drive, say, a pair of 3-500Zs w/a
typical 100W rig....
And today, not all transceivers (which have generally replaced
exciters/transmitters) have a direct ALC jack or output jack. Recent
KENWOOD rigs, for instance, have the ALC on a DIN-plug (the REMOTE jack),
while the FT-1000 has one.
N1EU once had a good write up on ALC circuits on his web-site (along
w/lots of other useful information on contesting/DXing/modern rigs). I'm
sure a quick Google search would turn up that link.
I gave up using ALC when I began using triodes in grounded grid. Never
had a rig capable of over-drive.
GL & vy 73 de Don K4ZA
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