[Amps] Modern AM Transmitters and metering

[chris at chrishays.com]

Just to make sure there is no confusion, a properly operating AM transmitter
will double voltage and current (peak) at its output at 100% modulation
regardless of the technology used to make the AM.

Thus current and voltage and, therefore, power must swing up with
modulation.

Meters holding steady at carrier level have modulation cancellation
circuitry that makes the meter easier to read.  The FCC mandates carrier
power, so this is done to make it easy to read the carrier power.

The first I saw of this was a Delta toroidal sampled base current meter. I
believe this has been around since the 70's. I believe Delta holds a patent
on the circuit.

I suspect you will find most front panel "meters" on modern transmitters are
fed via the microprocessor which can interpret the incoming data from the
output sample any way it likes!

Chris AB6QK (retired broadcast engineer dude)