On 1/24/06 12:57 PM, in article 6xwBf.11951$bF.2404@dukeread07, "Uncle
Peter" wrote:


"Straydog" wrote in message
My understanding of AM transmitter technology would estimate that a 32v3,
with ~120 DC input (two 6146s, or were they still using one 4D32?) would
have at most (class C, plate modulated) 70% X 120 = 80 watts of CW carrier
output. 60 watts of audio on that final tube (as a non-linear high level
mixer) will at best, double the _instantaneous_ (peak) input voltage,
therefore power to 240 watts (plate current will _not_ double even if the
plate voltage doubles on peak audio cycle [look at your tube curves again
of iP vs vP at constant biases]) which you could only attempt to measure
with an oscilloscope. Peak output? Could it be more than 240 x 0.7 = 168
watts? I doubt it (unless he's got something like "super-modulation" in
the rig).


Without delving into the limitations of the 32V3, according to the info
from an ARRL publication:

"..since the amplitude at the peak of the upswing is twice the unmodulated
amplitude, the power at this instant is four times the unmodulated, or 400
watts."

Average power, on the other hand, will be 1.5 times carrier. A Class C
amplifier with high level modulation should produce an instaneous PEP
of 4x carrier power.

Pete






Getting back to basics: A 120W (input) power, class C stage, will require
60W of audio (using a high-level, e.g. plate, modulator) for 100%
modulation. If we assume 85% efficiency, then the output will consist of a
Carrier of 102W and two sidebands of 25.5W each.

In my opinion, any other explanation is useless. Do remember that the
carrier amplitude does NOT vary with modulation.

Don