I believe those were peak *input* power levels. This is what
upset AM fans so much when it was changed to 1500 W peak output,
because they could get more than 1500 W peak? power with 2000 W
peak input running Class C plate modulation.
73,
Kim N5OP
On 4/17/2025 5:46 PM, Dave w6de wrote:
Grids
don¡¯t have enough thermal mass for protection like a plate
has.?
Exceeding peak values are enough to blow out a grid.
?
Many
moons ago, I had a Henry 3-KA it had a pair of Eimac 3-500Zs
had sheet metal plates and ~ 3500 Volts on the plates.? It was a beast.?
It was a mess when I bought it.? I had to rebuilt the
plate circuit wiring and replace the noisy plate circuit
fan.?
I replaced the fan with a more powerful Dayton
squirrel cage blower.
This
was in the days when the US FCC power limits were 2K peak
output.?
The FCC intended that 2K peak to be for SSB.
?But the rule was written 2KW peak.?
2KW peak for SSB is also 2 KW peak for CW. ?At that power level the
plates were a nice dull red¡ªjust like the spec sheets says.?
And a Bird Wattmeter indicated 2 KW output¡ªprobably
exceeded the 500 Watt per tube dissipation but the greater
air volume helped mitigate that some.?
Worked out well for a bunch of CQ World-Wide
Contests.
?
73,
Dave,
w6de
?
?
I
can¡¯t help but chime in: RMS is the only value that makes
sense. Outlet voltage in your house is 120 V RMS. There¡¯s no
such thing as ¡°RMS power¡±; peak power come from peak RMS
values.?
N5OP
?
"People
that make music together cannot be enemies, at
least as long as the music lasts."?-- Paul
Hindemith
?
Duty cycle
is considered. These are peak voltage obtained by
100% duty cycle continues wave.
the Eimac
formula for calculating grid dissipation is based
on peak.?
Pg = vga X Ig
anyway,
anything I state is like I said, this is what I
know, how I calculate it. I¡¯m not an engineer,
just an amateur. There are plenty of engineers
floating around here and if I¡¯m incorrect, I would
love to be corrected as that would benefit myself
and I¡¯m always open to learning more. Any day I
can learn is a day of victory.
PS, this
stuff is the fun part of the hobby!?
--
Kim Elmore, Ph.D. (Adj. Assoc. Prof., OU
School of
Meteorology, CCM, PP SEL/MEL/Glider, UAS, N5OP, 2nd Class
Radiotelegraph, GROL)
¡°Listen, it's too big a world to be
in competition with everybody
else. The only guy I have to get better than is who I am
right now.¡± ¨C Col.
Sherman T. Potter, 4077 M.A.S.H.
