K8CC added:
I've gotten around this by using only old-style glass bottle tubes in my
HF contesting station. In the exact same examples given above, a pair of
3-500Zs, a 4-1000A or a 3-1000Z shows essentially no change in operating
conditions when the loads are switched.
I'm kicking myself for getting rid of my TL-922. I think I may still have
an
L-4B around here somewhere - where did it go?
With the modern amps, Tim/K3LR offered the tip of loading the amp slightly
heavier than normal to accomodate load impedance changes. With most of
the modern tubes, grid current is the killer so loading the amp slightly
on the heavy side (say giving up 50W of power output on top of 1500W)
drops the grid current significantly, and gives you some "wiggle room".
Yes, this helps a bit, though my antennas (a tribander & a SteppIR
dipole) are just too far apart most of the time. Even more fun trying
to keep the amp happy as the tribander can change its appearance
quite a bit should the second radio be using it on one band instead
of another.
I guess it's some consolation that even if I did have the room to do
proper antennas here, that this problem wouldn't entirely go away.
I think I should start collecting bits & put tuners on everything like
I think N5OT does.
73 & HLNY, VR2BrettGraham
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