The total grid dissipation on a properly loaded 8877 amp running at
4000 volts and loaded to 800 ma plate current is 8.2 watts. Whether
the maximum grid dissipation is 20 or 25 watts is not near as important
as limiting the maximum grid current to 70-90 ma at all times. This
will protect the tube from loss of load, selecting the wrong antenna
in the heat of battle, and loading capacitor failure or miss adjustment.
If tune-up procedure is done properly, the grid should never see over
10 watts dissipation. Grid current on a properly loaded 8877 should be
50-65 ma. Under certain conditions, a 100 watt exciter can cause grid
damage to a pair of these tubes. I am sure we all have better things to
spend our money on than increasing Eimac's bottom line!
(((73)))
Phil, K5PC
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