[Collins] 32S-1 PLATE CURRENT

[Dr. Gerald N. Johnson, electrical engineer]

The neutralization circuit being all reactive, there's nothing there
that should change with time. There are parts that may be temperature
sensitive and that may heat from RF current and change value, but those
should return when cooled. When the neutralization changes, then either
the tubes or those potentially temperature sensitive parts are changing
and probably should be replaced.

There were makes of 6146W that I encountered in the late 60s that would
not work at RF. Made by the Electronic Tube Company, they had the
envelope of a 6146, but totally different internal parts, especially
lacking the shielding inherent in normal 6146x. Those 6146 were what the
US government carried in stock, but when I retubed an S-line for a MARS
station, I bought RCAs because those others would not function at RF.

Since the RF tank components in the S-line (and KWM2) are compact I
propose that one should NOT run 6146B at greater power output than 6146.
Getting a greater power output requires loading heavier, which upsets
the tank circuit design and can easily lead to damage to the loading
padding capacitors (the shaft variable capacitors and plate coil can
probably take the heat) from the increased circulating current. The only
benefit of the 6146B in that situation when properly neutralized is
longevity from operating below its maximum ratings. The difference in dB
is very small though it looks large on a wattmeter.

73, Jerry, K0CQ, Technical Advisor to the CRA.
-- 
Entire content copyright Dr. Gerald N. Johnson, electrical engineer.
Reproduction by permission only.