Rich writes:
> > Rich, where is K-202?
> On the 374 Plug In Board CB2 Schematic, to the right of Q203, D213
> and Q204. K202 is labeled "Grid" so I assume it has something to do
> with protecting the grid.
If you would follow the schematic ... (or read the manual at page 5e)
you will find it disables the PTT line if grid current is excessive.
How odd ... Alpha does the same thing as G3SEK, WD7S, and any number
of other builders ... they ground the grid solidly, use an effective
and resettable grid current trip, an anode overcurrent trip and a
properly sized "glitch" resistor. Seems to me that's the norm for
commercial transmitters, induction heating and MRI amplifiers too.
None of them use a fuse between the grid and ground.
> > Now, what amplifier is it that uses a transistor to open a 50 A
> > grid circuit?
>
> There aren't any, which was my point.
Then why were you saying there was one?
73,
... Joe, W4TV
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