on 2/14/02 6:18 AM, R_Davis at WD8JJA@arrl.net wrote:
> Then why do some amplifiers' manuals tell you to monitor the grid current
> and give you a meter function for that purpose?
Well, for one, in the case of a mistuned amp (like when you start tuning the
amp), you may have high grid current. Grid current that is too high can
destroy the tube. Also, if you are matching the amplifier directly into a
reactive load, you will likely get higher grid current than you would into a
50 Ohm load. So you need to watch that too. Some tubes are easily
destroyed by only a small amount of grid current. Others are more robust.
It's really more of a way to just get more data on the functionality of your
amplifier.
As far as tuning goes, Rich is pretty much correct that you tune for peak
output power. I also tune for my plate current dip (and by definition Plate
current minimum = Maximum output power). I never look at grid current when
tuning.
73,
Jon
NA9D
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