On Jan 11, 12:11*am, Kenneth Scharf wrote:
Scott Dorsey wrote:
Antonio Vernucci wrote:
The only thing you won't be able to do is to measure the plate input power of
the transmitter, which for your application isn't a requirement.
My only concern is that tuning for the minimum cathode current may not be as
sharp as tuning for the minimum plate current, because when plate current
decreases the screen current increases (though only about 1/10 in magnitude).

Is there any way that the tube can fail in such a way that the cathode current
is good but the plate current is not? *Screen damage?
--scott

Another idea would be to connect an rf voltmeter to the antenna
connection and just tune for max rf voltage. *This is the best way to
tune a screen grid power tube anyway. *Most ham rigs have a meter
position to tune for max power output, and this usually is just a diode
connected through a small capacitor to the antenna output of the rig.
The diode is connected through a resistor to the meter, and the meter is
bypassed by another capacitor. *Sometimes a resistive voltage divider is
connected between the diode and the coupling capacitor to the antenna
terminal (for high power rigs). *Should be some circuit ideas in older
ARRL HB's.



Just get a clip on ammeter or hall effect sensor and mesure the
plate direct ?

G ..