Before I run off to invent a new square wheel, here is a question for the
group:
I want to tune up a new cathode input circuit for a 222 MHz amplifier using
a GS23B tetrode (I have some already). I am wondering if for tuning and
test purposes, could the cathode input impedance be simulated by removing the
grid bias and all other voltages except filament and driving the input
with low power rf.
It seems that 50 ohms, for an example, could be simulated with say 10 mW
(+10 dBm) and tweaking the circuit for a grid current of 14 mA at resonance.
The thinking is that at 50 ohms, there will be .707 volts rms with 10 mW of
power and the current would be 14.4 mA due to this
power/voltage/resistance value. The tube can handle 25mA CCS so 14.4 mA is no
strain.
Why do this? Because of the difficulty of connecting a substitute
termination resistor with the needed very short leads at this frequency and it
would be so easy to do.
Any comments and criticism will be cheerfully accepted. I don't mind
octagonal wheels so much, just don't want square ones!
73,
Gerald K5GW
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