I decided to build a similar (but not identical) field strength meter to this one:
https://www.airplanesandrockets.com/ele ... 54-man.htmI have it all together, but can't get the meter to budge. My multimeter is broken and can't measure anything but voltage and shorts.
I have experimentally determined my meter is 0-5 mA. The tube is a subminiature 1J29B, in triode configuration. If I replace the potentiometer with a set of modern Apple earphones, I can hear a signal injected into the grid. No change on the meter. I know every component is working, so... What could the issue be?
All connections are solid. My only modification is to remove the variable capacitor- It shouldn't have anything to do with meter reading.
It seems the issue is the tube isn't outputting enough current, but because I can hear the injected signal, it would seem that current IS flowing. I didn't think these headphones worked under 10 mA, so something is way off.
I'm using 1.5 V across the filaments in series (rated 2 V in series), and 19 V plate voltage.