27 Sep
2008
27 Sep
'08
12:27 a.m.
Tony Duell wrote:
I am wondering about measuring the average beam
current when displaying
the level 15 raster of each primary colour and making sure it's
reasonable. Beam current is near enough the final anode current, so
measuring that would do. But that would mean having a microammeter
floating at 25kV wrt earth. What fun...
I haven't seen the circuit, but I'm guessing you'll find some handy
resistor around the cathode to sample the voltage across. Obviously
this will be somewhat high due to the grid currents, but my gut feeling
is that they won't be significant compared to the anode current.
Gordon