HP9836C colour alignment (grey scale tracking)

[Gordon JC Pearce MM3YEQ]

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