Cathode Current Measurement

[wabr101]

I have a CTC 39, RCAs last tube set...I measured the current flowing through the horizontal output without the capacitor and then read that I need a capacitor across the meter. What does the capacitor do across the meter when measuring current and why is it important?

[old_tv_nut]

The capacitor gives you an accurate reading of average current because some meters may not read the correct average (DC) value of a varying waveform.