Quote:
Originally Posted by DaveWM
Question for Pentode, did you check the cathode current before and after the switch from 82k to 100k?
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I ended up selecting 110k. This yielded -40 volts on the Horizontal Output grid as per the schematic. The cathode current measured 210mA.
Quote:
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I did check the current (200ma) but the RCA schematic did not specify what it should be, just gave the cathode voltage. I suspect 200ma was about right but would like it to be a low as possible. I did adj the eff coil for the dip.
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With 7.5 volts on the cathode, and the cathode resistance to ground at 23.5 ohms (the 82ohm in parallel with the static convergence 100ohm pots), this equals 320mA.
I now measure 5.0 volts for the 210mA. I increased the drive well below the appearance of the drive line. The HO tube runs a bit cooler and I have better regulated HV.