Predicta 17" HV question

[Phil Nelson]

According to my scope manual, that vertical setting is 5 volts per square, so 6 squares in the previous photo would equal 30 volts, but I don't use a scope to measure voltage, so don't count on me having it set up correctly for that.

I turned down the Height control to reduce the pin 3 grid voltage to around -20V as given in the manuals and connected my DMM as well as the scope. This photo shows the voltage reading and waveform at pin 3 (compare to waveform W8 in the Sams manual):



Without changing the Height control or scope settings, I switched the probes to the pin 6 plate (compare to waveform W7 in Sams):



Pin 3 voltage is about -21V (Sams says -20V) and Pin 6 voltage is about 131V (Sams says 115V). The Philco manual calls for 130V on pin 6, so the measured 131V is good enough for me.

Executive summary: on that plate and grid, the waveforms match the models and the voltages look OK, but the height is still badly deficient -- about 2 inches high. Great picture, otherwise.

Phil Nelson