Re: Repairing my Tektronix 454 oscilloscope need some advice
Victor,toggle quoted messageShow quoted text
Today I did more waveform measurements. I always viewed the primary voltage and primary current ( A6302 current probe) waveform and each time I tuned for resonance. Last time I made a frequency reading mistake (when you turn the FG504 knob cw the the frequency deceases...). Without other probes attached it was 27 MHz. Probes at the secondary side lower the resonance frequency somewhat.
From the visible transformer right side 3 very short blank wires go to ceramic supports. From front to rear these are connected to winding terminals 7 (tripler circuit), 9 (cathode, D1452) and 10 (grid, D1440 visible). Resistances to GND: 547R, 243R and about 20k respectively.
Always nice resonance with simultaneously primary voltage maximal, current minimal and no phase shift between these two. In hindsight this could be expected when the primary side acts as a nice parallel RCL circuit with not too low Q factor. R was about 10 Ohm. Also each time the secondary voltage was in phase with the primary.
Amplifications, crude values:
from primary to 7: 375, to 9: 185, to 10: 195.
I did a more precise simultaneous measurement of negative peak at 9 and the DC voltage at HV TP (with DMM). The "loss" was about 10 V (of value about 80 V), looks realistically.
Anyway, it could be very informative to view those secondary waveforms.
On Wed, Feb 19, 2020 at 09:36 PM, Albert Otten wrote: