22-12-2017, 01:28 PM
I must admit to tampering with values in the HMV901 frame oscillator.
I checked all the resistor and capacitor values and the oscillator transformer resistances. They were all correct except for the anode load resistor of the frame oscillator. The schematic shows this as 3M but mine had 3.8M so I changed it to 3M but the outcome was worse 240 line linearity than I got with 3.8M. I also tried 4M but 3.8M seems to be the sweet spot. I did wonder about messing with the line oscillator to improve its linearity but haven't done it.
Peter
I checked all the resistor and capacitor values and the oscillator transformer resistances. They were all correct except for the anode load resistor of the frame oscillator. The schematic shows this as 3M but mine had 3.8M so I changed it to 3M but the outcome was worse 240 line linearity than I got with 3.8M. I also tried 4M but 3.8M seems to be the sweet spot. I did wonder about messing with the line oscillator to improve its linearity but haven't done it.
Peter
