23-12-2020, 10:37 AM
I'm sure it's the thermistor, its common on most of the Bush sets of the era. Low heater current is as bad for valves as much is over running them. Take for example a rectifier. Low heaters, will result in low HT and increase the dissipation in rectification increasing heat. This is far more noticeable in a TV than a radio. In fact in this set the HT is below the spec, bringing up the heater voltage to its correct level increases HT by 15v. Later last evening I realised the HT drops slowly after the initial warm up. With the correct heater current this gradual sag doesn't happen and the reduction in width is cured.
