Philips India radio B6CA37A/01 (Algemeen)

door Pieter Vos , 26.07.2015, 15:41 (3410 dagen geleden) @ ruudtx

To check wether the oscillator operates you may also measure the grid voltage with a high impedance DC voltage meter. Use a series resitor of at least 100 kilo-ohm between the oscillator tube grid and the voltage meter in order to have the capitance of the meter leads isolated from the oscillator circuit. The oscillator tube grid should have substantial negative voltage when the oscillator produces signal. When the oscillator stpos working the grid voltage returns to approximal zero.

In stead of a high impedance DC voltage meter one may also use a magic eye tube which is in fact a qualitative negative voltage indicator.

Best wishes, Pieter.