UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

FERNSEH · 30th Apr 2017, 5:42 pm

The line oscillator is tested in the same manner as the frame oscillator. The LTB circuits are isolated from the main receiver and supplied from a separate power supply.
The line blocking oscillator is working OK. Easy to adjust for a 100microsecond repetition rate. Good 50volt p - p sawtooth waveform present at the control grid of the KT44 line output valve.
Before the mains is ever connected to this set what really is needed is a complete set of new HT supply electrolytics.
So now it could be said the timebases are serviceable. Now I'll turn my attention to the 4.5Mc/s sound IF amplifier. get rid of that SP61 valve, fit an international octal base valve as the replacement.

DFWB.

30th Apr 2017, 5:42 pm	#29
FERNSEH Dekatron Join Date: Mar 2005 Location: Gateshead, Tyne and Wear, UK. Posts: 7,444	Re: HMV 1804 Television. The line oscillator is tested in the same manner as the frame oscillator. The LTB circuits are isolated from the main receiver and supplied from a separate power supply. The line blocking oscillator is working OK. Easy to adjust for a 100microsecond repetition rate. Good 50volt p - p sawtooth waveform present at the control grid of the KT44 line output valve. Before the mains is ever connected to this set what really is needed is a complete set of new HT supply electrolytics. So now it could be said the timebases are serviceable. Now I'll turn my attention to the 4.5Mc/s sound IF amplifier. get rid of that SP61 valve, fit an international octal base valve as the replacement. DFWB.