Quote:
Originally Posted by Hybrid tellies
Looks promising. .
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Hi Simon, it sure is. The line scan coils have been reversed so at least the test card is the right way around. A little probing around the IFs revealed that the final IF amplifier was a bit "peaky". A tweek of the core of the last IF transformer has cleaned up the picture.
The AGC system in this set is a bit primitive. It's a mean level system operating on the first IF amplifier transistor only. An increase of signal strength reduces the negative bias voltage to the PNP OC171 transistor.
A base bias potentiometer controls the gain of the RF amplifier transistor, an AF102
Six years later with the introduction of silicon transistors the forward AGC control system became the norm.
The frame linearity controls will have to be replaced.
DFWB.