Quote:
Originally Posted by FERNSEH
In the Ultra V9-17 only the RF amplifier and common vision and sound IF amplifier are controlled by the vision AGC.
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Hi David,
I noticed in the VT9-17, there is also a connection from the AGC line to the grid of the line o/p valve. Is this some attempt to regulate changes in picture size caused by high beam current on bright scenes?
Last night,I built the VT9-17 circuit as it is shown in the R&TV book. It seems applicable to the Pilot as the various pulse feeds are available with the correct polarity. The frame o/p anode waveform & also the video from the detector are the right way up!
I used the triode section of a 30FL1 and 1N4148's for the diodes just for testing.
Conveniently, the circuit shows expected waveforms throughout the circuit.
Initial tests show that an increase in video signal makes the resulting AGC control voltage more negative as you would expect.
I've not had a chance to do more involved investigation yet to see if the circuit is actually working correctly.
Hopefully, I can have another play tonight!
Cheers
Nick