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Let me expand on my explanation: when the color was correct, the RF fine tuning was tuned, as best I can tell, so that the color carrier was tuned
in the IF strip where the audio carrier is supposed to be! The audio was well
down in frequency (in the IF of course, as the RF signal is lower in frequency
than the RF oscillator) to where the IF response was nil, so no audio bars.
This meant that the main video carrier (in the IF) was well down in frequency into what should be the flat part of the IF response: 6dB higher in amplitude than its "proper" spot half way up (in amplitude) on the IF response.
All this implies to me that something awful is wrong with the RF/IF response curves. The fact that the problem varies with channel when connected to my modulator with short cables (two, as there was a step attenuator there) implies its in the receiver. Ch. 3 was particularly bad. I checked that it was not the external balun by using a resistive brigded-T pad in place of it.
Last edited by dtvmcdonald; 05-10-2022 at 05:56 PM.
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