Quote:
Originally Posted by tubesrule
The problem I've run into with slope detection, while it does work it requires the audio carrier to be centered right on the slope, meaning any slight drift in the LO and the audio moves off the slope and drops out. The RCA LO design seems to be a bit more stable than the GE, but they require constant touching up of the fine tuning the entire time you run them. The other problem is modern modulators set the audio carrier -16dB from the video whereas it was originally set to -6dB.
I've given up on slope detection since my converters are capable of AM and FM audio modulation and variable carrier level. Driving these sets with a -6dB AM signal is night and day from using slope detection. As a bonus I program the converter for 441 line and the original carrier frequencies not that this is required.
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Almost five years after the fact I guess I'm still not used to the obsolescence of NTSC and the reality that
all analog sets require some kind of converter now. And yet I did deliberately use past tense because I wasn't certain that the museum was still running the prewar sets with an ordinary modulator rather than one of your converters.