I received this comment on YT that I think explains why I'm receiving the output of my converter box at two points. I do not have this issue when tuning the commercial LPTV channel 6 broadcast.
That leaves a couple issues. The audio tuning in at two point very close together (one just at the edge of good video and one with bad video) and the odd eye tube indicator. Same issue when tuning in FM radio.
I've aligned the audio several times and it looks perfect to me. I'm going to go through and test the few mica caps in the audio IF and maybe go through the alignment one more time.
Quote:
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That buzz and poor reception of your converter box when you tune low is when you are tuning the lower sideband of the signal. An analog signal is fed into the video modulator with the video signal at baseband and the audio signal at 4.5 MHz. What comes out is an AM signal, with consumer equipment this is sent straight to the set. With Broadcast or cable equipment all by 0.75 MHz of the lower sideband is filtered out. With digital the signal is fed into an 8 Level modulator and again all but 0.75 MHz of the lower sideband is filtered out. This is called vestigial sideband. VSB as it is known is used to allow some redundant information (to make receiver filtering easier) and the use of the carrier (to eliminate the need for a touchy BFO or product detector) to receive what is almost a single sideband signal. If brodcasting used true AM the signal would be 10 MHz wide with VSB the signal is 5.75 MHz with a .25 MHz guard band prior to the lower sideband.
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