I've been reading about contrast buzz lately. It plagues two of my sets, my Motorola 21BT130BE-1 and my Majestic 70, and I predict my Bendix C172U will suffer from it too once restored. Has anybody developed a fix for this? According to an older Antique Radio Forums post: (
http://www.antiqueradios.com/forums/...ic.php?t=64442)
Modern televisions (relatively speaking) use SAW filters in their IF stages to eliminate this issue. I haven't really found any information of what exactly they do/how they work (or any schematics other than block diagrams). Would it be possible to build and/or add one to a vintage set?
the post also mentions in that this issue mainly stems from modern RF modulators not exactly conforming to the 12.5% minimum rule. would there be any way to possibly add some sort of regulator to the modulator output to fix it there?