1950 Dumont RA-109 Tuning Issue

[Kevin Kuehn]

Originally Posted by Yamamaya42

Also possible but less likely, it could be a alignment issue.
For example on my FADA 895 (RCA 630ts clone), I get no snow when there is nothing hooked to the RF input, just a raster, but I can tune in things on all channels if I try, not very well mind you, but it works, when the video is at peak clarity, the audio is a bit fuzzy, and vice versa, I can find a decent happy medium when video source is DVD or laser disc, ( channel 3), but it's BUZZ-O-MATIC with most most input from the cable box, which is typical for cable input,

Could be. But keep in mind the early RCA clones like your Fada have no automatic gain control(AGC). They had the so called contrast control that actually manually controls the gain of the front end and first few video IF's. That's why you don't automatically get high contrast snow when there's no signal being feed to the tuner, because the gain doesn't increase. If I'm not mistaken your TV has split sound, so you may be able to tweak the sound alignment over to match best picture, provided the picture looks acceptable at some point within the fine tuning range. The fact that the picture and sound are split before the video IF is also what makes the sound alignment so critical. You probably wouldn't need to adjust the sound much to get it to match best picture. The OP's DuMont on the other hand has AGC and a modern contrast control which controls the gain of the first video amplifier.