I've made some progress in aligning the Stromberg-Carlson 400H after a few days of trial and error with a signal generator. The "double hump" was gone after my first adjustment of the IF transformers. I followed the sequence in the alignment instructions, adjusting to get the maximum noise with the signal generator at 455 KHz. But when I turned the signal generator off, it didn't seem to affect the output at all. So, I don't know if I'm using the instrument properly or even if the instrument is working at all. I also did the wave trap adjustment.
There's a great deal of crackling noise when I turn the tuner knob, and when I have a station tuned in, the sound may go totally off (or come back on again) when I touch to tuner knob or the tuner itself. BUT...this only happens below 900 KHz.
I started looking for a bad connection, and I noticed that some of the tuner plates were actually touching when they were engaged, and I verified that with a meter.
https://lh4.googleusercontent.com/-r...%252520144.jpg
So the first thing I want to do is get the plates properly aligned. Does anyone have suggestions on doing this?
I may not need to do anything else after I straighten the plates, but I need to understand more about this signal generator. The instructions are a scant 7 lines, and they're written in Sino-English.
https://lh6.googleusercontent.com/-Z...%252520140.jpg
I understand how to set the frequency for RF output. There are three screwdriver adjustments--modulation level, RF level, and mod. frequency--which are preset at or near their max. Number 9 on the generator is actually labeled mod. in/audio out. I have no idea what the "mod. mode [internal/external]" button is for.
Alignment procedures:
https://lh5.googleusercontent.com/-q...%252520136.jpg
Alignment chart & specs:
https://lh3.googleusercontent.com/-n...%252520130.jpg
Schematic:
https://lh5.googleusercontent.com/-E...%252520100.jpg
Your advice is greatly appreciated.
-Winky