Hi Mark, I don't have the Sams information on this set but I have the equivalent Riders. I'll email it to you, it might complement the Sams. I think you're talking about the "S" shaped discriminator alignment, that's fig. 5 in the Rider info. The signal is sent as a carrier that doesn't vary in strength but varies in frequency around the steady carrier frequency with the modulation (AF) signal. In this (most) sets the incoming requency is converted to 10.7 MHz IF for amplification and demodulation to recover the audio. The IF amplifiers are aligned to pass signals around 10.7 MHz and a hundred kHz either side. In the demodulator the tuned circuits and detector diodes are arranged to produce zero volts output with a 10.7 MHz signal and a positive output at lower frequencies, negative output at higher frequencies, as per the "S" curve. So as the frequency is modulated up and down a linear output signal is produced. In order for this to occur without distortion the curve has to be smooth and symetrical and centred around 10.7 MHz. That's why it's specified to be zero at this operating (10.7) frequency. It's usual to use a sweep frequency generator to adjust the curves and I hope from your posting you have one of these. Hope this helps, Don Black.
: I recently attempted (with great assistance) to align the FM on my Stewart-Warner 9151-A.
: I followed the FM alignment instructions in the Sams Photofact under the heading "FM IF Alignment
: Using FM Signal Generator and Oscilloscope." Procedure step 5 could not be simulated using modern day
: equipment. This step requires placing 10.7 MHz at the center of the crossover lines by adjusting one of the
: FM IF transformers (A12). If anyone has a copy of the Sam's Photofact, could you e-mail and explain what
: Figure 2 represents? It looks like two sine waves 180 degrees out of phase. This is my first attempt at FM alignment.
: Thanks!