05-01-2018, 12:18 AM
voltages are well within operating limitations of the tube. The amp sounds great this way and I don't really push it that hard so I don't run into a power problem because of the lower idle current, so I'll leave it this way. It runs fairly cool. No fan yet, but it's fully exposed so cooling is good. I have looked seriously at the bias setup that many are adding to the Fisher amps. The active control of the bias and screen voltage as a function of the B+ apparently greatly reduces the idle current while maintaining the power and distortion characteristics of a properly biased output. Looks interesting. The AudioKarma forum has a good bit of info that Dave Gillespie has put out on the fishers that should also work on the Scott. It's working so good right now that I'll probably just leave it alone for now.
I've got the matching FM tuner up and running now - A HH Scott Stereomaster 350D. I have the RF and IF sections aligned using a spectrum analyzer, sweep generator, scope. I don't have a multiplex generator so getting the multiplex section aligned and adjusted properly is a bit of a problem. I can't find any Scott info on this unit outside of the schematic. No procedures, so I have to adapt from other equipment without the proper test equipment. It works and I stereo is ok, but i think proper adjustment would improve separation. I seem to have trouble getting the 19khz pilot to peak at the same place as the signal. I need to be just off peak signal for the stereo to lock in. I don't know enough about this stuff to know what to do to fix it. I also am not sure how to adjust the R and L separation controls for best separation. I've learned a lot, though, in working with this thing!
I've got the matching FM tuner up and running now - A HH Scott Stereomaster 350D. I have the RF and IF sections aligned using a spectrum analyzer, sweep generator, scope. I don't have a multiplex generator so getting the multiplex section aligned and adjusted properly is a bit of a problem. I can't find any Scott info on this unit outside of the schematic. No procedures, so I have to adapt from other equipment without the proper test equipment. It works and I stereo is ok, but i think proper adjustment would improve separation. I seem to have trouble getting the 19khz pilot to peak at the same place as the signal. I need to be just off peak signal for the stereo to lock in. I don't know enough about this stuff to know what to do to fix it. I also am not sure how to adjust the R and L separation controls for best separation. I've learned a lot, though, in working with this thing!