[rfeenstra]

Been working on the 350D HH Scott FM tuner that's the mate to the LK-72-B.  I was having a dickens of a time getting the thing aligned.  Couldn't get the multiplex unit to work worth a crap.  Mono was good.  Finally borrowed the right equipment to get the ratio detector set right.  Still problems with the multiplexer unit.  Had beautiful 19KHz signal and I thought a good 38KHz signal.  I could line the phase up perfectly.  Still, stereo was very touchy. Then I accidentally shorted the grid of the 12AX7 38Khz osc. to the plate with a clip lead. Ouch!  Smelled it. It took out the tube and 2 germanium diodes in the stereo switching circuit.  A blessing in disguise.  Replaced the tube with a NOS RCA I had kicking around (the old Telefunken 12AX7 had tested very strong on my Heathkit TT1), replace the 2 diodes.  Powered it up and viola, everything was great.  The 38KHz signal was much stronger, the decoder started working great, and I could set the R and L separation controls  for excellent separation.  It even works very good with a 5% 19KHz modulation instead of the 10% modulation.  Right and left output look great on the scope.  Best part is it sounds great!  I've been fussin with this thing for the last month and was frustrated.  Success at last.  Lesson: don't trust tube testers.  Use substitution if you can.