[MrFixr55]

Hi TV Man,

I have a 400 and an 800. I found them on the street within 2 years of each other about 30 years ago. Both work, but I do need to get through them. One strange thing that occurs to the 7868 output tubes is that they crack at the base. I had one bad one so I went to an old Bogen PA amp that I have that has 4 of them. 2 were cracked also, and, of course, all cracked tubes lost vacuum.

Someday, I will sell the 400. The 800 is a keeper because it has both AM and FM (from when they first experimented with stereo by sending one channel on AM, the other on FM), and FM MPX Stereo.

I haven't played either of them for a while, but the last time I did, neither had SMD.

Good luck with yours. I would definitely consider getting rid of the selenium rectifier, as I believe that it also powers the preamp 12AX7 filaments in addition to providing the C- for the output stage. I would also consider "fusing" the output tubes by putting 10 ohm 1/4 watt resistors between the output tube cathodes and chassis ground instead of the cathodes directly connected to ground. This may save the tubes or OPTs if you lose C-.