This is an old Kris monoband amp from back around the late 70's. They were simple grounded grid amps using a pair of 6JU6 sweep tubes. This amp was a dog when I got it...power supply problems, rf sensing problems in the keying circuit, tubes shot, and other issues.I set out to get it running and back on the air.
Before I would repair the other issues, I had to locate a set of tubes. The 6JU6's are almost unobtainium these days, in new condition. I had been looking at a Russian glass tube that is still available as new, and decided this was a good time to test my idea. The Russian tubes are larger, but have the same tube socket (and are fairly inexpensive!)...I rewired the sockets, repaired all of the other issues, and set it up on 10 meters. With a Radio Shack HTX-10 this little amp now does about 150 watts out on SSB, & about 100 watts out on FM.
Below are a few pics, including some to show the difference in the physical size of the tubes...
There was a considerable difference in the physical size of the tubes. They were pretty close to the top cover, but with some work around the parasitic suppressors and plate caps, I was able to fit it all inside.
