This is a LA-1000 sweep tube amp, made back in the 80's by Amp Supply Company. Amp Supply was a "spin-off" from Dentron, Amplifiers, and this is an upgraded model of their GLA-1000. This one was in need of work...bad caps, bad tubes, problems with the tuned input, T/R relay problems, etc. She's back up and running strong now, upfitted with Russian 6P45C tubes, new sockets and components. It'll run around 700-800 watts out, depending on band and mode. Here's some pics and a description of the work...
The first steps were to get this beast pulled apart in a way that it could be easily reassembled. Below are the tuned input board, plate choke, and main power supply boards.
Next, the rf board has to be pulled, and tube sockets replaced. The original used 6LQ6 tubes, and didn't use pin 9. The new 6P45C tubes are larger, and require the use of pin 9. The tube pins are also larger in dia, so a different version of the socket must be installed.
The filter caps were toast, and blown due to failed bleeder resistors. This allowed the resting voltage to rise to a value above the rating of the caps, and that stopped the parade :-) Caps were replaced, new sockets modified and installed, and the bottom of the rf board remapped to that needed for the proper pinout of the new tubes.
The above 2 pics are the tuned input board, and below is the RF board, ready to reinstall in the amp with new bleeders, caps, sockets, etc.
The photos below show some mechanical issues to overcome. The tubes are larger in diameter, and taller. Various bits around the inside had to be moved to allow clearance from the tubes so as to not be touching the ends of screws, etc.
Once everything was all reinstalled and tested, I had to cut an opening in the lid and fold a perforated riser, paint it, and install it in the lid. This provided additional clearance for the top of the taller tubes.
Here she is, back on the air and ready for many more years of operation!
Dave WB4IUY
