The AM Forum

I picked up an old BTI 3-1000 amp recently and just like others I have seen/owned the band switch shows the telltale signs of parasitic arcing. I have info and a kit I purchased from Richard Measures about 10 years ago and will give the amp the full anti-parasite treatment along with the switch repair. Has anyone else had experience with these amps or the 3-1000? I mainly got the amp because I wanted to convert it to use a 4-1000A but thought I might as well try out the 3X tube for awhile.
Skip

Hi Skip.......... good to finally meet ya.

Mom used castor oil for parasites.
Come to think of it, she used it just about anything  ???

I found an odd one while helping a friend get a linear going that is easy to deal with. The input fil choke has a resonance that would make the amp take off. We cured it with a 1 K resistor between the tube side of the choke and ac coupled to ground. This with the right network on the plate of the tube made it rock stable. A 4-1000A will drop right in but the gain will be slightly lower. The tetrode is slightly taller. gfz

That is good info about the filament choke. The slightly lower gain of the 4X1 might also be a + in this situation. The BTI manual mentions that you only need to saw 4 fins off the plate cap to use the taller 4X1. What they don't mention is the fact that the tuned input will need a few mods. The amp was built in the late 60's when exciters had tube finals and Pi networks that weren't fussy about 50 or 100 ohms, so I guess I can excuse the oversight.