Articles — Tube Testing — 6LW6 Sweep Tube

[giboni]

I will be retiring soon. I can then expand my hobby into audio and guitar amps.

I realize how busy for years the author of this article has been.

Articles — Tube Testing — 6LW6 Sweep Tube

I would like to finish building my RF sweep tube amp. No luck getting it to function correctly. It has to be grid driven.Using 36LW6

Can I get the parts list and schematic for the RF amp mentioned in the 6LW6
sweep tube article ?

 

[Tubelab_com]

I discovered the 6LW6 tube back when I worked in TV repair (1970 or 1971). It was simply the biggest sweep tube that I had ever seen. I went on to work in the solid state world, and mostly forgot about tubes.

I briefly used this tube again when I played with RF amplifiers in the mid 1970's. It was easier to find octal sockets than the compactron sockets for the commonly used 6JE6/6LQ6. The 6LW6 also put out more RF power.

My HF vacuum tube RF amp experiments took place in the mid 1970's, about 45 years ago. Even then I often "designed" things by collecting a pile of suitable parts, a few ideas, and just trying things until it worked, or my patience ran out. There never was a formal schematic or parts list, and if there was, I couldn't find it now 45 years later.

I made several RF amps at the time often starting with a design found in older ARRL handbooks, or even a dead HF amplifier and rebuilding it with parts that I had. I know that I used the 6LW6 and other big TV sweep tubes in HF amps, but I don't remember the details of any specific design. If you can find an old circuit with 6146 tubes, it should be a good place to start.

Most were similar, power, bias, and an RF Pi network match on input and output. It's best to keep the input and output stuff in separate compartments, which usually meant that the input, power and bias went under the chassis and the output stuff went on the top, under a cage. The typical 100 ohm 2 watt resistor with wire wrapped around it mounted at the plate cap is mandatory with TV sweep tubes. So is a good screen bypass right at the socket.

By the 1980's all of my RF stuff was solid state since I worked at Motorola, the in house semiconductor sales guy was a ham radio guy, and I was a transmitter design engineer and a ham.