Harvey Wells 6N7 Mod

[KA8WTK]

  Just got a TBS50C (No VFO or PS ) that has a 6N7 tube added. This is probably an audio driver of sorts so you can use outboard audio instead of a carbon mic.
  Has anyone seen this mod or know where it came from so I can check what was done against some known documentation? Do you have a copy?

Thanks,
Bill KA8WTK

[KA0HCP]

I haven't seen that in any of my reading or collecting on the TBS-50.

[KA0HCP]

http://www.swedeart.com/harvey/articles/tbs50/cq1955-hw1.jpg

here is a mod from CQ Magazine, 1955, using a 6SN7 preamp.

The tribute website is wonderful and I can spend hours reading it.

[w4bfs]

just went thru looking at a 6N7 added to an AF67 .... with 300 V you can go zero bias pp and get about 10 W out of a 6N7.... the downside is a 500 ohm min grid impedance and abt 200 mW of audio drive ... it isn't enuff audio unless you are running reduced rf pwr .... the 807 / 6l6 makes good power class ab1 so why bother ?

[KA8WTK]

  What it looks like is the 6N7 was added to drive the 6L6s. The audio was brought to the grid of the 6N7. The input transformer was eliminated (removed).