Micheal, There were two mods to the Twoer and Sixer that I clearly
recall. One was a balanced bridge squelch circuit utilizing some pilot
lamps the other was an MCW mod, similar to the one for the Gonset
Communicator. An RC feedback circuit is created that generates an audio
tone. I'd have to look at some QSTs from 1962 (That's when I built
mine) to see what's up after all these years.

Regarding operation, from Dover AFB, I could talk on 6 meters with
stations in the mid-Atlantic during good propagation. 2 meters was a
close range deal and I don't recall ever doing any real "DX" on that
band with the Twoer. Back in the DC area, I could talk with the locals,
of course.