[Boatanchors] One Tube QSK Box (maybe called the "imp", Handbook, 1964)

[Bill Acito W1PA]

When I was a novice, I had bought a used NC300 and a DX60B with VFO, and
it came with a homebrew, one tube QSK box that provided full QSK.

Can anyone point me to a schematic for this beast, or something like it?

Thanks,

Bill
W1PA