On Wed, 8 Nov 2006, JB wrote:

Has anyone done a mod to make a linear amp out of a johnson 6n2 Sounds
like a nice project



I'm presuming you are talking about the 6N2 100 watt xtal controlled
transmitter (and not the Johnson 6N2 Thunderbolt VHF KW amp) originally
meant as an outboard unit for the Ranger (to get DC and modulation power)
to get on 6 or 2, AM/CW.

IIRC, that rig has a 40 watt plate disipation 5894 dual tetrode in the
final (push pull, with neutralization).

For linear operation, the only mods you would need would include DC bias
for the control grid, and fairly well regulated screen grid voltage
(necessitating some disconnection of, IIRC, a clamp tube that protects the
5894 against loss of drive-generated control grid bias).

You would have to look at a schematic to identify anything else that would
need changing. The rig has an oscillator-multiplier string with tuned
circuits for frequencies far from the 6 and 2 meter bands, so you would
need to feed excitation into the 5894 at the push-pull input RF
transformer rather than somewhere else.