[ARC5] SG Keying of ARC-5 TX

[Tom Bridgers]

Recently found out that you could key an ARC-5 by using an appropriate sized SPDT 28 VDC relay that toggles between a cutoff voltage and normal SG voltage.

In transmit mode, after applying B+ and VFO voltage, on key up a large negative voltage (about -200 volts)  is applied to the screen grids.  On key down the relay applies the normal +275 volts to the SG.

This circuit eliminates back wave, and was recommended in GE Ham Tips in the early 1950's. Though not specifically to the ARC-5, but for use generally to transmitters.  This method was implemented successfully by Ron Baggs , which is where I found out about it.

Instead of using a mechanical relay, it would be really cool to figure out how a MOSFET could be used instead to implement this circuit.
Tom KE4RHH