[ARC5] SG Keying of ARC-5 TX

[WA5CAB at cs.com]

The Command Set transmitters worked just fine box stock.  If you can build 
a MOSFET DPDT relay that will handle 300 VDC, you can just as easily build 
one rated for 600 VDC and run unbutchered transmitters.

Robert Downs - Houston
wa5cab dot com (Web Store)
MVPA 9480

In a message dated 11/18/2016 20:32:23 PM Central Standard Time, 
tarheel6 at msn.com writes: 
> 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
> 
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