[AMRadio] keying B+

[Geoff/W5OMR]

How do other people go about keying B+ in their rigs?

What I do, as it was setup in my rig, back in 1986,
is that on the rear apron of the RF deck, is a tap for
bias voltage.  When sufficient drive is applied, the 
current from there to ground closes a contactor 
relay that closes at about the same grid current
required by the 250TH's (45mA per, for a pair
for a total of 90mA - and I run around 125mA
to make sure the tubes are plenty cut-off for Class
C) and when drive is applied, the relay closes
and primary voltage (adjusted by a variac) is 
applied to the plate transformers.

What's another way?  a relay to make/break the 
center-tap to ground connection in the primary
of the plate transformers?

73 = Best Regards,
-Geoff/W5OMR