[Amps] The GU84B and GU78B tubes / some brief history
Ian White GM3SEK
gm3sek at ifwtech.co.uk
Tue Oct 30 13:24:32 EDT 2012
Vic K2VCO wrote:
>I'm thinking about this issue now for my project 4CX1000A amplifier.
>The problem I see is the first element getting chopped by the screen
>relay pull-in time, which would have to be under 8 ms. to work. I am
>going to use a fast bias switching arrangement along with the QSK RF
>relays as usual, but it would be nice to also switch the screen voltage.
>Presently, I'm planning to have an "amp enable" switch which will turn
>on the screen voltage and connect the transceiver key out to the QSK
>relays. So the amp won't necessarily be 'armed' whenever it is warmed
>up and ready.
>I have an extra vacuum relay that I could use for this, but Ian's board
>seems to be designed for a 12v relay in this spot!
If you already have a +24V rail available, it will be easy enough to
interlock the vacuum relay switching with the 12_HV rail on the board.
Looks like three logic-level MOSFETs will do it... I'll PM you a small
schematic later.
--
73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek
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