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Re: [Amps] The GU84B and GU78B tubes / some brief history

To: amps@contesting.com
Subject: Re: [Amps] The GU84B and GU78B tubes / some brief history
From: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Reply-to: Ian White GM3SEK <gm3sek@ifwtech.co.uk>
Date: Tue, 30 Oct 2012 17:24:32 +0000
List-post: <amps@contesting.com">mailto:amps@contesting.com>
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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