[AMPS] AL1500
Ian White, G3SEK
Ian White, G3SEK" <g3sek@ifwtech.com
Thu, 6 Dec 2001 13:18:07 +0000
Earlier, I wrote:
>So the way it's normally meant to operate is that grid current flows
>down through R3
[...]
>What happens to Q2 in a major surge depends on the other things
>connected to R20. If the circuit is at all conventional, R20 is the
>grid current metering resistor, so there must be a meter connected
>across it, and hopefully also a protection diode (anode to ground).
>Then the B-minus rail and anode current meter connect to the top of R3.
>
>R20 is in the path of any major current surge from B+ to ground, as it
>flows up through R3 to return to B-minus. If the protection diode is
>connected across R3, the voltage drop will not exceed say 0.7-0.8V, so
>both R3 and Q2 should survive OK.
Sorry - "R3" should be R20, everywhere.
--
73 from Ian G3SEK Editor, 'The VHF/UHF DX Book'
'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.com/g3sek
--
FAQ on WWW: http://www.contesting.com/FAQ/amps
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com