[AMPS] 3CX800

[Peter_Chadwick@mitel.com (Peter Chadwick)]

Rich says:

>In a typical 4CX1500B Class AB1 amplifier, the grid-bias supply has 
>enough series R to limit grid-diss. to a safe value in the event that the 
>operator fails to adjust the grid bias to a level that allows no grid 
>current with max. drive applied. 

Shouldn't the bias be set for correct zero signal plate current? Then limit
the drive. There's also a maximum for grid circuit resistance.

I was thinking of a 'last resort' ALC output for my 4CX1000 provided when
the grid voltage gets more positive than -5 or -6 volts. I'm not a great
lover of ALC for preventing overload - it's a 'shutting the stable door
after the horse has bolted' approach to my mind - but as a last resort,
followed by a grid current  trip (or maybe a PIN diode attenuator) when the
grid current starts (4CX1000s are rated at zero watts grid dissipation), it
may be useful. Comments?

73

Peter G3RZP




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