[Amps] SB-220 bias question

[Bill, W6WRT]

ORIGINAL MESSAGE:

On Mon, 31 Aug 2009 23:41:03 -0400, jeff millar <jeff at wa1hco.net> wrote:

>
>If you really want to chew on something, think about tuning to 1500 CW 
>with sagged plate voltage and hit the amplifier with the first voice 
>peak when the plate supply is still fully charged...probably goes to 
>more than 1500W...and it's not properly tuned for that condition.

REPLY:

Technically you are correct, but it will be mis-tuned in the "good" direction.
It is better for that first voice peak to hit the tube when the VDC is a bit
high than the other way around. If the VDC were low, splatter might occur
because the tube could "flat-top" at the lower plate voltage. Having the VDC a
few hundred volts higher gives a bit more headroom.

Of course, the best approach with SSB  is to tune up at full peak power and then
reduce the drive about 5%. If everyone would do that, splatter would be a thing
of the past. 

73, Bill W6WRT