[Amps] SB-220 bias question

[Bill, W6WRT]

On Sat, 29 Aug 2009 21:30:02 -0400, "Joe Subich, W4TV" <lists at subich.com> wrote:

>
>No, I'm saying they are all designed to operate at 1500 Watts 
>output.  If one reduces power without reducing the plate voltage 
>appropriately, the plate load impedance will change.  Unless the 
>"L" in the pi-network is changed to the correct value for the new 
>plate load impedance, the pi network will be very different than 
>what was designed for normal operation. 

That part is correct, however only the efficiency suffers. No harm is done..
>
>If the components (particularly the pi-network coil and band 
>switch) are not sized appropriately for the higher currents 
>and voltages, they will fail prematurely. 

That part is incorrect. The voltages and currents do not increase when power is
reduced. They decrease.

73, Bill W6WRT