[CQ-Contest] 400W Linears

[Scott Ellington]

At 2:44 PM +0000 3/14/02, andrew (GI0NWG) wrote:

>
>Even a TL922 gets quite warm running an RTTY contest at 400W (the power
>supply gets warm).


Actually, running a 1.5 KW amplifier at 400 W will generate lots of 
heat, unless the amplifier can be loaded very lightly, a tricky thing 
on SSB, and probably impossible on 80 and 160.  If you load a 1.5 KW 
amplifier normally, then reduce the drive to 400 W output, the tubes 
dissipate about as much power as at full output, though the power 
supply does not.  Running a TL922 in the low voltage position helps, 
but it still won't be efficient at normal loading.  To efficiently 
run a 1.5 KW amplifier at 400 W with the normal loading capacitance 
and drive power, the plate voltage would have to be reduced to about 
half the normal value.

73,

Scott  K9MA

-- 
Scott Ellington
Madison, Wisconsin  USA
sdelling at facstaff.wisc.edu