[TenTec] Hercules II / 9420 high duty cycle

[Ken Brown]

Hi all,

I used my Hercules II and 9420 power supply in the ARRL DX contest this 
weekend. The amplifier worked great, never showing any signs of strain 
or overheating. The 9420 power supply got quite hot. It is powering only 
the Hercules II. I am using a separate 961 to power the Omni VI exciter. 
The specifications for the Hercules II says: Duty Cycle CW/RTTY - 50% 
duty cycle continuously. The specifications sheet for the 9420 says 
nothing about duty cycle. The power supply seemed to be getting too hot 
to continue, so I gave it a break. I used just my hand to feel the 
temperature, no instruments were used to measure the temperature. My 
9420 sits on the floor with two or three inches of clearance on all 
sides for air flow. I am running it from 240 VAC. Before I use it again 
for high duty cycle operation, I feel that I need to improve the cooling 
of the 9420, probably by adding a fan or two. I am interested to hear 
from anyone who has used the Hercules II and 9420 in a contest or other 
high duty cycle operation. Is my experience with the power supply 
heating typical? Has anyone mounted a fan on a 9420? I am thinking about 
fabricating a new top panel, since it is the simplest part of the 
chassis and has nothing mounted to it, and mounting a fan on it.

Thanks for any sage advice,

Ken N6KB