I have now got an AM6155 running on 432MHz using the W3RJW
mods to the RF cavity (need a new blower BTW) but although
I get 300mA of anode current from a few watts of drive, I can
not get more than 100W output. More drive starts to affect the
grid biasing and leads to excessive screen current. This is with
100mA standing bias. I expected 40% efficiency, not 15%.
I have tried all positions of the loading capacitor. The tune dial
reads 151-155 at peak output, depending to some extent on the loading.
Is is possible that the tarnish on the silver plating is to blame
for this or might there be some other reason?
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|