[Amps] 3CX800 Oscillation

[Ian White GM3SEK]

Hardy Landskov wrote:
>I built a 6 meter amp using this tube and put it in a basket case SB200. The
>result was a very beautiful amp if I do say so myself but it "takes off"
>with more than a little drive. Has anyone out there have any experience with
>oscillating 3CX800's? If so what was the cure?

How are you grounding the grid? If you are using contact fingers onto 
the grid ring (rather than the pins in the base) the 3CX800 should be 
stable up to UHF - unless there is some major external feedback path.

A few quick things to try: Does the oscillation happen with all the 
covers on? Does it happen with a dummy load? Have you tried using 
different cables?


-- 

73 from Ian GM3SEK
http://www.ifwtech.co.uk/g3sek