[Amps] 3CX1500A7/8877 vs el cheapo GS-35B

[Bill, W6WRT]

ORIGINAL MESSAGE: 
On Tue, 31 Jul 2012 17:59:09 +0930, Leigh wrote:

>But my point here was that if you design the tank circuit for a higher plate
>voltage and plate load impedance then you won't have to take a hit on the
>efficiency. 
>
>As Jim reported in his reply to my post, he obtained 61% efficiency from a
>pair of GS-35B tubes in GG on 6m with 4100 Volts plate potential under load
>and a tuned Pi-input network of proper Q factor. This result is consistent
>with what other folk achieve from amps using this very cheap tube. 

REPLY: 
Achieving 61% efficiency is good enough, but at 4.1 kVDC you will be exceeding
the manufacturer's ratings. The data sheet says absolute maximum instantaneous
peak anode voltage is 6 kV and you'll be hitting 8.2 kV on peaks and more if
accidentally mis-tuned. Apparently the tube can stand it, but I always hesitate
to exceed ratings. 

73, Bill W6WRT