[Boatanchors] Small triode drive

[Carl]

----- Original Message ----- 
From: "Barrie Smith" <barrie at centric.net>
To: "Boatanchors Mail List" <boatanchors at mailman.qth.net>
Sent: Thursday, April 09, 2009 9:10 PM
Subject: [Boatanchors] Small triode drive


> Looking at the data sheets for the 35TG and the 25T, I'm puzzled about 
> the driving requirements.
>
> A pair of 25Ts require 4.4 watts drive, at 1500 plate volts, for 150 
> watts out.  (A single 25T requires 2.2 watts drive.  I'm assuming that 
> a push-pull pair would require 4.4 watts)
>
> A single 35T/35TG requires 9 watts drive, at 1500 plate volts, for 141 
> watts out.
>
> Since I'm hoping to drive this rig with a Meissner Signal shifter, I 
> don't think that I can drive one 35TG with that.  I think I could 
> drive a pair of 25Ts with the MSS.
>
> What am I missing here?
>
> 73, Barrie, W7ALW

An 813?

Figuring on 12-15W out of the signal Drifter, and then various losses 
and you will be lucky to have 8-10W at the grids. Just about right for a 
pair of 3C24's at 1500-2000V but an 813 will do twice that.

Or for even older tubes use a pair of 814/VT-154. Even Epay cant get 
over $10 for NIB ones. A real sleeper tube and the predecessor of the 
813. An easy 300W on CW.

Carl
KM1H


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