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Re: [Amps] cathode emission prediction

To: jtml@vla.com
Subject: Re: [Amps] cathode emission prediction
From: Jeff Blaine <keepwalking188@yahoo.com>
Date: Thu, 12 Mar 2009 20:42:22 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Thanks John,

Have a nice week break.

Unfortunately, for guys that are using the Russian triodes, getting an 
proper set of curves like what Eimac users enjoy is but only a dream...

I will dig out the C&F again and look it over.  Had not focused much on 
the cathode consideration prior to your suggestions.  Which I really 
appreciate.

73/jeff/ac0c

John Lyles wrote:
>   
>> For the cathode emission limts, do you think there is a way to 
>> characterize this?  Or perhaps infer it from pulse-mode data assuming 
>> comprable CCW data is not available?
>> 73/jeff/ac0c
>>     
>
> Yes, it is available already measured, on the datasheet. Look at the constant 
> current curves on an Eimac sheet, for instance. The  top curve is pretty much 
> the peak that they tested in some fashion, and it is usually a LOT higher 
> than your DC readings. If you are familiar with Tube calculator #5 by Eimac, 
> you know how you have a particular load line that swings back and forth, 
> usually diagonally intersecting the constant currernt curves. These may be 
> cathode or plate current lines, but they are usually close. The peaks of the 
> RF fundamental sinewave will be swinging up into the high current regions on 
> that part of the cycle and down to near cutoff on the other part. Or into 
> cutoff.  This all depends on the class of operation, AB, B and C for 
> instance. Take a look at Care and Feeding on the curves and using them to 
> predict operating points. 
> I am going off line for a week for R&R.
> 73
> John
> K5PRO
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