[Amps] trying to understand 1296 cavity amp

[jmltinc at aol.com]

Different, isn't it? There is no physical connection between the plate and the cavity.

My Elmer, a microwaver and builder extraordinaire, once called it "Black Magic". Not satisfied with that, I scoured a half of a dozen books for the answer. Found several articles on how to build them, but nothing regarding the "Black Magic" part.

My guess the tube is capacitively coupled to the cavity. Perhaps someone can confirm or debunk that.

If not, I have a friend at Fermilab that can tell me as that is his gig.

-J




-----Original Message-----
From: Gary Patterson <gpatterson53 at hotmail.com>
To: jmltinc at aol.com
Sent: Fri, Nov 20, 2009 5:07 pm
Subject: RE: [Amps] trying to understand 1296 cavity amp


 
 
Thanks John.   My problem is there is no physical connection between the 2c39 plate and the cavity to allow skin effect action to put rf into the cavity.
 
73
 
> To: amps at contesting.com
> Date: Fri, 20 Nov 2009 15:05:27 -0500
> From: jmltinc at aol.com
> Subject: Re: [Amps] trying to understand 1296 cavity amp
> 
> 
> Gary,
> 
> Although the anode connection (fingerstock of the anode by-pass plate) is on the outside of the cavity, the tuned circuit is the inside of the cavity. Due to skin effect, RF cannot not pass through the walls of the cavity (or through the cross section of the fingerstock). 
> 
> As the outside of the cavity is not a tuned circuit; a large, coherent (in-phase) RF signal cannot develop on the anode by-pass plate nor the anode cooler, and both are essentially at DC potential.
> 
> -John, N9RF
> 
> 
> 
> 
> -----Original Message-----
> From: Gary Patterson <gpatterson53 at hotmail.com>
> To: amps at contesting.com
> Sent: Fri, Nov 20, 2009 9:48 am
> Subject: [Amps] trying to understand 1296 cavity amp
> 
> 
> 
> I have a n6ca 2c39 1296 cavity amp and have trouble understanding how it works. 
> he 2c39 plate has a large teflon sheet capacitor to ground. I dont understand 
> ow any rf gets into the cavity when the plate is dead shorted with this 
> apacitor. any help?
> 
> gary
> w4af
> 
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