Re: Tube Coils (fwd)

To: tesla-at-pupman-dot-com
Subject: Re: Tube Coils (fwd)
From: Tesla List <mod1-at-pupman-dot-com>
Date: Fri, 28 Feb 1997 20:33:53 -0700 (MST)
Approved: mod1-at-poodle.pupman-dot-com

---------- Forwarded message ----------
Date: Fri, 28 Feb 1997 00:19:25 -0500 (EST)
From: richard hull <rhull-at-richmond.infi-dot-net>
To: Tesla List <mod1-at-pupman-dot-com>
Subject: Re: Tube Coils (fwd)

At 09:30 PM 2/26/97 -0700, you wrote:
>
>
>---------- Forwarded message ----------
>Date: Wed, 26 Feb 1997 17:52:51 -0800 (PST)
>From: "Edward V. Phillips" <ed-at-alumni.caltech.edu>
>To: mod1-at-pupman-dot-com
>Subject: Re: Tube Coils (fwd)
>
>Richard:
>	Have to check my reference library here, but think you 
>are wrong about the 304TL and 304TH.  Difference as I remember
>it is in amplification factor (Low and High).  Also pretty near
>positive both those tubes use thoriated filaments.  Will check
>and apologize if I'm wrong!
>Ed
>
>
Ed,

Some of what you say may be right for later situations, but in Pulse
Generators page 95 they state that oxide filaments allowed 3-5 time the
current carrying capacitiy of the thoriated filament!  However, and here is
the problem,  With really high currents in pulse form the oxide filaments
sparked badly at the high voltage, high pulse current levels.  Thoriated
Tungsten did not.  Second,  The oxide filament show ed  strange problem also
in that during the pulse the current would drop dramatically.  The cause was
surmised to be "cathode fatigue".  This doesn't happen with the thoriated
tungsten filaments.  They beefed up the Thoriated fils in the 304 TH for
more emission and higher fil current.  The 304 TH was a radar tube with
special highend current pulse advantages of its sister 304 TL 

Such tubes were used in "hard pulsers" where complete control over the pulse
width and duration were mandatory.  The H2 thyratrons were much better in
every respect except wide latitude control.

Richard Hull, TCBOR