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[Amps] Use of temperature paints and crayons on tubes

Subject: [Amps] Use of temperature paints and crayons on tubes
From: "John Lyles" <>
Date: Wed, 29 Aug 2007 22:47:10 -0600
List-post: <>
Bob - Tempilaq, or Omegalaq when it is bought from Omega, can be used to 
measure your 4-1000A seal temperatures if applied carefully. I have not used it 
with glass tube envelopes, only ceramic/metal. Several things must be done. 
Make sure the paint is liquid enough to apply a thin film of a coating. Make 
the marks very small. If the stuf is thickened, then appy their approved 
Thinner and shake well. You don't want a thick dot or blob. As you know, when 
the temp is reached, the paint will run and change color/appearance. I usually 
use 125, 150, 175, 200 deg C paints when measuring power tube seal temps. Apply 
them in several locations around the tube, in clusters of the colors that you 
can later look at and identify which has run. This might identify hot spots 
such as when using connections for RF cavities which only contact one side, 
etc. Try not to bridge over large portions of the tube, just keep it in small 
clusters. I am not certain how glass will handle the paint on it, 
 but my
guess is as good as ceramic if you keep the dots or smears very small, <3/16 
inch, perferable smaller. Put the dots near where electrodes poke through the 
glass. Even better put them on the metallic posts sticking out. 


> Message: 8
> Date: Mon, 27 Aug 2007 17:27:57 EDT
> From:
> Subject: [Amps] temperature
> To:
> Message-ID: <>
> Content-Type: text/plain; charset="US-ASCII"
> I purchased a used HF amp with a 4-1000A but no blower.  To verify  that the 
> blower I have is adequate I would like to measure seal  temperatures.  I 
> believe that this can be done using Tempilaq.  How  successful is doing that? 
>  The 
> maximum seal temperatures are 150C for the  base and 200C for the plate.  To 
> be conservative, I expect to use tempilaq  laquer values well below those 
> temperatures.  What values of temperature do  you usually experience with an 
> adequate blower?  If you have the model of  such a blower that would be 
> helpful too. 
>  Thanks.  Bob W7LR
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