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[AMPS] 4CX15000

To: <>
Subject: [AMPS] 4CX15000
From: (2)
Date: Fri, 6 Jul 2001 07:09:23 -0700
>I have a 4CX15000 that I would like to trade for a 4CX5000.  Email me if
/\  The 4CX15,000A/8281 is quiet similar to the 4CX5000A/8170.  Both use 
the same socket, have handy handles, and have 7.5V filaments.   For the 
8281, the anode current, Filament current,  and voltage ratings are 
roughly a third higher than for the 8170.  This allows the user to 
produce up to about 1/2 of 1 S-unit (3db) more watts.  However, the 8281 
can be operated from a 8170's power supply with ease.  The major 
difference between these tubes is that different diameter chimneys are 
used.  Also, when switching tubes the neutralization and the brid bias V 
need to be touched up.  The big advantage of the 8281, is a freer-flowing 
anode cooler.  Thus, when an 8281is used at 8170 ratings, it can be 
cooled by a quiet slow-speed/1750 RPM blower.  However. the 8170 needs a, 
Much more noisy, high-speed/3450 RPM blower to ram air through it's 
narrow cooler.  
-   Both tubes can be rebuilt/recarburized and both make for an unboring 
project.  However, it is my opinion that it not a good idea to use more 
power than is needed to communicate.  Also, using such a beast to "win" a 
radio contest does not warrant a feather in one's war bonnet.  /  see my 
Website for info on designing tetrodes-with-handles/20db+ gain linear 

have fun, Rick.  

-  R. L. Measures, 805.386.3734,AG6K,  

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