[Amps] Can I cool too much the tubes or ants?

[Jim Thomson]

Date: Mon, 23 Aug 2010 19:41:14 -0700
From: "Hardy Landskov" <n7rt at cox.net>
Subject: Re: [Amps] Can I cool too much the tubes or ants?

To all :
Melting antennas is a very good sign since I am the last one to relate this 
story.

Circa 1957. San Fernando Valley, CA
W6HX, Ted Gillete builds a 20 meter amplifier for W6YMD using 2-- 4-1000D 
tubes. They run 7000VDC on the plate at 2 Amps. This causes the driven 
element to glow at the ends as neighbors knock on Bill's door to tell him 
there are invaders from outer space. Actually they worked many AP, VU, & 3B8 
that night. The antenna did not survive.
Anyway that's what was relayed to me.....
73 Hardy N7RT

##  That's called ...'corona'  and it's  an easy problem to fix.   With corona, you 
are just stripping electrons right out of the air.  A few methods that been used on the
tips of DE's is to use AL corona  balls.  Another method is anti-vibration loops.  Another
method is to use insert machined solid AL cylinders in the tips... with the ends of the 
cylinders ground off, and rounded..sorta phallic looking.  Another method is to  grind and round off
the sharp edges of the DE tips. HV acrylic spray...or corona dope can also be used on the last 6"
of the DE tips.  Plane silicone rubber rtv will also work.  The idea here is... if you put a barrier between
the HV points and the air... you can't strip electrons from the surrounding air... since the al  tips
are surrounded  by corona dope/rtv/ge spray, etc.   Being at high altitudes just makes the corona problem
worse. 

##  Ted, W6HX was a nice fellow.  I use to hear his station during the Nov SS   phone contest  all the
time during the mid-late 70's.  I  think it was WB6OLD/6  that used to operate Ted's station, during the contests. 
Dunno what happened to WB6OLD/6 . 

later... Jim   VE7RF