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[Amps] Drake L7E observations and question

To: Amps Reflector <>
Subject: [Amps] Drake L7E observations and question
From: Mark Hill <>
Date: Thu, 21 Jun 2007 09:22:18 +0100
List-post: <>

Well I finally took delivery of my Drake L7E yesterday.  Up against 
my HB efforts, I'm amazed at how small the thing is, yet it makes 1kW 
OK, at least on 80 m.

Many thanks to all those that provided me with mod. info by direct 
mail.  There are certainly a number of less than clever aspects to 
the L7's design - I particularly love the bias divider silly in the 
HV PSU that makes the thing boil its nuts off before the amp. 
actually pulls any anode current!  All the issues are fixable, 
however and, with the PSU being separate, there's plenty of room for manoeuvre.

So far, I have one question on those familiar with the innards of the 
amp.:  When I lifted the lid, prior to plugging it in, I noticed 
something that struck me as odd, namely the orientation of the plates 
on the load 'capacitor'.  I can understand why the designer chose to 
use a split-gang capacitor, however I would have thought that the 
plates in each of the two gangs should be in mesh by the same amount 
for any given rotation of the shaft?  On my amp, the plates in the 
two gangs are close to being at 180 degrees with respect to one 
another - i.e. when the one gang is coming fully into mesh, the other 
is headed towards being fully unmeshed.  With both gangs paralleled 
electrically for the low bands, which way should I turn the load 
control to load heavy?  Perhaps there is a nut on the shaft somewhere 
that needs attention - any ideas?



Mark Hill - G4FPH
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