[Amps] GS-35 being cantankerous

[Steve Thompson]

----- Original Message ----- 
From: Steve Maki <steve at oakcom.com>
To: <amps at contesting.com>
Sent: 23 June 2003 03:54
Subject: [Amps] GS-35 being cantankerous


> K8GM asked me to post this plea for help...
> 
> He is playing around with a GS-35, and so far hasn't been able
> to be happy.
> 
> The symptom is as follows:
> 
> As the drive is increased, at some relatively random point,
> the tube makes a single pop - he says it sounds like someone
> snapping their fingers. He sees no abnormal meter indication
> or change in output - in fact, the amp continues to operate
> normally. There's only one small problem - when the pop happens,
> it distorts the plate choke windings. They sort of get all 
> bunched up as if some large force tried to slide them along
> the form with enough force to stretch the wire and cause over-
> lapping. No fuse blows, and except for this occasional pop,
> the amp works great.
> 
> His supply is c. 3500V, and he's tried a couple of different
> chokes, both commercial and homebrew. It appears to be strictly
> a tube issue, rather than associated circuitry, but in our
> preliminary web search haven't come up with references to this
> problem.
> 
> What's happening here? Does the GS-35 need some kind of magic
> pre-conditioning? He has idled the tube at full voltage for a
> few hours, but that didn't do the trick.
There's some stuff about conditioning these tubes on SM5BSZ's website.

Steve