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Re: [Amps] GS-35B tube issue

To: Steve Wright <stevewrightnz@gmail.com>,amps@contesting.com
Subject: Re: [Amps] GS-35B tube issue
From: Paul Baldock <paul@paulbaldock.com>
Date: Mon, 26 Dec 2016 13:52:05 -0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
At 11:59 AM 12/26/2016, Steve Wright wrote:


You are a little light on details with regard to hours, drive, output, and bands of operation - probably for a good reason. ;)

Steve

Probably on the existing tube less than 100 hours, drive 10W of 100% modulated AM (yes you remember AM), output 300W of carrier 1200W PEP with modulation, Plate current carrier only 300mA until modulated, mostly 40M and 15M.

- Paul



On 27/12/16 06:00, Paul Baldock <paul@paulbaldock.com> wrote:
I have a home brew GS-35B amp built around 5 years ago. I run about
4KV on the plate. I purchased 2 NOS tubes at the same time. Initially
when I built the amp I needed around 40V of bas voltage for idle
current of about 120mA. Over the next few years, and with little use
the idle current gradually rose and I gradually increased the bias
voltage to compensate and about a year ago at maximum available bias
voltage of 54V the idle current was about 200mA. At this point I
replace the first tube with the second tube, set the bias voltage at
40V and had an idle current of 110mA. Now a year later the idle
current has crept up to 200mA (at the same 40V bias).
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