Date: Thu, 7 Nov 2019 18:40:38 +0100
From: <dj7ww@t-online.de>
To: "'Jim Thomson'" <jim.thom@telus.net>, <amps@contesting.com>
Subject: Re: [Amps] GS35B Amps Common Problem / few more comments
<I dont think so und would never allow less then 7V and rather stay above
<7.1V.
<With 6.5V you wan?t get enough heating power for the cathode.
<73
<Peter
-----Original Message-----
From: Amps [mailto:amps-bounces@contesting.com] On Behalf Of Jim Thomson
<Fil V set for 6.5 vac. Tube will last forever.
## The procedure we used was to 1st operate the NEW / REBUILT tube at
rated fil V.... measured
at the socket... for the 1st 200 hrs. Emission increases the 1st
150-200 hrs..where it reaches a peak.
## At that point, fil V is reduced until PO.... JUST drops off by
a few watts. IE: ....knee effect.
## say 1500 watts..... then reduce fil V till PO down to 1490.
## Then increase fil V..till 1500 watts.
## Then increase fil V by another .1 or .2 Volts. Then you are
done.
## Trick is.... dont reduce fil V by more than 15%. .85 X 7.5 V
= 6.375 I measured Fil current at 7.5 V to be exactly 50.0 Amps.
At 6.643 V.... current drops to 44.28 Amps. ... = 294 watts.
## 3000 tube is rated at 2.5 A CCS plate current.
## Typ the 3000 is run at 1A to 1.5A New tube..after 200 hrs
has bucket loads of excess emission.
## On the 6000 tube, rated fil V is 7.0 V. Buddy has been running
6.2 V on the cathode for 12 years now,
with zero drop in PO. 6000 rated at 3.5 A CCS plate current. Its
been run at 2.7 A for 12 yrs. Hr meter on
input to variac. >9000 hrs so far.
## with my incoming line voltage all over the map, and also dropping
on TX, I use a sola constant V xfmr to feed the input of the
small 5A variac...... which feeds the fil xfr.
Jim VE7RF
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