[Amps] Tl- 922

gudguyham at aol.com gudguyham at aol.com
Wed Jul 15 11:45:16 EDT 2020

Not entirely true!!  The CT of the filaments is tied in between the two tubes back the the filament transformer.  If one filament opens up the other tube will stay lit.  Check the schematic.  By connecting the CT like they do any imbalance current flows back so that one tube doesn’t drawn more current.  The problem is if one tube goes out it puts a large current on the CT and it can overheat L20, therefore it is not a good idea to run the amp with only one tube.  The filament transformer can be smaller and lighter with 10volts.  

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 On Wednesday, July 15, 2020, Jim Thomson <jim.thom at telus.net> wrote:

Date: Wed, 15 Jul 2020 03:52:26 -0400
From: Artek Manuals <Manuals at ArtekManuals.com>
To: "amps at Contesting.com" <amps at contesting.com>
Subject: Re: [Amps] Tl- 922

<Ahh I see now that there ( at least) three R7's on the schematic one on 
<HV Rectifier Stack X43-1290-01 and one on the Meter Shunt board 
<X54-1300-10 and one on the main chassis !

<As a previous poster noted remove the tubes one at a time



##  Problem is... the  fils are wired in  SERIES !  Remove either tube, and the remaining  tube  will not light up.
Henry radio did the same thing on their  2 x 3-500Z amps.  Fils in series is not a smart idea.  And for what,  so they can use
14 gauge magnet wire..instead of  10 gauge on the  bifilar  fil  choke.  They saved all of a few pennies. 

##  That grid to fil short happens..after the fil has heated up.  You wont see the short, with tube out of socket.

##  The  TL-9222  uses a 10 V  @  15A  fil xfmr.  So dont short out one  fil...or the remaining tube  will have a full 10 V  on it. 

Jim  VE7RF

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