[Top] [All Lists]

Re: [Amps] 3CX-3000A7 at 144

Subject: Re: [Amps] 3CX-3000A7 at 144
From: Alek Petkovic <>
Date: Fri, 7 Feb 2020 10:02:16 +0800
List-post: <>
I've got a couple of 50Hz, 7.5V @ 53A, CT trannies here, from broadcast transmitters which ran the 3CX2500A3.

The gentleman looking for one, would be welcome to one of them for free.

Trouble is, that I'm in Western Australia and the shipping, to anywhere, would cost an arm and a leg.

73, Alek. VK6APK

On 7/02/2020 8:28 am, Jim Thomson wrote:
Date: Thu, 6 Feb 2020 22:48:39 +0000
From: Steve Thompson <>
Subject: Re: [Amps] 3CX-3000A7 at 144

<GS35B, 8877 and the like have separate cathode - they don't need a
<CT for the B- return. DC switcher supplies work just fine as long
<as they go into constant current rather than tripping out on overload.

<Steve G8GSQ

##  Points  well  taken.  The  GS35B  has  its  cathode internally bonded  to  
one  side of the  filament.
So a separate,  single  winding  choke  is  used  for the DC  return.   Just  
dont  let  the  B-  ever  go  open
on  you.

##  Moot  point  in  the case  of a 3CX-3000A7  triode.  A  fil  xfmr  with a 
CT is  readily  available,  simple  setup.
A  7.5  vdc  @  50A  switcher  is  no  easy  feat.....esp  with  the  major  
issues  of  inrush. Then  toss  in  RFI  from  the  switcher,
and the xfmr +  CT  looks  even  more  appealing.

Jim   VE7RF

Amps mailing list
Amps mailing list

<Prev in Thread] Current Thread [Next in Thread>