[Amps] 3CX-3000A7 at 144

[Jim Thomson]

Date: Thu, 6 Feb 2020 22:48:39 +0000
From: Steve Thompson <g8gsq72 at gmail.com>
To: amps at contesting.com
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