[Amps] Memories of Many 11 Meter Amps

[Jim Thomson]

Date: Thu, 23 Feb 2017 15:29:28 -0800
From: Tom Osborne <w7why1 at gmail.com>
To: amps at contesting.com
Subject: Re: [Amps] Memories of Many 11 Meter Amps

WRL Galaxy amp had a bank of 10 sweep tubes in it for 2k input.  Real
touchy on 10 meters :-) 73
Tom W7WHY

##  1000 volts at 2A of plate current for 2 kw dc input.  Thats  20A of circulating current
in the poor bandswitch + tank coils.   Plate load Z =  294 ohms.   That would require massive
amounts of C  for both the tune and load caps..and a tiny value tank coil..but with huge gauge wire
+ tubing..to handle the current.   To get around that gong show, they used a V divider, and stepped
the plate load Z  UP  to something they could actually build a pi net around.   Then try and balance
the drive power between 10 tubes, then tweak the idle current for each individual tube.  Then try
and get each tube to draw the same current.   No thanks.


##   It all worked though.   Nobody puts 10 x engs  in their pick up truck,  1 is  good enough.
Not big enough, get a bigger eng.   Single tube GG triode amps  are easy to  trbl shoot. 
2 tubes max. 

##  OK Roger, race out and get one of those  OM power, FCC approved,  4 kw pep output
auto tune amps, with the pair of chinese  FU- tubes in it.  Bargain at $7k... and way less for the
manual tune version.  Weighs 100 lbs, comes with a pair of 3 kva  CCS rated torroid plate
xfmrs.  Then evaluate it for us.  2.5 kw CCS  RTTY + FM,  4 kw pep out  SSB  +  CW.
That should be  plenty of head room for anybody.  Array solutions sells both versions.   Tubes are cheap.

Jim  VE7RF