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[Amps] Alpha vs Henry

To: <amps@contesting.com>
Subject: [Amps] Alpha vs Henry
From: "Jim Thomson" <jim.thom@telus.net>
Date: Wed, 6 Apr 2011 03:53:41 -0700
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Date: Wed, 06 Apr 2011 03:23:04 -0400
From: "Roger (sub1)" <sub1@rogerhalstead.com>
Subject: Re: [Amps] Alpha vs Henry

On 4/6/2011 12:47 AM, Fern wrote:
> You can eliminate a lot of that weight by using a switching power 
> supply. Fern   VE7GZ

True, but as we've gone through on here several times, it's not a simple 
matter to build a 2500 to 3000 watt switching power supply with good 
regulation, low ripple, and no noise.  It's done and the little Tokyo 
Hy-Power HL-1.5Kfx and larger amps are good examples.

73

Roger (K8RI)
<snip>

##  The classic 3300 vdc  no load switcher that you used  to see advertised in 
QST worked,
but here's the rub.  It was intended  for a SB-220, or similar amp.  The 
switcher had to have a 
MIN load on it at all times....Kablamo, poof, toast.  The normal 180ma  idle 
current  was not enough
for the switcher, it had to be increased  a whole bunch.  [ they probably ran 
zero bias] . 
Also, the switcher had to be shut OFF, when on RX.   Duno if it was capable of 
QSK .  Extra relays
had to be wired in with the stock T/R relays....such that when on RX, the extra 
relay would shut of the
switcher..asap. Otherwise, with no load at all on RX.... it would go off like a 
bomb. 

##  Continental, and other's, use switcher's for B+ supplies  for big  SW AM 
broadcast TX.   But they
consist  of 40 x switcher's in series.  They modulate the 40 x switcher's via 
fiber optic cables, so they all 
swing from zero volts dc..to  700 vdc.   Normal deal for AM operation, and is a 
hi-tech version of
plate modulation.   With no modulation, the tube has 12 kv on it.  Modulated, 
it swings  from 0  to
24-30 kv. 

##  I didn't know Tokyo hy-power was using switcher's  for  tube amps.  For a 
solid state kw Amp,
switcher's  would be ideal.  For a typ 2-4 kv  tube amp, it would be expensive, 
lighter, but more $$
than a conventional supply.  We installed  hundreds of these -52.8 vdc suppies 
at the local Telco...
and each one is rated for 3.6 KW CCS.  Five of em will easily fit into a 25" 
wide rack.  They are only
aprx 6.7" tall..and  12" deep, weigh nothing..and barely run lukewarm,when 
maxed out.
They also have a few other advanatges...like perfect power factor, which also 
implies no
harmonics on the 208/240 input side. They will also run just fine with 40-70 hz 
input freq on the same
208/240 input line.  The 240 vac  single phase versions we use at cell sites  
will run just fine with
input voltages  ranging from  170-316 vac.  The 208 vac version has similar +/- 
 specs. 

Jim   VE7RF
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