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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