Tim,
Thanks for posting the manual URL. I went there in hopes of finding the
most important info that would tell the story - the schematic, but no luck.
In any event, what you say in your posting is all correct. For anyone not
familiar with a product designed to meet FCC Part 15 Class A performance,
keep in mind that "point of sale" terminals (such as gas pumps, cash
registers, and such) are all Class A devices, and those are the gizmos that
knock the heck out of your ears when driving in urban areas near banks, gas
stations, and large stores while monitoring 2m and/or 440 in your mobile.
Granted, it is not likely that the Sorenson power supply will produce VHF
and UHF racket like those computer-based devices (it is the data clock
signals and high speed data bus lines that radiate the noise), but it most
likely will produce most of its noise (radiated and/or conducted) in the MF
and lower HF region.
With general purpose switcher power supplies, another consideration is the
intended use. Because this is a fully programmable power supply, it would
be excellent as a test bench power supply, if you happen to have the 100
amp circuit to feed its input available. (That's mentioned in the manual.)
Yep - I suspect that the reason for such a stiff requirement is to avoid
nuisance tripping of lesser current-rated circuit breakers from the turn-on
current surge. Anyway, if the supply is intended to be used mostly as a
high current source at or near 13.6 volts, then beware because there is a
pretty good chance that the switching noise will be worse under that
condition. (Switching power supplies tend to get "quieter" as they get
closer to full rated load current.)
So, as a test bench supply, KD4E could go for it, since he probably won't
be operating a rig at the same time he's at the bench. However, if he
plans to run his ham shack from this beast, he should try something made
for the task, especially if he intends to operate HF. The Astron and MFJ
switchers are excellent, and they don't require 100 amp feeders! If
someone wants a monster 13.6 volt source, be sure to stay with a power
supply using linear regulators, not a switcher. How to tell: well, you'll
get a hernia or ruptered disc from trying to heft a linear supply rated for
around 2 kW of output. It will have a LOT of heatsink area, too. They are
hot and inefficient, but they are usually RF quiet. In any event, if there
is no need for voltages in excess of 15 volts or so, do not get a power
supply designed to provide 50 or more volts. A linear type will run very
hot at lower voltage settings and high load currents, and a switcher will
make a lot of RF noise at lower loads.
73, Dale
WA9ENA
Tim Groat
<tcgroat@mesanetw
orks.net> To
Sent by: rfi@contesting.com
rfi-bounces@conte cc
sting.com
Subject
Re: [RFI] Sorenson DCS 55-55 PS
04/07/2007 04:22 Clean?
PM
You can read the manual here:
<http://theelectrostore.com/datasheets/dcs55-55_nig.pdf> (warning: long
file!). On page 4, it says the power supply is certified to meet FCC Class
"A" emissions. In other words, it's going to make more RF noise than a
class "B" product, at least at some frequencies. If it passed class "B"
standards, they would almost certainly say so because that opens additional
sales opportunities.
Also take a look at the safety information on page 2. Among other things,
this unit needs a dedicated 208-240V AC power line similar to what you'd
need for a legal-limit power amplifier. That's to be expected, since this
*is* a 2.5kW power supply.
So I won't say don't use it--Sorenson is a respected company that make fine
industrial products. But do understand what you're getting into. Powering
an amateur radio transceiver isn't what they had in mind when they designed
and built this heavy-duty brute.
73,
--Tim (KR0U)
>kd4e <kd4e@verizon.net>:
>Anyone familiar with the Sorenson DCS 55-55 rack mount power supply?
>Are they RFI clean?
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