Tom,
>
I got into a frustrating thing with the ARRL lab when they reviewed an
AL1200 amp. They used an RMS metering and regulating system, and they had
terrible peak clipping caused by soft power lines and a bad regulator in the
lab. It took forever (after the review was published) to get the ARRL to
understand how power lines work. It was worse than dealing with a layman,
because they kept telling me "we paid $30,000 for our regulator, and it is
rock solid" or something equally stupid.
>
For that kind of cash I am surprised they did not get an industrial quality
inverter-type UPS. For these, the mains are used only to charge the
batteries. The inverter generates mains power from the batteries.
Keith
-----Original Message-----
From: towertalk-bounces@contesting.com
[mailto:towertalk-bounces@contesting.com] On Behalf Of Tom Rauch
Sent: Monday, January 24, 2005 10:07 AM
To: towertalk@contesting.com; Pete Smith
Subject: Re: [TowerTalk] Shack wiring
> My entire shack is on a single 110V circuit (separate 220
for the
> amplifier).
You mean 120. The USA standard (last time I looked) was 120/240.
Recently I have begun to get low voltage warnings (104.5
> volts) from my UPS in the morning, and so have put a
digital voltmeter on
> the circuit. With no load except for the computers (2),
the UPS and the
> table light, voltage right now is 108.7.
Too low. Almost everything is cenetered around 120v +- 5% Mine is 123 or so
normally.
My two radios (on receive) cause
> the voltage to drop about .4 volts. When the voltage is
running low, I
> typically see 104.7 or 104.8 without the radios, so adding
them to the load
> sets off the UPS.
Wow. I would guess a typical HF radio might draw an amp or less from the
mains on receive. That would mean you have an ESR of .2 ohms in the mains.
That's pretty bad.
> Two questions, I guess -- is the voltage drop with loading
I describe above
> roughly what you'd expect? If necessary I can dig out the
standby power
> requirements for the two radios. And second, what is the
US spec for line
> voltage? The power company is coming out to investigate
and I'd like to
> know where I stand.
For capacitor input supplies, you need to measure PEAK voltage....not RMS. I
got into a frustrating thing with the ARRL lab when they reviewed an AL1200
amp. They used an RMS metering and regulating system, and they had terrible
peak clipping caused by soft power lines and a bad regulator in the lab. It
took forever (after the review was published) to get the ARRL to understand
how power lines work. It was worse than dealing with a layman, because they
kept telling me "we paid $30,000 for our regulator, and it is rock solid"
or something equally stupid.
When dealing with a capacitor input supply, you need a true peak reading
meter. When dealing with things that respond to heating like tube filaments
and lamps, you need to know the true RMS.
The same meter (and the same voltage regulator or monitor) won't work for
both.
I don't know what your UPS is actually measuring and watching, but odds are
it is nether peak nor RMS. It probably, like most cheap (and some very
expensive things), is not reading what it should actually read.
So you need two meters Pete...you need to measure the true peak and you need
to measure the true RMS. Capacitor input supplies run off the peak, and are
more sensitive to line ESR at a given power load than resistive loads like
choke input supplies or filaments.
73 Tom
_______________________________________________
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_______________________________________________
See: http://www.mscomputer.com for "Self Supporting Towers", "Wireless Weather
Stations", and lot's more. Call Toll Free, 1-800-333-9041 with any questions
and ask for Sherman, W2FLA.
_______________________________________________
TowerTalk mailing list
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