----- Original Message -----
From: "Tom W8JI" <w8ji@w8ji.com>
To: "Roger" <sub1@rogerhalstead.com>; <rbonner@qro.com>;
<amps@contesting.com>
Sent: Monday, July 16, 2007 1:17 PM
Subject: Re: [Amps] ALPHAs and momentary power outages
>I think you are getting terrible advice here.
>
>> OK, you are talking VA, I was alking watts. If you look at
>> the UPS ratings
>> it will have both with watts usually being half or less
>> than the VA rating
>> and the usual math will not get the equivelant VA to watts
>> rating.
>
> Everyone better be careful here.
>
> VA is the volts times amperes. It is not watts, and connot
> be turned to watts unless you know power factor.
>
> Power factor on a cap input power supply is terrible, and
> the better the supply components the worse it gets. Power
> factor is caused by the short period of load on the mains as
> the capacitors charge on every half cycle. The peak current
> can be 50 amps or more with a good quality supply that draws
> only 15 amps! That means the VA load would be 50 times 240,
> or 12 kVa for a 3600 watt amplifier load.
>
FWIW, the switch mode regulators the Honda EU2000i generators
will handle the capacitive input of a linear amplifier quite nicely
(at least they have so far for me). I've run a Drake L-7 from a pair of
EU2000i's
in parallel at 1000 to 1100 watts RF output CQing all night long on
160 meters with no problems to date. The Honda's are rated at 2000VA
each (4KVA when in parallel). The Honda's use true sine wave inverters
and voltage regulation is very good (better than my line regulation at
home). Mind you, this is with the amplifier wired for 120VAC operation
(the EU2000i don't have a 240VAC output).
OTOH, I tried running a Henry 2002 (single 3CX800) from a conventional
(i.e. non-inverter) Honda 2KW generator once, and the regulation was
horrible (best I could do was about 400 watts output).
73, Mike W4EF..............................................
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