http://elecraft.85.s1.nabble.com/Wattage-Draw-K3S-100-vs-KPA500-KAT500-for-UPS-tp7633842p7633846.html
3000W at 120V is 25 amps. He had better have a dedicate circuit. I believe if I had to run a dedicated circuit I would run a 220 circuit for the amp and put everything else on the UPS.
> On Aug 30, 2017, at 6:42 AM, Don Wilhelm <
[hidden email]> wrote:
>
> Bret,
>
> The power rating of a transmitter is the output power, not the input draw.
>
> If the overall efficiency is something like 33% (quite likely), then the input draw will 3 times the output power.
> The efficiency of an RF output stage alone is typically about 50%, but there are other circuits in the transmit section that must be added and brings the overall efficiency of the transceiver down even more.
> So yes, the input power required is about 3 times the output power.
>
> A KPA500 running on 120 volts just about maxes out a 15 amp circuit, and that is 1800 watts input. The K3 will need about 300 watts additional.
> That means your UPS should be rated at least 2500 watts, but 3000 would be more reasonable because it seems you have other gear in the ham station that needs to be supported as well.
>
> 73,
> Don W3FPR
>
> On 8/30/2017 7:16 AM, MaverickNH wrote:
>> As mentioned in another thread, I'm running my shack on a UPS that is rated
>> 1500va/900w. With my K3S/100 and other hardware plugged in on the same input
>> the UPS often max's out at 900W at < 100W on the K3S. Typically, the
>> baseline with K3S on RX is ~350W and it spikes over 900W with TX at 100W and
>> the UPS limits output. So it seems 100W isn't 100W.
>> I'm looking to switch in another UPS rated 2200VA/1320W, or 420W higher, for
>> use with the KPA500/KAT500 I just acquired from another forum member. so
>> from a 100W station to a 500W station. Might this work or is the increase in
>> watt TX not equal to the watt drawn?
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