http://elecraft.85.s1.nabble.com/Wattage-Draw-K3S-100-vs-KPA500-KAT500-for-UPS-tp7633842p7633851.html
Put the radio and other shack items on the 2.2kw UPs. Buy a separate 220
I did not consider the efficiency of the power supply. The 600W was the
transmit. So as you state, if the power supply is only 50% efficient, then
> On Aug 30, 2017, at 7:33 AM, Bob McGraw K4TAX <
[hidden email]> wrote:
>
> Tom, Bret et al;
>
> I agree with you ........... something is not right. I see my K3S draws
> about 1.2 amps DC on receive. at 1.38 volts that's about 17 watts. If my
> supply is only 50% efficient, that's 35 watts. I can't understand where
> the 350 watts would be used unless other equipment is being used. And I
> agree that transmit is 20 amps at 13.8 volts or 276 watts. Again with a
> supply that is 50% efficient, that is only 550 watts or so. Certainly no
> where near the "over 900 W".
>
> Perhaps the computer, monitor, lamp, printer and other ancillary
> equipment is part of the load on the UPS. It is more likely the inductive
> load on the UPS is creating an issue with the power output indication.
> Although that doesn't explain the UPS shut down or fold back in power.
> One other issue regarding the UPS, is the output Pure Sine Wave, Modified
> Sine Wave or Square Wave? This may have a significant impact on its
> function with various types of loads.
>
> One way to evaluate the indication of the UPS output is to use an
> incandescent bulb of 150 to 300 watts. They are resistive and reasonably
> accurate with regard to power consumption. Don't use any of the bulbs
> which are "equivalent" rated ones. I use this method as a load when I've
> had to repair any of my DC to AC inverters.
>
> 73
> Bob, K4TAX
>
>
> On 8/30/2017 6:50 AM, KQ5S-Tom wrote:
>> Something is not right. If your UPS is showing 350 with the K3S at idle
>> and over 900 on transmit that is a difference of close to 600. The K3S
>> draws 17-22 amps at full key down and 100 watts. Assume 20 amps at
>> 13.8V. That is only 276. You are showing double that.
>>
>> ---------
>> KQ5S-Tom
>>
>>
>>
>>
>>> On Aug 30, 2017, at 6:16 AM, MaverickNH <
[hidden email]> 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?
>>>
>>> BRET/N4SRN
>>>
>>>
>>>
>>> --
>
>
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