It's kinda' hard to beat numerical digits when you want the best possible
resolution displayed. By the way Phil, I should re-phrase my earlier
wattmeter display, even with the set limitation on resolution. I prefer a
Here's a link to N8LP's article in QEX. Accuracy is highly dependent on
Thanks for your comments. And, in followup, if Elecraft were to make
method, other then LEDs, would be required. I think a high-resolution
LCD with nice color graphic renditions of power information. OK, sort
> Phil,
>
> With each LED representing 100-watts on the 2KW scale, it may be of some
> help to go from 10% to 5% in accuracy, but in the case of the W2, the
> display resolution is limited to 50-watts in between mid power ranges
> (e.g.,
> 250-watts) but a display of 200-watts with two LEDs showing may actually
> mean 151 watts or 249 watts.
>
> 50-watts is mid-way between any two LEDs at the 2KW range and I'm making
> an
> assumption that levels less than any 50-watt range (e.g., 240-watts) will
> result in the preceding element being lit which shows 200-watts. If it's
> more than the mid point (e.g., 260-watts) then the next LED should be lit.
> So, at the low-end of the W2's range at say the 200-watt level, the meter
> can at best resolve to only 50/200 = 25% and seemingly 100/200 = 50% at
> worst (using the 149W to 249W example). I don't want to confuse
> resolution
> with accuracy but the two parameters go hand-in-hand. That said, I see no
> real benefit of going from 10% to 5% in accuracy when resolution
> deficiencies can easily mask the error in accuracy. I may be completely
> wrong with the manner in which the W2 resolves, so someone set me straight
> if my assumptions aren't correct.
>
> You asked the question about what it takes to achieve better accuracy.
> You
> may want to read N8LP's excellent article in QEX from a few years ago,
> along
> with articles from Warren Bruene, Roy Lewallen, John Grebenkemper, and
> others who have published on the accuracy subject.
>
> Paul, W9AC
>
>
> ----- Original Message -----
> From: "Phil Hystad" <
[hidden email]>
> To: "Elecraft" <
[hidden email]>
> Sent: Wednesday, December 09, 2009 7:51 PM
> Subject: [Elecraft] W2 Questions
>
>
>> A few questions about the W2 meter:
>>
>> 1. The posted accuracy is +- 0.5 dB which I calculate as about +- 12 %.
>> Is this full scale accuracy and if so is half scale possibly more
>> accurate
>> or is this the most accurate the meter is likely to be. I am not even
>> sure if it makes a difference for full scale or half scale for a digital
>> meter so that part of my question may be moot.
>>
>> 2. What does it take to achieve an accuracy better then 5 % (for
>> example), and is it possible to achieve an accuracy of 1 % or better? I
>> am curious as to where the money needs to be spent in achieving such
>> accuracy. Is it in the directional coupler?
>>
>> 3. I am thinking that the company that can build the best receiver on
>> the
>> market (the K3) can also build the best meter. So, would Elecraft
>> principles consider a future super-accurate, best on the planet, amateur
>> radio RF/SWR power meter? Oh, I think a current meter would be cool too.
>>
>> And, I know that having meter accuracy is of little importance in ham
>> radio but there is some kind of deep seated quirk in me that wants
>> accuracy just for the heck of it. Certainly 5 % is achievable, right?
>>
>> 73,
>> phil, K7PEH
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