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Re: [Amps] Time for New Power Meter

To: amps@contesting.com
Subject: Re: [Amps] Time for New Power Meter
From: "Roger (K8RI)" <k8ri@rogerhalstead.com>
Date: Mon, 04 May 2015 02:41:47 -0400
List-post: <amps@contesting.com">mailto:amps@contesting.com>
On 5/3/2015 8:16 PM, Al Kozakiewicz wrote:
>From Bird's website: http://askbird.birdrf.com/afmmain.aspx?faqid=110

Al
AN2ZY


To suggest +/- 125 Watts anywhere on the scale, for a 2500 Watt range, simply 
does not make sense and it would make a total mockery of the using the 
instrument as a power measuring device.

That it does.  IOW, when on the lower end of the display, you are looking at 
ridiculous accuracies of +/- 50%, or even more.  With the Bird the wide range 
of slug selection should let you measure near the top end of the scale for 
accuracy.


73

Roger (K8RI)

73, Alek.
VK6APK

On 4/05/2015 7:19 AM, Joe Subich, W4TV wrote:
By Joe and Roger's interpretation, the reading anywhere on the scale
could be off by +/- 125 watts, even at very low readings. Do you
really think that is what Bird meant?
Yes, that is *exactly* what Bird meant.  The specifications in my Bird
Model 43 Instruction Book say: "Accuracy - +/- 5% of Full Scale
Power".  If *your* interpretation were correct it would say "+/- 5% of
indicated power" but it doesn't.

73,

    ... Joe, W4TV


On 2015-05-03 6:35 PM, Bill Turner wrote:
------------ ORIGINAL MESSAGE ------------(may be snipped)

On Sun, 03 May 2015 08:44:10 -0400, W4TV wrote:

No, Roger is correct.  Bird's specification is 5% *of full scale*.
That means the Bird's accuracy is +/- 125 Watts *anywhere* using a
2500 Watt element.
REPLY:

Total nonsense. Manufacture re specify "full scale accuracy" only
because they do not guarantee linearity and accuracy below full scale.
In other words, the accuracy is guaranteed only at full scale and
nowhere else.

By Joe and Roger's interpretation, the reading anywhere on the scale
could be off by +/- 125 watts, even at very low readings. Do you
really think that is what Bird meant? A reading of 10 watts could be
off by +/- 125 watts? Or a reading of 125 watts could actually be
zero?

73, Bill W6WRT
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