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Re: [Amps] Time for New Power Meter

To: AMPS <amps@contesting.com>
Subject: Re: [Amps] Time for New Power Meter
From: Alek Petkovic <vk6apk@bigpond.com>
Date: Mon, 04 May 2015 08:09:47 +0800
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Might I be allowed to suggest that Accuracy +/- 5% of Full Scale Power" means that the best accuracy they guarantee is that 5% at full scale.

At lower readings, it may still be 5% or it might be a little more. Whatever the figure might be, to cover their ass, the manufacturer is not going to make any guarantees other than at full scale.

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.

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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