[AMPS] Bird Wattmeter Error on all bands

[Phil Clements]

At 09:26 AM 6/1/98 +0000, you wrote:

>The standard Bird 43 meter meter and slug has a published error of 
>plus or minus 5% of full scale anywhere on the scale.
>
>(That's why a Bird often shows incorrect SWR readings when a high 
>power slug is turned around.)
>
>If you have a 2500 watt slug, and are reading 1500 watts forward 
>power into a pure 50 ohm load, the actual forward power is anywhere 
>from 1625 watts to 1375 watts if the meter is within tolerance. + or 
>- 5% of 2500 is + or - 125 watts, and that is the tolerance ANYWHERE 
>on the scale ANYWHERE over the slugs range.
>
>If the a Bird 43 indicates 150 watts reflected power with a 2500 watt 
>slug, the actual reflected power can range from 25 to 275 watts. 
>
>73, Tom W8JI
>w8ji.tom@MCIONE.com


Yes, Tom, your statement is very evident in all Bird publications. You
missed my point...in ADDITION to the +/- 5% error, you must add ANOTHER
10% to the power reading when using a 2-30 mhz slug below 2 mhz.  Worst
case at 1.8 mhz with a 2-30 mhz slug is a 15% low reading.

(((73)))
Phil, K5PC

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