To: <amps@contesting.com>
> Date: Mon, 01 Jun 1998 00:07:40 -0500
>
> The standard Bird HF slugs like we all use are marked 2-30 mhz. I
> always figured that 1.830 mhz was close enough to the edge to not
> make any difference. Not so...there is a 10% error on the low side
> in the reading!
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
--
FAQ on WWW: http://www.contesting.com/ampfaq.html
Submissions: amps@contesting.com
Administrative requests: amps-REQUEST@contesting.com
Problems: owner-amps@contesting.com
Search: http://www.contesting.com/km9p/search.htm
|