Or if you don't want to concern yourself with different slugs for different
frequencies and power levels (other than UHF)...sell your Bird wattmeter and
all the slugs and get a LP-100A which has NIST traceable calibration and
typically reads +/- 3% of the power reading from 1 W to 3000W ....and you
get peak or average reading as well as many other nice features...
Call me biased -- because I have two of them...but if you want to learn
more... http://www.telepostinc.com/lp100.html 73 de Greg-N4CC
-----Original Message-----
From: topband-bounces@contesting.com [mailto:topband-bounces@contesting.com]
On Behalf Of Tom W8JI
Sent: Saturday, June 30, 2012 5:25 PM
To: topband@contesting.com
Subject: Re: Topband: QRP and Bird 43 Watt meter help
> Many years ago at 4U1ITU I found the Bird 43 grossly underestimated
> the power output on 160, rather embarrassing at the temple of
> regulation.
If that was the case, they had a bad slug. The rating of the Bird 43 and
standard slug is + or - 5% of full scale anywhere on the scale within the
range of the slug, but it does not go far out of tolerance just 10% below
the low end of the specification range.
A 250-watt 2-30 MHz slug will read close to spec on 160 meters. If it is way
off on 160, you can bet it is way off on 80 and 40 meters, too.
- or + 5% means acceptable error is 12.5 watts low or high anywhere on the
scale, although normally when freshly calibrated they are much closer than
that. I would not expect a 250 watt slug to be more than 10-15 watts off on
160 meters, although the most common calibration failure is low reading. The
low reading error almost always comes from the calibration pot making a high
resistance connection to the wiper, meaning the slugs that go bad will age
terribly low in reading. About 30% of my Bird slugs fail in ten years,
despite very rarely being handled or used.
People need to remember the accuracy specs, and use slugs that keep the
meter well up the scale if accuracy is important.
73 Tom
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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UR RST IS ... ... ..9 QSB QSB - hw? BK
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