Bird wattmeters, such as the model 43 thruline, are far from
accurate devices. They are spec'd to be +/- 5% of the full scale
reading of the installed slug.
That means for a 100W slug, the error band is +/- 5W!
If you happen to read 20W on the meter, the error band says your
true power could be anywhere from 15 to 25 watts!
As a comparison, an HP 432A wattmeter can achieve an ultimate
accuracy of +/-0.2% +/- 10uW.
-Chuck Harris
Don Latham wrote:
Amtronix did tell me that the power measurements were off, according to
some folks who had compared them to Birds. Of course the E's could be
calibrated. I don't have much below 30 MHz at present either. I sense
that there may be enough around to warrant a Yahoo or Google group???
Don
----- Original Message ----- From: "Bob Camp" <[email protected]>
To: "Discussion of precise time and frequency measurement"
<[email protected]>
Sent: Monday, February 01, 2010 6:42 PM
Subject: Re: [time-nuts] Test Equipment
Hi
The big question in my mind about these is how well they do below 30
MHz. Until I know I can trust them it down there, I'm not selling very
much stuff.
I have yet to find a data sheet from before 2000 when they shipped
with the sub-800 MHz stuff enabled. I get the impression that the
E8285's never quite did as well below 30 MHz as the 8920's do.
Bob
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