While Bird watt meters are rugged, revered and are the de-facto standard watt meters in both commercial and amateur circles, their accuracy leaves a lot to be desired. Unless recently calibrated, and used under specific circumstances (ambient temperature) their use should be more properly defined as relative output indicators. Look closely and you'll see that their accuracy is listed as +/- some percentage of a full scale reading for the slug you are using. With a 2500w slug, you could be hundreds of watts off and not know it. Granted, in amateur use, absolute accuracy really does not matter, but just keep this in mind when measuring what you see with your W2 or any other modern digital wattmeter when compared to a Bird.
Just because they read differently, there's nearly no justification to think the Bird is correct and your new wattmeter is not. 73, Bob W5OV -----Original Message----- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of NZ0T Sent: Saturday, January 02, 2010 7:51 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] W2 Wattmeter I'm very happy with my W2. There was an issue with an intermittent in the sensor cable but that was quickly resolved. It seems accurate enough to me on a subjective basis - I have no Bird to compare it to. As far as resolution goes the computer display resolution does rely on LED's and is a continuous bar with a switchable peak indication. This is only the 2nd version of the diplay software and I'm sure it will continue to improve. I have a friend that has the LP-100A and it's a really nice meter but I'm not sure I want to pay $120 more for it. 73 Bill NZ0T Phil & Debbie Salas wrote: > > "Those are good points about the trigger and perception of accuracy of the > W2. I have yet to see field test data of the W2 in regards to accuracy of > the > Wattmeter and SWR indications." > > According to the manual the W2 has an accuracy of +- 0.5dB typical > (nothing > about worst-case). This is 10-12% accuracy. Not as good as the > PowerMaster/LP-100A/Telepost class of wattmeters that use NIST-traceable > cal > equipment (which should get you more like 3-5% accuracy). Of course, > those > are $100-$150 more expensive than the W2. If you use the W2 LED display, > your perceived error could be greater than the 10-12%. As an example, if > you really have 100 watts and the W2 reads it 1/2-dB low, then possibility > only the 80-watt LED would light. So this would give you a 20% reading > error. > > Maybe the ARRL will do a review sometime soon. > > Phil - AD5X > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > > -- View this message in context: http://n2.nabble.com/W2-Wattmeter-tp4242517p4244535.html Sent from the Elecraft mailing list archive at Nabble.com. ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
