If you really want precision, use a water cooled load. Measure the flow rate and input and output temperature. You can precisely calculate power.
Sent from my iPad > On Jul 23, 2019, at 9:38 AM, Bob McGraw K4TAX <[email protected]> wrote: > > Since power meter systems are calibrated at a known impedance {usually 50 > ohms}, and they are voltage sensing devices, any deviation from the > calibration value will introduce an error in power indication. It just > depends on how precise one prefers to be with power measurements. > > 100 watts into 50 ohms is 70.71 volts > > 100 watts into 55 ohms is 74.16 volts > > 100 watts into 45 ohms is 67.08 volts > > 73 > > Bob, K4TAX > > >> On 7/23/2019 5:43 AM, CUTTER DAVID via Elecraft wrote: >> I often wonder just how useful a precision dummy load really is in the >> amateur service. I picked up home brew dummy load at the club the other >> day. It measured 57ohms dc and comprises 4 wire-wound resistors attached in >> a cluster across the end of the coax. After lots of disparaging remarks I >> put it on the VNA and it didn't look at all bad out to 30MHz: nothing over >> 1.5:1 and no spikes or dips to indicate resonances. I'll have to do it again >> and make a print-out for posterity. >> I've heard that salt water in a bucket works after a fashion. >> So the question is: how good do you need it to be? >> David G3UNA >> >> >>> On 22 July 2019 at 23:58 "hawley, charles j jr" <[email protected]> >>> wrote: >>> >>> >>> Used Bird Attenuator is a good deal. >>> >>> https://nm3e.com/AttenuatorSampler.htm >>> >>> Then you’ll have a sample to plug into your counter or scope >>> >>> Chuck Jack Hawley >>> KE9UW >>> >> ______________________________________________________________ >> Elecraft mailing list >> Home: http://mailman.qth.net/mailman/listinfo/elecraft >> Help: http://mailman.qth.net/mmfaq.htm >> Post: mailto:[email protected] >> >> This list hosted by: http://www.qsl.net >> Please help support this email list: http://www.qsl.net/donate.html >> Message delivered to [email protected] > > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[email protected] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to [email protected] ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
