A better example would be to use a 100 Ohm dummy load and match it with a tuner. Then measure the heat generated by the load. It should be 100W, minus any losses in the tuner and transmission line.
wunder K6WRU CM87wj http://observer.wunderwood.org/ On Jan 12, 2015, at 9:26 PM, Vic Rosenthal <[email protected]> wrote: > Here is an experiment to show what I mean. > Take a transmitter and connect it to a 50 ohm dummy load through an antenna > tuner. Put a wattmeter between the transmitter and the tuner. > Now adjust the transmitter for 100 watts output and the tuner for 1:1 SWR. > The meter reads 100W forward and zero reflected power. > Now adjust the tuner for an SWR of about 2.5:1. The wattmeter will show > forward power of about 120 watts and reflected power of about 20 watts. Did > I increase the real power output of my transmitter? Did I make my signal > stronger? No. > I want a wattmeter that has an option to indicate 100 watts in this situation. > > Vic K2VCO /4X6GP > >> On Jan 13, 2015, at 6:56 AM, Walter Underwood <[email protected]> wrote: >> >> No. That is wrong. Forward and reflected are aspects of the standing wave, >> not power delivered. —wunder, K6WRU >> >>> On Jan 12, 2015, at 8:53 PM, Vic Rosenthal <[email protected]> wrote: >>> >>> What I want is just forward - reflected. Neglecting losses, this is what >>> the tx is 'delivering'. In real life somewhat less gets to the antenna. >>> >>> Vic K2VCO /4X6GP >>> >>>> On Jan 13, 2015, at 3:19 AM, Fred Jensen <[email protected]> wrote: >>>> >>>> Well ... sort of. Some of the reflected power heats up the ATU and/or PA >>>> depending on the match it sees [actually, some of the forward power does >>>> too, tuners have forward losses]. "Delivered Power" is somewhat difficult >>>> to calculate. Working into a matched, non-reactive load [common for AM >>>> broadcast, at least a number of years ago], it's "I squared R" where R is >>>> the radiation resistance of the antenna ... and some minor conductor >>>> losses in the antenna. Things get pretty sticky if it's not a matched >>>> load. >>>> >>>> 73, >>>> >>>> Fred K6DGW >>>> - Northern California Contest Club >>>> - CU in the 50th Running of the Cal QSO Party 3-4 Oct 2015 >>>> - www.cqp.org >>>> >>>>> On 1/12/2015 4:46 PM, Phil & Debbie Salas wrote: >>>>> >>>>> Actually, "delivered power" is pretty much what you are measuring. >>>>> Remember that reflected power is re-reflected by the source and adds >>>>> back into the forward power. So in your example, you are transmitting >>>>> 1200 watts, having 200 watts reflected, then the 200 watts is >>>>> re-reflected by the source giving you the 1200 watts. Of course, there >>>>> will be transmission line SWR-related losses. >>>> >>>> ______________________________________________________________ >>>> 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] ______________________________________________________________ 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]
