Since this has historically been a can of worms, (it created a firestorm of emails back in 2010 on a yahoo group between W5DXB, R. Fry, K1TTT, W7EL, and Owen Duffy, then VK1OD) I want to introduce an authority on power measurement. Agilent (now called Keysight) has a three part document that talks about power measurement, the usefulness of these documents depends upon your level of understanding and application but since we can all add and subtract, eqn 2-21 of this document indicates that the power delivered to the load (with all of the assumptions listed) is the forward (incident) power minus the reflected power.
http://cp.literature.agilent.com/litweb/pdf/5988-9215EN.pdf Myron WVØH Printed on Recycled Data > On Jan 13, 2015, at 1:45 AM, David Woolley <[email protected]> wrote: > > As well as not all the reflected power being re-reflected, the forward power > measured by the coupler is not the first time forward power, but the sum of > all the re-reflected power, as well. > > -- > David Woolley > Owner K2 06123 > >> On 13/01/15 01:19, Fred Jensen 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 > >> >>> 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]
