Jim
Your SWR will only be the same on all measurement devices if you are testing into a 50-ohm resistive load. You are testing on an inductive load that is showing a 1.4:1 SWR, and there is nothing wrong with that SWR Reading, although it will actually be higher if you read it at the antenna.
You can read about it in this document by the ARRL. https://www.arrl.org/files/file/Technology/tis/info/pdf/q1106037.pdf
SWR readings vary across the feedline and that is what you are seeing.
As for the power producing tuner? You can't cheat physics.
Mike va3mw es HNY
Hi Jim
Sorry I missed it. :). Sometimes you just never know.
With an SWR mismatch, your power will also be inaccurate. It is only accurate on a 50 ohm resistive load.
73
It is all about standing RF waves (waves that do not move in the feedline) and constructive and destructive interference.
I was trying to find a good article on it, but I am still looking.
In college, we built a test jig at 100Mhz that had jumpers in 1/4 wave increments. (ok, I built it and I feel like I soldered about 100 connectors on all the different cables we required). We then measure the RF power along the feedline on a 50 ohm load and on a 25 ohm load. I wish I still had the notes from it. :)
Jim - Even with running into a 50 ohm RF load (Palstar DL5K) I see differences. My PG-XL and TG-XL (with latest updates) typically indicate power level indications which are fairly close (~ 30 watts difference @ 1kw), while my LP-700 shows 200-300 watts lower. ˉ\_(ツ)_/ˉ
Butch, KF4HR
Jim, I know you mentioned your system is relatively flat but couplers for LP 700 should be before amp and between amp and tuner.
Using Flex TUNE button, I see about a 5% difference in the PG XL, TG XL, and high power LP700 coupler with a 2000 watt 50 Ohm load on output of tuner and tuner in bypass.
The LP700 reads substantially higher PEP as it has much faster sampling rate for power sampling. Also the latest beta firmware for LP700 (not on their site) adds input power, output power and amp gain on the Trap/waveform screen.
73
Dave wo2x
