toroids are ft50-43,If its inline from my atu and diawa meter,Both power and swr track more or less the same on both meters,over about 5 watts if i adjust the atu for a 3-1 missmatch on the diawa,the homebrew one reads about 2-1 max and stays like that,even if i tune for a 10-1 swr,it tracks fine bellow 5 watts ok tho,is it because there is no shieldng separating the toroids?,there is only about 35mm separation and they are in the same plane,cheers.+73.
How to align an SWR meter.
1. Connect 50ohm load to the OUT and a transmitter to the IN and apply the maximum power the meter is going to see. 5w, 100w, 1 bazillion w. ETC.
2. Adjust the FWD power pot for maximum deflection on the FWD meter.
3. Reverse the IN and OUT connections
4. Apply power again and this time adjust the REF pot for maximum deflection.
If you have a 3:1 load, connect it and it should read 1/2 scale on both meters.
JOB DONE.
Again, this has to be done at the MAXIMUM power and will make the readings at MINIMUM power slightly off. It sounds to me like you have aligned the meter at 5W and then at 100W wonder why its reading wrong.
An FT50 sized toriod is fine to about 1KW in an SWR application. Take a look in any commercial SWR meters, they use essential a stack of 2 FT37 size toriods. The issue has nothing to do with saturation. Though, shielding the RF portion from the meter portion should be a priority. Put the bridge in a metal box and the meters outside that box and it should be fine. Just align it right.
Also PICTURES of what you have build and done actually help. The link to the schematic is useless in this case if its user error rather in construction. We are not mind readers. If its all just flapping about in the breeze and you have wires everywhere, all bets are off and it could be anything. Put it in a metal box first, then align it.