I got my hands on a Bird Watt Meter and a suitable plug to use for 2 meters and 50 or so watts.
I am using it to check the SWR on my Maxtrac/plumbers J pole combo in the garage.
I measured 41 watts output and 1.5 watts reflected.
I have 50' of RG-8X.
I used a constant of 3.1DB/100' for the cable.
I used this site to calculate the SWR and got 1.75
Is that OK? Does that all make sense?