The RF source (your radio) has nothing at all to do with SWR.
SWR is a function of the impedance of the coax and the impedance of the antenna at its feedpoint. Nothing else.
I didn't see any mention of what you're using to measure the SWR - an external meter or the ones built in to the radios. If you're using the built-in meters, that's probably the source of the problem. NEVER use them except as a very rough estimate. Get a good external meter (doesn't have to be a Bird), and just use it. Forget about the built-in metering.
SWR is a function of the impedance of the coax and the impedance of the antenna at its feedpoint. Nothing else.
I didn't see any mention of what you're using to measure the SWR - an external meter or the ones built in to the radios. If you're using the built-in meters, that's probably the source of the problem. NEVER use them except as a very rough estimate. Get a good external meter (doesn't have to be a Bird), and just use it. Forget about the built-in metering.
...runna pile-up on 6m SSB