I'll try an answer the questions in order
How "high" is your "High SWR"?
(Sound like you are mesuring this on the rig's SWR Meter, right?)
And your setup is rig->amp->external tuner->antenna, right?
SWR on tuner about 1:2 SWR on Rig 1:3 and I get a High SWR displayed on the rig with reduced power output
Yes rig, amp, tuner (even went out and double checked)
Is this happening on all bands?
What antenna are you using that makes this problem appear?
This only happens on 10 meters the antenna a Moxon Vertical cut for 10 meters. the other antenna switched from the tuner is a parallel inverted V and works fine
You are transmitting with amp on standby?
Yes the relay only closes when amp is in transmit mode, also same problem when amp OFF
I've had a similar-sounding problem with my IC-706 and had to do some grounding modifications. Your Yaesu may be picking up enough feedback in that one configuration to cause a parasitic oscillation.
I currently have a 18gauge wire independently connected from the rig amp and tuner to to a grounding bar that connects to a grounding rod in the ground. the antenna is grounded to earth but not interconnected with the grounding in the shack except for the coax
Glad to see that it wasn't just me that thought this strange
Thanks for all the Help