First. Thanks so much for the lessons in this thread.
I got my SWR lowered for all my antennas:
CR8900 (quad band): 1.2-1.4 across all bands
- previously at about 1.7 on 2m/440 and sky high on 6m/10m
SG7900 (big dual band): 1.1
diamond 'slimgainer' (not sure the PN, but it's a dual band): 1.7-1.8
Here's what I did...
drilled a hole in the Gamiviti rack, installed the UHF mount and tested the antennas. it was that grounding isssue - I previously had just a wire, no braid. so attaching to the rack did the trick!!