The AM Forum

I have been seriously thinking of mounting a 17m rota table dipole above by TA-33. The problem is, I'll only have about 2-3 feet of separation. Any speculations of how much degradation would take place? It would be fed by a separate cable.

Modeling it would give you a good idea of what would be.  But the quick way to avoid it would be to run the 17m dipole up over the boom of the tribander to reduce coupling to beam elements.  As long as you made mental correction for azimuth direction, you'd be good to go.  I did this with a 30m dipole over a 3 element  beam and it played together just fine.

I'm not sure why you would think the tri-bander would be degraded.
Years ago I mounted a homebrew 17 meter dipole roughly about 3 feet above my tri-bander. As far as I could tell, the tri-bander never saw the 17 meter dipole since none of my settings changed in the shack after I mounted the dipole.

Put it up and check the rig, tuner, etc. settings before and after. If settings become weird, rotate the dipole so that it's parallel to the tri-bander boom.

I thought about mounting it 90 degrees out - glad to see you had the same idea.
Asked the question as I had to totally retune my 11 ele 2M yagi after it was positioned about 7 ft above the TA-33.
Thanks for both suggestions

That I can understand given the big difference in antenna frequency coverage between the two antennas. When I mounted my 7 element 6 meter beam at roughly 4 feet above the tri-bander, the lowest resonant point of the 6 meter beam shifted about 50 KHz (can't remember if it was up or down). When I mounted it roughly 8 or 9 feet above the tri-bander, the lowest resonant point shifted back to the original frequency.
Obviously, there might be some interaction given the closeness of your two antennas, but I would expect the 17 meter dipole to probably be more affected (i.e. resonant point) then the tri-bander.