[TowerTalk] Symptoms of antenna interaction?

[Al Kozakiewicz]

Still have a foot of snow on the ground, so I'm not quite ready to climb yet.

See photos on QRZ page.

I have 3 antennas on a 10' mast sticking a total of 8' out the top of the tower. From top to bottom, 2M7, 6M3 and a C3, all equally spaced.  All were tuned to resonance on the ground.

Now up in the air, the C3 and 2M7 are fine, but the 6M3 is useless. The SWR is about 3:1 and Z=~70 ohms at the minimum for both.

Is this symptomatic of interaction, i.e. feed point characteristics change while resonance frequency remains the same? If so, what is a recommended solution? The one possibility I haven't checked yet as it requires climbing is a bad rotor loop cable.

Al
AB2ZY