[TowerTalk] Stacked TH-11 and 40-2CD Spacing and Interactions?

[Ron Majewski]

Hello to all,

I am currently pondering an antenna stack starting with 
a HyGain TH-11 with a Cushcraft 40-2CD about 8ft above it.  
Is this nominally enough space between the antennas?

I remember hearing somewhere (the infamous "somewhere") that the 
40-2CD has a secondary resonance around 18 MHz.  Can anyone verify this?  
If this is true, am I setting myself up for an interaction problem when 
I use the TH-11 on the 17m band?  

I would appreciate any insight or experience you can share with me.

Thank you and 73,

Ron (W8RU)
majewski@erim.org

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