[50mhz] Cushcraft A50-3S Question

[George McCrary]

All,

 

This question might be too subjective to answer, but I would appreciate any
insight you may have.

 

I'm getting ready to put a used (good condition) A50-3S up at about 57 feet.
I currently have the antenna on an 8 foot mast leaning against a pine tree. 

 

I've set the antenna up for resonance at 50.0 MHz according the measurements
in the manual. When I measure the VSWR I actually get a dip at around 50.8
MHZ where the VSWR is about 1:1. The VSWR at 50.0 is almost 3:1.

 

Are the measurements in the manual that unreliable, or is the antenna being
affected by it's proximity to the tree and ground?

 

Thanks again for any suggestions.

 

George (K8QM)