Topband: Coax Length

[Chortek, Robert L]

Fellow Topbanders:

The resonant frequency at my elevated vertical (5/8 wave on 30; 1/4 wave
on 80; and coil loaded for 160, mounted 3 feet off the ground, with
radials sloping up from the feed point to the roof) is about 100khz
different at the shack than when measured at the antenna.  This is not
true on 30 or 80 - only on 160.  I have not been able to figure out why
this is happening, and wondered if the length of coax could be a
contributing factor (I am not sure of the length, but think it might be
about 150 feet).

Any insight or suggestions would be appreciated.

73 de Bob/AA6VB