Hello Buck,

If I Understand you well, one wire (7 feet) runs from the buried
radials up to 7 feet high. The coax runs 7 feet above the ground to
your shack.

Whether it is possible depends on several things. For the lower bands
(where the vertical 7 feet part is short with respect to 0.25 lambda
it will work. You need to install a very good common mode (current)
balun (several ones) to avoid common mode current into your coaxial
cable. You will have a more or less floating ground.

Least common mode problems you will have when the vertical radiator
(the part above 7 feet) is about 0.5 lambda. This high impedance will
result in low current into your vertical part of you ground system.
The disadvantage is that the impedance of the radiator is high, so you
will get a very high VSWR inside your cable (losses).

In the case where the radiator is a quarter wave, you will have an
easy match, the current in the 7 feet vertical ground wire will
radiate also.

You will get problems when your 7 feet ground wire will be in the
range of 0.2..0.3 lambda. The impedance seen from the top of the
groundwire will be high, hence the voltage at the shield of your
cable. Your common mode choke will experience high voltage (with power
dissipation as a result).

When your radiator is somewhat longer then 0.5 lambda, the current in
the ground will be opposite to the current in the main radiator,
resulting in a bad radiation pattern for DX.

Is it possible for you to create some floating ground wires?

If possible, run some more wires from the 7 feet high feedpoint to
ground. When you separate them some inches, the inductance of the 7
feet wire will reduce significantly, introducing less common mode
voltage on the cable shield. This reduces the "workload" for the
common mode choke.

Hope this will help you.


Wim
PA3DJS