In message , rickman
writes

The capacitance of the loop to the screen meant that at the minimum
variable C setting ,I couldn't get the maximum frequency of about
500KHz I wanted, so I had to take turns off. I now need more parallel C
to tune the look down to 136KHz.

Wow, that loop must have a *lot* of capacitance. Is there a way to
space the conductors away from the copper tubing in the run?

Not easy

I'm curious why you would use copper pipe for the shield. Because it
provides both shield and support? I guess there are a million ways to
build a shielded loop. I like the idea of using coax, but I don't know
if that also has serious limitations from the capacitance between loop
conductor and shield.


It seemed a good idea at the time. The original design used plastic pipe
covered with tin-foil ,but I wanted something that would survive a
Scottish winter outdoors.

PVC 4-7 Loop Antenna Al Burzynski KA5JGV ( it's on the NDB yahoo group)

it used 12 turns. I think the use of plastic pipe and external tinfoil
reduces the C.

My loop does work quite well, and has survived outdoors but I think it
could be improved

Brian



--
Brian Howie