On 16/10/15 17:07, rickman wrote:
On 10/16/2015 6:53 AM, Brian Howie wrote:
In message , rickman
writes

I've a 5 foot Octagonal loop for MF. The shield is copper water pipe,
with a gap , 7 turns inside plus a coupling winding. It does a good job
eliminating local noise (mostly ASDL hash from the phone lines)
compared
with a vertical. However the capacitance between the shield and turns
seems to load it quite a bit meaning I can't get the tuning range I'd
like.

I assume there is nothing to space the wires from the pipe other than
the insulation. Maybe you could use wire with thicker insulation? Or
if you are using straight pipe, could you use a fabricated spacer at
the corners? I guess that might be hard to assemble with soldering the
joints.

No just the insulation. It was hard enough to thread it without spacers .

I should have stuck to the original design that used plastic pipe with
aluminium foil stuck to the outside

I saw one receiving antenna made from a bicycle rim. Easy to thread. I
assume you only use this for receiving?

At an AR convention in the Netherlands ,last year , there was a 14 MHz
bicycle rim loop (aluminium) with motorised variable capacitor ,very
well made. Recently I got a bicycle rim , made of stainless steel
,hence probably not very effective as tx antenna . But the rim can also
serve as a guide for bending a copper loop .....shall try that after
testing the stainless steel rim.

Frank GM0CSZ / KN6WH