On 8/23/2010 2:53 PM, Peter O. Brackett wrote:
Roy:

Thanks for your input on the effects of interference from other
transmitters, especially BC transmitters, point well taken.

I suppose one might add some kind of carefully designed passive
filtering to the devices to 'notch' out offending BC stations, etc...

But... that would be messy and complicated.
. . .

Yes, it is. I've done it, but a lot of care has to be taken that the
filter doesn't have a significant effect on the impedance being
measured. At best, it usually also restricts you to a relatively narrow
bandwidth. It might be adequate for your particular purpose, however.
But for the job you describe of evaluating a radial system, a simple
homebrew resistance bridge is perfectly adequate. _Solid State Design
for the Radio Amateur_ had some examples, and I assume its successor
_Experimental Methods in RF Design_ does also.

Roy Lewallen, W7EL