[Lowfer] Isolation Transformers

[John Andrews]

Peter,

> He also employed loop feeders of coax grounded at the rx end. I think
> John Andrews and possibly others on the LowFER net described this
> technique.
> So then the question: If using Lyle's balanced rx-loop approach which
> allows loop-located grounding at the center, should the coax feeder/s be
> ground connected at the loop, the rx, or both [I think not the latter,
> but... .] ?

I'm currently ducking the issue of grounds altogether. Given that my loops
are very small targets under very tall trees, so far, so good. My present
setup has the loop series-tuned into a 10-turn winding on a toroidal core.
No ground at all on the loop side. A 20 turn winding on the opposite side of
the core runs back to the shack. I am treating that as a balanced line at
this point.

Up at my Maine location, I am using a twisted-pair microphone cable for the
shack-to-loop connection. At home, I've still got RG-58. In both cases,
there is no ground connection at either end, just transformer windings. I
did some tests up in Maine comparing the mike cable and the RG-58, and found
little difference. The old audio guy in me says that balanced, twisted pair
is better. Cat 5 computer cable would be excellent. I don't think that
shielding of the cable would offer any real improvement. The mike cable in
Maine has a good shield, but I get more noise if I try to connect it to
"ground" at either end. If the cable were running parallel to a lot of other
electrically active stuff, that might not be the case, though.

John Andrews