Dear Richard:

Oh my! It appears that you need a new reference. One may order a catalog
from the Fair-Rite site.

Your comment about the effect of ground is useful. However, the direction
of the coax run is such that it could enhance the vertically polarized (E
vector normal to the earth) wave received by the receiving antenna. This
might partially defeat the utility of a receiving antenna distant from noise
sources. I will test that hypothesis with NEC4.

73, Mac N8TT
--
J. McLaughlin; Michigan, USA
Home:
"Richard Clark" wrote in message
...
On Mon, 21 Apr 2008 10:21:36 -0400, "J. Mc Laughlin"
wrote:
Am I missing something? It seems to me that for the purpose of choking
common mode current (on the outside of the outer conductor of coax) from 3
to 25 MHz one should prefer the use of type 31. This is a receiving
application with a long run of coax.

Hi Mac,

I can't say that I have any familiarity with type 31, but certainly
the rest and others. My reference is a 13 year old hard-copy that
does not have this material listed, so it is hard to make side-by-side
comparisons for like-sized beads. Looking at the other charts it
would seem that type 31 would have less "bulk" Z (it would take more
beads at any particular frequency to equal other formulations).

As for your application, and if it is a particularly long run along
ground, or underground, ground itself may provide sufficient snubbing
of Common Mode currents. Except, of course, 60Hz which could be
particularly vicious and I would recommend running a parallel bare
ground wire to the remote ground. In that regard, you may even need
tri-ax.

73's
Richard Clark, KB7QHC