[RFI] RFI suppression cores for 147 MHz

[Jeff Stevens]

Thanks to everyone who has contributed to the discussion on the use of
shielded twisted pair.  I'm interested in what folks think about connection
of the following devices in regard to providing a circumferential shield.
They are a fairly good representation of what is easily available 'off the
shelf' (and at reasonable cost) to the home user.  I've not used either of
these two exact products -- simply similarly constructed products.  My
belief has been that they provide what is effectively a circumferential
shield.  Sure, there are actually some small gaps but the connection is
certainly low impedance (I've proven so at DC anyway) and the gaps are
small relative to VHF wavelengths so I've understood them to be
inconsequential.

First, the shielded RJ-45 connector:
http://sewelldirect.com/Cat6-Shielded-RJ45-Connectors-Stranded-50pc.asp?gclid=CMKYjtSO37UCFUZa4AodLUoAHA

This is assembled and crimped exactly like an unshielded connector with the
addition of insuring the STP foil shield and drain wire are in contact with
the metal shield (which extends around the base of the connector and covers
much (but not all) of the interior.

Second is the networking device:
http://www.amazon.com/Netgear-ProSafe-16-Port-Ethernet-Desktop/dp/B000063UZW

The above device has ports with metal tabs on the sides which make contact
with the shielded jack.  Again, this provides a partial (but not complete)
shield where the plug meets the jack.  Note that the entire port is metal
shielded as well.  The metal chassis comes with an terminal on the rear
intended for earthing.

In both the case of the RJ-45 connector and ports on the device above, I've
understood the very small gaps to be inconsequential.  Does anybody have
any thoughts?

-Jeff
W7WWA