[RFI] RFI suppression cores for 147 MHz

[Cortland Richmond]

Listen to Dale; I've been to his shop (when he was still there) in Cedar 
Rapids. Interesting days.

The connector is typical of its type.  Be sure it is actually making 
contact in the shielded receptacle and that the foil shield (you won't 
find braid in a civilian product) all the way around and to a conductive 
surface of the braid; I've seen off-the-shelf cable with connectors 
assembled to the insulated side of a Mylar-aluminum shield.

FWIW department; military stuff is orders of magnitude harder to do than 
civilian. A military product I worked on a few years ago someone had 
fondly and optimistically designed with Ethernet routed on 
multi-conductor connectors (though using an otherwise well shielded 
quadraxial cable).  They were repeatedly told not to -- and not just by me.

The design had to be changed to shielded quadrax all the way down to the 
card level, and the connector to MIL-38999 with quadrax inserts  
(example: 
http://eccochicago.com/wp-content/inventory_images/Amphenol%20Quadrax%20Contacts.png 
).  Be warned.

The router is another problem.  That one is a Class A device and 
certified at an RF level three times higher than a Class B device meant 
for residential use. Reference to "for residential use" in the 
installation istructions is contradicted by the class for which it is 
certifed both in the FCC-required wording and the EN 55022 Declatation 
of COnfromity.

 From the installation instructions at
ftp://downloads.netgear.com/files/FS116_IGprt_16Dec09.pdf :

*Federal Communications Commission (FCC) Compliance Notice: Radio 
Frequency Notice*
This device complies with part 15 of the FCC Rules. Operation is subject 
to the following two conditions:
.  This device may not cause harmful interference.
.  This device must accept any interference received, including 
interference that may cause undesired operation.
Note:  This equipment has been tested and found to comply with the 
limits for a Class A digital device, pursuant to
Part 15 of the FCC Rules.  These limits are designed to provide 
reasonable protection against harmful interferences in
a residential installation....

*EN 55 022 Declaration of Conformance*
This is to certify that the NETGEAR Model ProSafe^(TM) 16 Port 10/100 
Switch with 8 Port PoE FS116P is shielded
against the generation of radio interference in accordance with the 
application of Council Directive 89/336/EEC,
Article 4a.  Conformity is declared by the application of EN35 022 Class 
A (CISPR 22).

Cortland Richmond
KA5S

On 3/2/2013 1820, Jeff Stevens wrote:
> 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.