Common mode chokes (CMC) work best if the coax shield is grounded with a
low impedance ground (very short) at the point it enters your dwelling.
A good lightning arrestor like an ICE that will shunt EMPs and bleed off
static build up work very well. Then you place the CMC after the ground
point so that the currents blocked by the choke have a low impedance
path to ground. I use a second one at the rig to catch any stray currents.
I have never tested the effectiveness of either Radio Works or W2DU's
products so I can't really comment on those. But I do suggest you take
a look at this article by W1HIS
http://www.yccc.org/Articles/W1HIS/CommonModeChokesW1HIS2006Apr06.pdf
If you do not have a good RF ground in the shack (short and low
impedance), then focus on grounding the radio and the PC together and
don't worry too much about having then bounded to an actual ground point.
This is the best article on shack grounding I have ever seen for
explaining how to set up a RF ground system properly and why ground
loops are bad and why most RF ground's are actually very poor RF grounds.
Tim Ellison
On 12/22/2012 5:15 PM, Robert Costa wrote:
All,
As you may have seen from previous posts, that I have RF ingress issues on my Flex 5000a restricting my use of the flex to 40 meters and below. As I want to start addressing these issues, I would like to know what products others have used.
I need to eliminate common mode currents at the feedpoint of my 80-10 meter dipole. I have seen Radio Works line isolators, but have been told that they are not very effective. I have been told to use a W2DU current UNUN from a company like the wireman.
I am open to suggestions as I do not want this to be an extended engineering science fair.
As this RF ingress issue has been a complete irritating experience with my Flex, I would like to hear who has used what and what the results and over all costs have been.
Thank you,
Robert
KB6QXM
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_______________________________________________
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[email protected]
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This is the FlexRadio Systems e-mail Reflector called FlexEdge. It is used for
posting topics related to SDR software innovation and other technical SDR
topics.
