Re: [IRCA] More coax experiments

[Rick Kunath <k9ao@xxxxxxxxxxx>]

Craig Healy wrote:

> One other thing I want to try is to roll out some chicken wire over the CAT5
> to see if it shields the wire from pickup.  The capacitance to ground, plus
> the inherent loss may just help.  Maybe just the 50' closest to the truck.
> It will be very easy to do an A/B test.  Set out the CAT5, do a bandscan
> with it terminated.  Then roll out 50' of chicken wire over the nearest 50'
> and do another bandscan.  Compare notes.  If it helps, then do another 50'.
> It may function just as a series of chokes on the wire itself, using the
> lossy ground for attenuation.  Chicken wire is cheap, so..


That certainly would be a very interesting test...

Did you know that you can get shielded CAT5 cable?

You need special RJ-45 connectors for the stuff because they have to 
have a grounding tab on them, but the stuff is available on reels and 
can be easily crimped to shielded RJ-45 connectors.

At least with balanced line you don't have to worry about chokes on the 
wire itself, though they still might be needed on the shield of shielded 
CAT5 or twinax.

On unshielded balanced transmission lines it's all about line balance to 
prevent common mode pickup. (Normal mode for desired signals on a 
balanced transmission line is differential mode.)

Rick Kunath
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