[TowerTalk] Multi-Op Station Interconnect coax type?

[Wayne Kline]

While in the midst of a inner station rebuild.   SO2R     All patch cables  Radio/BPF/AMP/6X2 and then the common ground   coax BUSS bar are made up  of
Mil-SPC-RG400   Double  silver shielded Teflon dielectric and cover. 
 
Wayne  W3EA 

 
> On Fri,12/26/2014 7:34 AM, Rich Hallman - N7TR wrote:
> > Looking to see if good quality RG213 / RG8 (95-98% shield) is ok past the amps to the high power 4O3A filters or should I use something like LMR400 / BuryFlex for those connections to keep down the potential inter-station interference?
> 
> EMC authority Henry Ott teaches that shielding provided by coax depends 
> on the resistance of the shield and its uniformity. W2VJN, author the 
> the excellent guide to Managing Interstation Interference, noted in the 
> second edition that stubs cut from coax with shield construction like 
> LMR400 deteriorated over time sitting in his garage.
> 
> My advice would be to use RG8/213-size coax with from a factory that you 
> trust for excellent construction quality and having a dense copper braid 
> and low shield resistance. Shield resistance is, of course, a function 
> of skin effect, which in turn is a function of DC resistance and the 
> o.d. of the conductor. The measured parameter for shielding 
> effectiveness is the Transfer Impedance, which is the ratio of the 
> differential voltage inside the coax to the common mode shield current. 
> The lower limit on Zt is the shield resistance.
> 
> 73, Jim K9YC
> 
> 
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