From: dplatt@coop.radagast.org   
      
   In article <7aae2352-a375-4a6a-b02d-d44bd4981236@googlegroups.com>,   
     wrote:   
   >I'm setting up a fan dipole antenna for SWL, and I need to run coaxial to my   
   desk, which is near 1) the breaker   
   >box and 2) the router and modem. What kind of cable should I buy that will   
   best shield interference. Thanks for   
   >any help!   
      
   If you want "best" shielding, it's difficult to beat the performance   
   of heliax or a similar "hardline" type of cable.  The unbroken outer   
   conductor means that the shielding efficiency is extremely good.   
      
   You won't like the price (a dollar or more per foot), it's relatively   
   stiff, and it usually requires special connectors.   
      
   A double-shielded (braid plus foil) coax will serve just about as   
   well, and will be much less expensive.  LMR195 or LMR240, or one of   
   the equivalents/knockoffs would be a reasonable choice.   
      
   If you aren't going to be transmitting, and are willing to accept a   
   small amount of mismatch at the receiver, then you could use a "quad   
   shielded" 75-ohm coax of the sort made for satellite TV feedlines.   
   This is easily available almost anywhere.  The mismatch loss (SWR of   
   1.5:1) at the junction of the 75-ohm coax and the 50-ohm receiver   
   input is unlikely to be a problem... reception on HF is often   
   dominated by atmospheric and man-made noise levels rather than by the   
   SNR of the receiver itself, and so losing a dB or two of signal at the   
   receiver won't hurt your reception.  You could use a "compression" F   
   connector to terminate the cable near the radio, and then an F-to-UHF   
   or F-to-BNC or whatever sort of adapter or pigtail you   
   require... again, the slight losses from impedance mismatch and   
   connector are unlikely to affect your listening enough to ever notice.   
      
   I suggest installing a choke balun at the antenna... a few ordinary   
   "interference suppression" ferrites snapped around the coax just below   
   the antenna will do.  This will help decouple the outside of the coax   
   from the inside, and prevents the outside of the coax from acting as   
   part of the antenna system and carrying interference from nearby   
   sources into the signal.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)