On Monday, February 8, 2016 at 1:29:56 PM UTC-6, Dave Platt wrote:   
   > 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.   
      
   Dave,   
      
   Thanks so much for the info! Much appreciated! Is there any real advantage to   
   buying a 1:1 or a 4:1 balun as opposed to making a choke balun?   
      
   Mike   
      
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