Shielded CAT5/6 is readily available. Carl KM1H
----- Original Message ----- From: "GeorgeWallner" <aa...@atlanticbb.net> To: "topband" <topband@contesting.com> Sent: Monday, May 07, 2012 9:12 PM Subject: Re: Topband: Using CAT5 in place of coax (was video baluns) > On Mon, 7 May 2012 19:17:58 -0500 > Mike Waters <mikew...@gmail.com> wrote: >>it would be interesting to >>experiment with some >> CAT5/6 sometime, just for the fun of it. :-) >> > I did that. I was testing a small dual-feed DHDL loop (-50 > dBi gain) using twisted pairs removed from a CAT 5 cable. > On the bench the twisted pair showed 100 ohm of impedance > and a loss of about 2.8 dB at 1.8 MHz on a 100' run. (I > also tried CAT 6. The results were the same. The > difference between CAT 5 and CAT 6 is that the CAT 6 > pairs' twists are more precisely controlled, which results > in a more uniform impedance and lower losses at the upper > end of the spectrum.) > > I was running two 16 foot lenghts of twisted pairs, one > from each element, into a phasing/combiner box, which had > carefully designed balanced-transformer inputs. The > twisted pairs had #31 common mode chockes every 4 foot. > While the twisted pairs worked, despite the balanced > arrangement, there was more common mode (BC and noise) > pick-up than the same runs using (non-balanced, but > grounded) RG-179 cables. The RG-179 cables had the same > #31 chokes as the twisted pairs. I attribute the > performance difference to the fact that the shields of the > coax cable were grounded, while the twisted pairs were > "floating". > > I believe that if one wants to use a balanced arrangement, > twinax may be the ultimate solution. Otherwise, just stick > with good quality RG-6. > > 73, > > George > _______________________________________________ > UR RST IS ... ... ..9 QSB QSB - hw? BK > > > ----- > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1424 / Virus Database: 2411/4983 - Release Date: 05/07/12 > _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK