Shielded CAT5/6 is readily available.
Carl
KM1H
----- Original Message -----
From: "GeorgeWallner" <aa7jv@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 <mikewate@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
|