I did some tests a few years ago on unshielded CAT6 (UTP) cable. The twisted pairs in the cable are rated at 100 ohm nominal impedance, so I paralleled two sets of twisted pairs together and measured their VSWR. Surprisinlgy I found the cable handled 100W at 20m, with negligible VSWR. I thought about using the CAT6 for the feedline of portable antennas, but found that the noise pickup was very high. To do this properly (which I didn't do in my esperiement) one would use a simple 1:2 unbalanced-to-balanced balun for a single twisted pair, as well as STP cable, but I don't see any problems doing so. 73, Jim W8ZR
> -----Original Message----- > From: Topband [mailto:[email protected]] On Behalf Of PA3CSG > Sent: Saturday, January 02, 2016 09:53 AM > To: [email protected] > Subject: Re: Topband: Using shielded CAT5 data cable as feedline for active antenna; > benefits of multi-turn K9AY loop/SAL/etc? > > Hi! > > I tried to measure this UTP cable as a receive line. For the results see: > > http://pa3csg.hoeplakee.nl/joomla25/index.php/rf-construction/115-0-10-mhz-r eceive-over- > utp > > The plan is only slowly moving forward: > > To use one twisted pair as a receive line > One pair as the supply voltage > One pair to communicate via a RS485 protocol to control a several RX > antennas / K9AY and to control the gain of the preamp as well. > One pair left. > > Since the discussion is going this way, how about the above idea? > > I have not tried it but would be interested in your comments. > > Regards & HNY! > > Geert PA3CSG > > > > Op 02-01-16 om 16:45 schreef Pete Smith N4ZR: > > I was recently reading a web page by LZ1AQ > > <http://www.lz1aq.signacor.com/>. It is full of fascinating data and > > design equations for the use of small magnetic loop antennas. There > > were two points, in particular, that caught my layman's attention: > > > > 1. He recommends using shielded CAT5 data cable with RJ-45 connectors > > as feedline. The obvious advantage is having three pairs left over > > for voltage supply and control. See > > <http://active-antenna.eu/amplifier-kit/> for more information. > > > > 2. He cites experimental data showing that coplanar crossed loops and > > multi-turn quad loops both offer very significant improvement in the > > recovered signalcompared with a single loop. See > > <http://www.lz1aq.signacor.com/docs/experimental-comparison-v10.pdf> > > to check whether I got this right. Anyway, it occurred to me to ask if > > anyone has ever tried multiturn K9AY, SAL or flag/pennant receiving > > antennas, and did you see something similar? > > > > Any other critiques of his design would be appreciated. The price is > > certainly right, and the construction looks good. A couple of 1-meter > > coplanar loops wouldn't be at all hard to construct. > > > > _________________ > Topband Reflector Archives - http://www.contesting.com/_topband _________________ Topband Reflector Archives - http://www.contesting.com/_topband
