>>> The key component here was the CAT 5 single twisted pair to feed the flag antenna without any common mode noise pickup (it is necessary to strip the CAT5 and separate each of the 4 pairs), >>>
Hi, Yes, T6LG hears really well. I just wondering what is the reason to separate each of CAT5 pairs? Why not use original outdoor CAT5(e) UV protected cable with other 3 pairs floated (or might be loaded with 100 ohms resistors from both ends for I don't know what reason). I used single ordinary CAT6 cable (200 m meters long) to feed 2 pairs of temporary reversable Beverages in IARU HF in 2011 (LY0HQ - 160 station)- every of 4 directions via own pair in same not splitted cable. Terminated near radio, transformers adjusted to 100 Ohm line. Everything worked fine, I just forgot that cable in field after removing temp installations - cows chewed it till I found it in autumn. "Worked fine" is not very scientific evalutation, but Greg ZL3IX helped to decide with something real - Thank you Greg. See his message with measurements below. CAT6 is better variation of CAT5, so I had less loss and better crasstalk. 73 Arunas LY2IJ : >>Hi Arunas, I have just run a test on a 200m length of cat5 cable. I bought a 305m reel for controlling the relays at my remote receiving site, and only needed 100 m of that. I tested the cable using my N2PK VNA with the MyVNA software. I took the precaution of using a balun at each end of the cable, as the cat5 pairs are balanced feeder, while the VNA is single-ended. I checked the transmission impedance before I started, and found it to be 100 ohms, as expected, so I connected two lots of two pairs in parallel, to make two 50 ohm balanced lines. The results are :- transmission loss 7.5 dB at 1.8 MHz, or just under 4 dB/100m. Crosstalk -45 dB between the two lines. For a 100m length you could therefore expect the crosstalk to be around 50 dB down. Thus it seems that cat5 is a fair alternative to coax, although, as I said before, the difference in price is not that great, at least in ZL. The flooded RG6 I use, has a transmission loss of around 1.8 dB/100m. I hope that is useful. 73, Greg, ZL3IX _________________ Topband Reflector
