Arunas, Was it shieded FTP-5, SFTP-5 or just unshieded UTP-5 At work we measured the single pair impedance being around 100 Ohm on 10 MHz. Do you use any kind balun-transformer at the receiving end? We make video survailance equipment transmitting composite video via twisted pair up to 1 km. Planning to use this method to get signal from remote FLAGS etc. 73 Vic US5WE
Понедельник, 18 февраля 2013, 22:55 +02:00 от "Arunas LY2IJ" <[email protected]>: >>>> 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 _________________ Topband Reflector
