[Top] [All Lists]

Re: Topband: High performance RX antenna at T6LG

To: Arunas LY2IJ <>
Subject: Re: Topband: High performance RX antenna at T6LG
From: Victor Goncharsky <>
Reply-to: Victor Goncharsky <>
Date: Tue, 19 Feb 2013 12:51:12 +0400
List-post: <">>
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" <>:
>>>> 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),
>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
>(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
>"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
>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
>the difference in price is not that great, at least in ZL.
>flooded RG6 I use, has a transmission loss of around 1.8 dB/100m.
>I hope that is useful.
>Greg, ZL3IX
>Topband Reflector

Topband Reflector
<Prev in Thread] Current Thread [Next in Thread>