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Topband: Coax for Rx Sites

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Subject: Topband: Coax for Rx Sites
From: Greg-zl3ix <>
Date: Tue, 30 Nov 2010 11:02:06 +1300
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Hi all,

Ever since I first commissioned my remote receiving site in 2004, I have
had issues with coax.  At that stage, as I needed over 400m, I went for the
cheapest 75 ohm that I could find, namely RG59.  I have found, as usual,
that you get what you pay for, and I have probably replaced it all at least
3 times over the years.  The problem is that the RG59 has an aluminium
braid, and this deteriorates over time, even when protected from the
weather.  Even when new, the insertion loss on TB is not that great at abt
1.7 dB per 100 ft.  After a couple of years of use, the loss starts
climbing until the cable run becomes unusable.

Another problem is that I pass DC down the coax to power relays in switch
boxes etc.  I find that when the screen starts to deteriorate, the DC
causes micro arcing, and severely raises the noise level, to the point
where the antenna becomes unusable.

I have seen many references to CATV cable being used for long Rx antenna
runs.  Can someone, who has experience of long runs of 75 ohm cable, give
me some example part numbers from Belden, or other manufacturers, please. 
I am not confident of being able to obtain decent cable at an affordable
price in ZL, but at least if I have some part numbers I can make enquiries.

Thanks + 73,
Greg ZL3IX
UR RST IS ... ... ..9 QSB QSB - hw? BK

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