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Using Coax From Old Sat. dish

Jan 28th 2012, 18:34

W1FL

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
I still have the in-ground coax leading to the mast of an old 12' sat. TV dish. There are 4 separate coax cables in this special cable set.

My question: Can I use the coax to feed a 50 ohm vertical antenna, and would there be any benefit in linking the 4 coax cables in parallel from the tuner to the antenna ?

Thanks very much, 73

Andy Knittle W1FL
Jan 28th 2012, 22:36

aa5xo

Joined: Mar 28th 2011, 02:08
Total Topics: 0
Total Posts: 0
First of all, old coax is usually bad because of water seeping into it. Check it out with a RF/SWR Analyzer such as the MFJ-269. You have to make sure the coax is good. You can measure the loss directly with the SWR Analyzer. Leave the coax open at the far end, connect the MFJ-269 to the near-end, Move the menu to coax-loss and measure at the appropriate frequency.

Secondly, connecting four coax cables in parallel reduces the input impedance to 1/4th of one cable. Maybe for a vertical, that would be a good thing. However, if the input impedance to the antenna is truly 50 ohms, feeding the antenna with 75 ohm coax is perfectly fine.

73,
Stan Kozlowitz AA5XO

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