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...all out of bubble gum
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Discussion Starter #1
I'm considering a CB base station for my BOL. I was wondering if the length of cable from the unit to the antenna has much bearing on power consumption as far as receiving and transmitting.

If I decide to put my antenna on a hill 300-500 feet from my BOL, is there anything special about power that I should know?

Thanks in advance!
 

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The issue with feedline length is loss at a given frequency.

Running the numbers for 27 Mhz and 500 ft Belden 9913 feedline, you have pretty significant loss, 3.22db, which is half of your power... so your 5 watts looks more like 2.38w actually making the antenna.. This assumes your SWR is 1:1...Higher and the losses increase exponentially.

My advice is put the antenna near the shack and call it done. Amplifiers wont help here because at these freq's, it will impact receive as well...

You can do your own calculations with an applet at http://www.arrg.us/pages/Loss-Calc.htm

Good Luck!

73,
MO-GO
 

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...all out of bubble gum
Joined
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871 Posts
Discussion Starter #3
The issue with feedline length is loss at a given frequency.

Running the numbers for 27 Mhz and 500 ft Belden 9913 feedline, you have pretty significant loss, 3.22db, which is half of your power... so your 5 watts looks more like 2.38w actually making the antenna.. This assumes your SWR is 1:1...Higher and the losses increase exponentially.

My advice is put the antenna near the shack and call it done. Amplifiers wont help here because at these freq's, it will impact receive as well...

You can do your own calculations with an applet at http://www.arrg.us/pages/Loss-Calc.htm

Good Luck!

73,
MO-GO
Thanks for that! It was exactly what I was looking for!
 
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