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Author Topic: Feed Line Loss - Reciprocal?  (Read 356 times)
K8QLW
Member

Posts: 37




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« on: September 05, 2009, 11:40:35 AM »

I was checking coax feed line loss for 30M using http://ocarc.ca/coax.htm.

Just to keep it simple I plugged in the power as 100 watts and the SWR as 1:1 and the cable length as 100 feet.

Tandy RG-58 showed a loss of 24 watts (24%) while Beldon RG-8 showed a loss of 12.009 watts or about 12% for the same length.

Question:  Are those losses reciprocal?  In other words would a received signal be attenuated by the same percentage?  Always wondered about that.

Thanks,
Kent (K8QLW)

(Posted in Tower Talk and QRP Forums also)
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N7FE
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Posts: 24




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« Reply #1 on: September 05, 2009, 02:15:27 PM »

Never heard of a line that had loss in only one direction. So, yes, any loss experienced will happen on both transmit and receive.
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N0UY
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Posts: 158




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« Reply #2 on: September 06, 2009, 04:25:31 AM »

Kent,
As stated, the loss is evident in both directions.  I was fortunate in my younger days to do a considerable amount of tower work for a local commercial two-way radio shop.  Many times the cable was being replaced during the job so I had access to much of the take down cable for my wages.  Thus I have 7/8" hard line running to most of my antennas which are all more than 200 feet from the shack. 1.8 Mhz thru 432 Mhz.  Atenuation has never been my problem.  Bottom line,  use the best cable your budget can afford.

Best from Minnesota,
Ray
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K8QLW
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Posts: 37




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« Reply #3 on: September 07, 2009, 01:22:42 PM »

Thanks much gentlemen for the input. (No Pun)

kent
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