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Got a great answer from someone who perhaps preferred to be anonymous:
There is no problem coiling up excess coax. As long as you don't coil it too tight. There is a 6" minimum bend radius for RG-8 size cable. The inductance thing is something someone got garbled. Coiling it up will create inductance for signals flowing on the outside of the coax. This is called a choke balun and is commonly used at the feed point of the antenna. It has no effect, other than the length of the cable adds a little loss, to the desired signal that is flowing on the inside of the cable. Remember in coax the desired signal flows between the inside of the shield braid and center conductor. Any signal flowing on the outside of the coax has no use and may be undesirable. This is why you can tape coax to masts and bury it underground with no effect on the signal. On 80m there is not always a reason to cut the cable just long enough to reach, but on VHF/UHF excess length just means more loss in the coax and is not desirable. Also if you have a lot of extra coax coiled up and you are using a tuner to say make the 80m dipole work on 30m the extra length could cost you something. For example I use my 160/80/40/30 dipole array on 60m (5MHz) band. The Z of the antenna is something like 388-j1200ohms. This high SWR increases the loss in my coax by allot on 60m. In fact the loss is 7.5db. This means my 100 watt is reduced to 18 watts at the antenna. If my feed line was shorter the loss would be less of course. So in this case if I had a lot of extra feed line, short[en!]ing it could really improve my signal strength. |
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