Tden, personally I would not worry at all about using the ~70 Ohm cable with your Icom. Even if there is a mismatch between the transmitter and the coax of a 1:1.5 SWR, that represent a reflected power of <5%. The amount of reflected power seen back at the transmitter's PA will be decreased (burn'd up) by the coax inherent Ohmic losses- and thus pose little strain on the amplifier. Modern transmitters have fail safe thermal run-away circuits to prevent their amplifier's destruction- the most you would see with a badly coupled line would be a decrease in power, as evidenced on your power output meter. At a 1:1.5 SWR you won't see a thing----- A 100 Watt transceiver can well handle 72 ohm coax without the need for any tuner.
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Something to keep in mind- 'Coax cable' is just another term for a RF wave guide.... that's where the "RG" in RG-213 (etc.) comes from. While it can be rated at a certain Ohmic impedence- it does not always exhibit that value. For instance: when a line length is in even multiples of half wave lengths, the input resistance will be equal to the load resistance- regardless of the lines impedence. Thus if you have a half wave long (but don't forget the velocity factor in calculating this length) line matching a resistive 50 Ohm antenna, it doesn't matter if the coax is 72 Ohms, it will be a "prefect match."
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That was but one of the many quirks of coax'es -- feedlines actually. I am getting a little too technical, No?... sorry
When I get like this its time for an Anecdote.
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In my lab we have ten or twelve (I forget how many) 1000 foot spools of Belden 8213 coax. Their origins predate my tenure- but that's over 2 miles of cable !- what its original purpose was to be, I haven't a clue. Anyway, its 72 Ohm, beautiful foam dielectric 1.5db loss/100 feet @100 Mhz's line.... and we have plenty of it. And because we have so much of it, my coax budget is $0- and will probably remain zero for a long time to come (ie: no general purpose 50 Ohm stuff in our future
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This cable is used for every routine RF run imaginable- and with very few exceptions, no one questions whether its to match a 50 or a 72 (or there abouts) loads. It works fine, and this spans the gamut of frequencies- from DC to ~3 Ghz, and high powers too.
Its been my experience that few antennas present a perfect "50" or "72" Ohm load. So if, say, your SWR is 1:1.5 with a 72 Ohm cable- 'tweak' the antenna with a little +/- inductance/capacitance- and "Bingo" ---- you can achieve a 1 to 1.
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Go ahead and use your 72 Ohm stuff Tden....
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......................................CF