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Old 22nd April 2012, 11:07 PM   #41
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I have 10 Commercial Electric #140-857 dual florescent units in the garage and no problems receiving low-power non-profit station about 40 miles away.
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Old 31st May 2014, 12:40 PM   #42
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Bringing my thread back from the dead... I made some more impedance measurements on various receivers and tuners. The tuners were carefully tuned to the test frequency. Some vary widely when detuned, others not so much. Here are some results at 97.5 MHz:

Marantz 2230: 260 ohms, 90 deg (424 nH, Lp)
Onkyo T-15: 95 ohms, 72 deg (163 nH, Lp)
Yamaha CR-620: 130 ohms, 40 deg (330 nH, Lp)
Yamaha T-85: 100 ohms, 55 deg (200 nH, Lp)

The Marantz actually shows slightly negative losses, especially at the high end of the dial. I wonder if that's due to the adjustment of the neutralization cap that wraps back into the input of the FET?

Anyway, still not entirely grasping all the comments above, I'm wondering if the antenna and feedline impedance means much at all. I don't see any reason one couldn't use a 40, 50, 63 or 100 ohm antenna design and coax just as favorably as 75.
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Old 31st May 2014, 04:21 PM   #43
DF96 is offline DF96  England
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For typical broadcast reception the main issue is interference, not signal strength. Better quality coax, whatever its characteristic impedance, is likely to have better screening so will pick up less noise. If the antenna is already picking up up a lot of noise then better coax won't make much difference.
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