Esoteric question on tuner inputs and RF design

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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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