Thanks N0ywb! ?That historical insight is fascinating
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On Jan 23, 2025, at 11:31, N0YWB via groups.io <n0ywb1@...> wrote:
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Up to the mid 1970s the center pin diameter was different.
IEC 169-8 in 1978 defined interchangeability.
The diameter of the center pin in current production BNC plugs is 1.32-1.37mm (0.052-0.054¡±),
the same for both 75 ohm (MIL-STD-348B 9Feb2009), and 50 ohm (MIL-STD-348 20 April 1988).?
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I became painfully aware of the issue when I bought a compression N plug for LMR-400 at the local parts store before Field Day.?
After set-up, I measured bad SWR on my 75 meter station.?
Sweeping peaks and nulls with my antenna analyzer, and knowing the VF of LMR-400 indicated my discontinuity was at the new N connector near the antenna.
Prying on the connection suddenly made the SWR good.??
Evidently that connector had been in the store inventory a long time.?
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