On 1/14/2012 2:23 PM, Steve W3AHL wrote:
> While PL-259's and barrel connectors may not have enough loss on HF to worry
> about, they certainly make nice markers when sweeping coax runs with a TDR!
> You can see every connector's impedance bump.
So what? The TDR is a diagnostic tool, but it is NOT an indicator of
loss. N6RK is absolutely right -- the extremely short length of line
with a small mismatch is totally insignificant below high UHF, and in
the real world, is swamped by ordinary losses in the line itself.
Remember that a connector is quite small AS A FRACTION OF A WAVELENGTH
below high UHF frequencies.
Those doing the hand-wringing about tiny mismatches ought to go back to
the woodshed to study the fundamentals of transmission lines. There's
an excellent family of curves showing the additional loss due in a line
to mismatch for various values of VSWR.
What matters a LOT more are issues like cost, mechanical robustness,
waterproofing, ease of installation, and availability. While
N-connectors have better impedance characteristics that DO matter above
1 GHz, they're also prone to the center conductor creeping out of the
Except for routers, 100% of my operation is below 1 GHz, and the only
N-connectors in my shack are on equipment or hard line they came with,
or mating with those connectors. And I make 100% of my mating
connections using Amphenol UHF to N adapters. :)
73, Jim K9YC
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