[TowerTalk] Stub losses (was connector and switch losses)

[w8ji.tom]

Hi Chad,

> I was working on my own version of the above antenna for 80M and using
> a perfect X value (0 + j50 ohms).  Antenna looked totally kick
> butt.  Then, because I couldn't use a 1/8th wave open stub, I
> went for the 3/8ths wave open stub.  Using TLA.EXE (by N6BV),
> and using RG-8X as the transmission line, the actual impedance is,
> 
> are you ready?
> 
> 
> 5.62 + j49.69

A few dissipative ohms in the wrong place can make a big difference.
Imagine a vertical loaded with a coax stub (one popular vertical does that,
and advertises "no lossy traps"), or coax wound into a trap placed at a
critical point requiring a very high self-resonant impedance with as little
parallel R as possible!

Most of the low loss or no loss performance comes from improper modeling or
measurements.
It's easy to measure or model the wrong thing.

73 Tom




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