[Top] [All Lists]

Re: [TowerTalk] PL259 Insertion Loss?

Subject: Re: [TowerTalk] PL259 Insertion Loss?
From: Jim Brown <>
Date: Sat, 14 Jan 2012 14:54:19 -0800
List-post: <">>
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

TowerTalk mailing list

<Prev in Thread] Current Thread [Next in Thread>