Posted by
P.B. Christensen on
Jul 23, 2010; 2:59pm
URL: http://elecraft.85.s1.nabble.com/SO-239-Concerns-Another-Perspective-tp5329637p5329941.html
> 1. Many SO-239s provided as part of radio equipment are not up to the
> quality of Amphenol units. In particular, the spring fingers of the socket
> for the male pin loosen over time to the point that the connection becomes
> less than solid. This is particularly a problem if the connector is used
> repeatedly. I usually replace with Amphenol units...
I have nothing against the SO-239s used in the K3, although during assembly,
I decided to use Amphenol connectors as a substitute. I also like using
Amphenol-branded SO-239s on custom projects. The added expense for the name
is usually a small percentage of the total project cost.
> 2. The other potential problem with UHF connectors, in my opinion, is the
> integrity of the shield connectivity through the connected pair. If the
> backshell loosens, there is no longer a solid connection either at the
> toothed parallel portion, nor through the backshell.
And that's my objection to the UHF connector combination. For example, I
gained 0.75 dB in the shack on 10m simply by re-tightening a series of
connectors that seemed hand-tight. After installing some new equipment, I
decided to conduct a loss budget analysis from the transceivers to the shack
antenna output ports and all points in between. I was seeing too much loss
through the system.
When I used slip-joint pliers and ensured that the teeth of all '259s mated
with the '239s, measured shack losses were minimized. I have a lot of
switching here and with switching, there are many UHF connectors.
Electrically, the sole conduction mechanism of the PL-259 is the inner
surface of the threaded shell and to Joel's point, the threaded shell is
only press-fitted against the connector body. A low-loss connection path is
wholly dependant on the force of the shell to the body and the shell against
the 239 threads. It's a miracle the UHF connector works at all.
Paul, W9AC
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