[TowerTalk] Connector insertion loss

[Rod Fitz-Randolph]

>If you are going to splice your cable don't use pl259's. Use N-type
>connectors. Pl259's are lossy and they have a bad impeadence bump.
>They are really 75 ohm connectors. I have several splices (using N-type
>connectors) in my cables. Checked them all with a sig gen and a spectrum
>analyzer. They all have less than .3 dB insertion loss.
>
>N connectors are weather proof, and have very low loss. I have no idea
>why everyone uses pl259's, they are the worst connector I can think of,
>except maybe RCA's.
>
>73 de Martin - N3HRT
_________________________________________________________________________
I respectfully disagree to this extent:

   I, and others before me, have had trouble with N connectors in that the
center conductor of the N connector is soldered to (and therefore
physically connected to) the center conductor of the coax.  Unfortunately,
the cold can sometimes cause the center conductor to contract more than
the outer conductor (coax) and causes the pin to retract and sometimes
pull away from the female connector's center conductor.  It's rather
obvious the results: no continuity.  I've had this happen to me.  It is
better, when using N type connectors, to solder the center conductor a
little further out than is usual in order to keep this from happening.

I might add that the longer the coax run, the greater the possibility of
that happening.  A short run might not have sufficient temperature
coefficient of contraction to cause this.  (I may not have used the
exactly correct terms to describe this phenomena but I hope you are able
to follow the gist).

On the other hand, UHF style connectors normally do not have this problem.
It is my opinion that at HF frequencies, UHF connectors don't cause enough
discontinuity of impedance to a feedline such that you could ever measure
the effect, even with a sensitive, expanded-scale wattmeter.
__________________________________________________________________________
>"...they are the worst connector I can think of, except maybe RCA's.
__________________________________________________________________________
That statement requires some justification or explanation. "They are the
worst connector I can think of"... for what?  HF frequencies?  Don't
think so.  Worst in what way?  SWR?  Leakage? Moisture?  What?

Anyhooooo,  that's my two cents worth: light up your flame throwers.

Rod, H5HV
w5hvv@aeneas.net





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