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[AMPS] coax connector ratings

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Subject: [AMPS] coax connector ratings
From: (Jon Ogden)
Date: Fri, 28 Sep 2001 07:15:25 -0500
on 9/28/01 3:45 AM, Steve Thompson at wrote:

> The Suhner catalogue gives a graph.
> 20MHz  5000W
> 50MHz  3200
> 200MHz  1600
> 1000MHz  750
> 10000MHz 250

Yikes!  750 Watts into an N at 1 GHz.  That's pushing it.  In the cellular
industry the typical max power that is usually talked about for N connectors
is 500 Watts at 900 MHz.  Of course, the H&S figure is into a good load.

Of course the original question was the ratings at HF.  At amateur power
levels, there is absolutely zero problems with either the N or the UHF.  I
would believe the UHF would handle more power because of the large diameter
center pin (of course the quality of UHF connectors does vary and I would
assume a UHF with a phenolic dielectric to handle much less power than a UHF
with a Teflon dielectric).

IMHO, there is really not much advantage to using N connectors at HF.  The
performance improvement in terms of VSWR and S21 are so minimal as to be
negligible.  N connectors are more expensive and harder to assemble.  They
do have the advantage of being more waterproof than UHF connectors in
outdoor environments but other than that a UHF is really a better connector.
I would recommend N connectors at 2 meters and above but even at 2m, the UHF
is still pretty good.  But as the above chart shows, above 200 MHz, legal
limit ham amps become a problem for N connectors.

A lot of people think that because of their size that N's are inherently
high power connectors.  Well, in reality the male/female interface of an N
is really identical to that of a BNC connector.  Yep, center contacts are
the same size.  The difference is in the outer conductor and contacts.  If
you doubt be try mating a male N to a female BNC.  You can do it and the fit
is pretty good.  The geometry of the N's do make their voltage breakdown a
bit higher than the BNC but not that much.

If you really want high power handling, go with a 7/16 DIN.  Overkill at HF
for sure though!



Jon Ogden
NA9D (ex: KE9NA)


"A life lived in fear is a life half lived."

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