Hi Mario,
Most of these reasons for N connectors not being on ham gear don't
seem relevant anymore. Unfortunately, it appears that most hams(?)
buy premade cables with connectors on them....
However, I wonder which is worse a poorly made N connector or a poorly
made UHF connector? There are more ways to mess up making an N
connector...
You haven't acknowledged the problems of the center pin of the N
connector migrating back into the connector via hot/cold and
mechanical cycling of the center dielectric. Lots of reports of N
connectors failing this way. I would guess fractionally as many N
connectors fail this way as UHF connector failing via the center pin
problems you describe.
I guess I am still not sold on the size of the type N connector center
pin being large enough. I guess I still believe in large surface area
being important because of the skin effect. There simply isn't much
contact area. Just because you can run 6KW for 20 minutes in a lab
condition with a freshly made connector does not imply that one wants
to do so in adverse field conditions.
You also haven't discussed cost. I figured out that in the past 40
years I have made up over 1000 UHF connectors. My guess is that the
same thing with N connectors would have cost me another $2K or more.
I'd rather spend my money elsewhere. I really don't think the extra
money would have bought me anything in performance, reliablity or
anything measurable. (HF only here)
By the way the total number of connector failures I've experienced is
probably under 10. I consider this to be quite acceptable. Half were
due to UHF connectors manufactured with out of spec center pin sizes.
73 de Brian/K3KO
"i4jmy@iol.it" wrote:
>
> Hi Chris,
>
> You don't frequently find N connectors on amateur transceivers,
> amplifiers and antennas because they are expensiver than UHF type and
> mainly because a large number of HAMs doesn't want to learn how to
> install them. Knowing this situation, it would be a double mistake to
> use N connectors, at least from the manufacturer perspective.
> Most of professional equipment stopped with UHF during the late 70' and
> you can find HF transmitters antennas and amplifiers with N connector
> rated for RF power well exceeding the Kilowatt.
> The bigger size of the UHF central pin connector lead to believe that a
> UHF connector withstand more current than N but this is true only at DC
> or in the lowest HAM band where mechanical precision is a less
> stringent matter.
> Not counting that even a small tin excess in the edge of an UHF central
> pin of male often causes to open the fingers of UHF inner receptacle
> thus further reducing quality and quantity of the contact.
> Another gap with UHF is that outer parts of male and female should be
> perfectly planar and pressed to insure a good contact(as it is in EIA
> connectors) meanwhile the typical rough construction and expecially the
> screwing of the outside ring of UHF doesn't insure it. The outer ring
> often looses, expecially outside where hot and cold themperature cause
> a number of thermal cycles most days of the year. It's just proper to
> point out that optimal weatherproofing an UHF connector that inherently
> is not, doesn't prevent outer ring losening because of thermal cycles.
> Another weak point with UHF is that cable is not pressed inside
> connector and if through shield or even the inner some umidity migrates
> because of capillarity effect, also passes into connector and contacts.
> It's not uncommon to remove a self amalgamating tape from an UHF
> connectors joint, finding out a perfect bright outer surface and then
> to discover oxidization inside.
> Concerning N power rating, the connector it's perfectly useable at
> 800/1000 W with any reasonable SWR at 150 MHz and above.
> Using FM broadcast equipment I personally made a test using N
> connectors and 6 KW at 100 MHz on a dummy load. After 20 minutes the
> connector was quite warm but much colder than the teflon cable used and
> there was no failure or irreversible damages.
> It's evident that reducing the forward power to 1.5 Kw and the
> frequency below 30 MHz there is no kind of problem with RF currents,
> direct or reflected and using N connectors and problems of other nature
> are also avoided.
>
> 73,
> Mauri I4JMY
>
>
>
> > ---------- Initial message -----------
> >
> > From : owner-towertalk@contesting.com
> > To : <towertalk@contesting.com>
> > Cc :
> > Date : Mon, 2 Apr 2001 10:30:31 +0200
> > Subject : [TowerTalk] Connectors
> >
> > After many years of struggling with soldering into little holes on
> lousy
> > connectors, I gradually started migrating to N connectors. They are
> less
> > lossy, generally waterproof and mate more reliably than UHF
> connectors.
> > Unfortunately, ham equipment suppliers continue to churn out high-
> power
> > equipment with UHF connectors, for reasons that I cannot understand.
> >
> > However, the reason for this message: I recently (a year ago) took
> the
> > plunge and invested in a crimping tool. I should have done it two
> decades
> > ago! The connectors take a lot less time, are more reliable and look
> > better. I can generally install a UHF or N connector, male or
> female, in
> > under four minutes on RG213-type cable; even when dangling from the
> tower.
> >
> > The connectors are priced similarly to solder-on types and are freely
> > available from professional communications sources in this country.
> I can
> > only imagine they must be similarly easy to find in Merica.
> >
> > If you really insist on soldering connectors, you absolutely must
> invest in
> > a Portasol butane-powered soldering iron. It produces about 175 W of
> heat,
> > enough to solder any connector (at least ones that amateurs would
> use). I
> > have not found another torch in the same league. It is sufficiently
> > powerful to heat the casing if required, so that you can get good
> flow and
> > good mating with the braid.
> >
> >
> > Chris R. Burger
> > ZS6EZ
> >
> >
> >
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