[TowerTalk] connectors

[Michael Tope]

I saw some more evidence yesterday that this N stuff
is pure marketing hype. My friend Warren and I took
apart a non-working Henry 2006 amplifier (6 meter x
3CX800A7) yesterday. While the output connector on
the 2006 was a type N, when we took the amplifier
apart, we found that the output signal was routed
thru a bandpass filter module. Both ends of this
filter were fitted with UHF connectors, suggesting
that electrical performance wasn't the driving factor
in selecting the type N output connector. BTW, our
clubs FT-847 which is driving this amp uses a slighly
more sensible approach. The HF, 6M, and 2M ouput
connectors are all UHF. Only the 70 cm output
connector is type N.

Mike, W4EF..............


Michael C. Tope, W4EF

email: W4EF@pacbell.net
  web: www.dellroy.com

----- Original Message -----
From: "Tom Rauch" <w8ji@contesting.com>
To: <towertalk@contesting.com>; "Bryan Fields" <kb9mci@qsl.net>
Sent: Sunday, July 30, 2000 4:44 AM
Subject: Re: [TowerTalk] connectors


>
> > I think that a N is THE BEST connector to use. The two gaskets give it
> > water resistance that no PL-259 can match.  After years of being outside
> > unprotected the silver may have .006 of a inch of sulfide (i have
actually
> > mesured this amount!) on it but the inside will be nice and shiny.
>
> It is more water resistant.
>
> > Secondly you do not need to heat the whole connector like you have to do
> > with a pl-259, this means no melted coax and no impedance bumps b/c of
> > melted dielectric. (i can never put a pl-259 on right the first time,
the
> > coax always melts!)
>
> That's a non-problem if you solder with a big enough iron and pre-
> tin, and if you use a good connector.
>
> On the other hand, the N depends on grabbing the braid with only a
> mechanical connection to prevent pulling out. The gaskets "sort-of"
> squeeze the jacket, but have no holding power.
>
> If the cable has a loose braid, or a flexible jacket, the center pin of
> the N will move all around when you pull on the cable.
> Mechanically, they are poor connectors for gripping the cable
> although they hold all right with thick braid hard jacket cables.
>
> My biggest gripe is they are low power connectors. They have the
> same approximate pin size and air gap as a BNC connector. Not
> exactly high-power construction.
>
> The SWR bump in a PL-259-SO-239 pair is in the 1/2 inch of area
> in the SO-239, where the impedance is about 35 ohms or so. 1/2
> inch of such a small bump causes almost no change in the system
>  below a few hundred MHz.
>
>
> >Third, the connector is less noisy b/c the the
> > center pin is under pressure from the connector.  This is very important
> > in repeater installations, especially in the duplexer. Many a crackling
> > noise has been traced to a bad uhf connector on a duplexer.
>
> At one time I was responsible for about 30 VHF repeaters. I never
> saw that problem even one time. Factually, the UHF connector
> makes a much better connection than the type "N". Both surface
> area and pressure are higher in the UHF connector.
>
> Now I don't object to "N"s where they are needed, like on SWR
> critical upper VHF and UHF systems where power levels are low.
> But when I get hardline with N fittings I machine them into good old
> UHF style fittings by boring out the center hole and shortening the
> threaded area a bit. I then gut a SO-239 and use a brass tube to
> solder the center pin to the feedline.
>
> None of those hard-to-assemble easy-to-pull-apart low-power N
> connectors in this fellows station!
>
>
> 73, Tom W8JI
> w8ji@contesting.com
>
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