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Re: N-connector loss



Al,

With the usual caveat "your results can vary", yes I think you can expect
N-connectors to be very repeatable in performance if you follow the
manufacturers assembly instructions.  On of the big advantages of N-types
with their low loss is their good impedance match...this is where the "old
UHF" [PL-259, SO-239] connectors really fail.  In my opinion [not humble
;-)], UHF are junk above 150 MHz.  On the job I do not use them except
where they connect to the radio connector.  I can measure down to 0.1 dB
loss and have never measured more than that for a new N-connector!

Now there is no reason to make up these connectors out on the ladder in the
breeze.  Figure out your cable run and  make up the antenna end on the
bench, in advance.  The hardest part of assembly is soldering the coax pin.
 Use a small solder iron tip with about 50w iron, min.  Wipe the wire and
pin with alchohol before soldering [this removes oils from handling that
interfers with solder flow.  Fresh tin the iron tip and preheat the pin for
about 20 second and apply a little solder, wait, a little more solder,
again.  If you do this you will see the solder flow into the little hole in
the pin very neatly...and if you nerves are steady, you may not have any
excess sloder on the outside of the pin.  Another trick is flaring out the
braid over the shield ring.  Use a small wire brush [looks like a big tooth
brush] and comb out the braid so it is not woven, push into the groove of
the ring and cut the excess flush with the ring edge.  The connector will
go together very neatly.  All this is hard to explain in words but is shown
in the ARRL antenna handbook, I believe.  PS: always use an ohm meter to
check for good continuity and for shorts after putting on each connector;
saves grief later if you get it installed and find high SWR due a mistake
in assembly.  Be sure to properly tape and seal your outside connectors!
Then its good operating from that point on.

Finally, the only place that this loss is critical is before the first
preamp.  The gain of the the preamp and convertor will make any connector
loss insignificant down stream.  However, one should minimize the number of
connectors in the line [try to use one continous run over several short
pieces stuck together].

Ed

>From: Al Lawler <alawler@us.oracle.com>
>  I've been following this discussion with some 
>interest, since my final configuration is going to
>involve some pretty long feedline runs (and a few
>n-connectors along the way.)
>
>  I'm assuming the .15db/pair number is for a 
>perfectly installed connector done by a professional.
>
>  Does anybody have any feel for how different the
>performance is for connectors installed by the 
>average joe-ham with a soldering iron and 2 thumbs
>standing on a ladder at night during mosquito season? :^)
>
>
>If I install my own (assuming it's not shorted),
>can I assume I can get an equivalent level of
>performance?
>
>  -al
>  WB1BQE
>
>
>Jerry Pixton wrote:
>> 
>> Pieter,
>> 
>> Thanks for the reference. I guess my number of 0.25 per pair on N
>> connectors is not too bad. But it is certainly different than 0 dB loss
>> ahead of the first all important low noise high gain preamp.
>> 
>> Jerry, W6IHG  just waiting for my antenna to arrive so I can get hands-on
>> with the S-band downlink.
>> 
>> At 02:48 PM 5/20/01 -0400, Pieter Ibelings wrote:
>> >Please look at page 2 of this file at the Amphenol web site:
>> >
>> >http://www.amphenolrf.com/pdf/type_n_spec.pdf
>> >
>> >They spec the loss as 0.15 dB loss at 10 GHz. I doubt that amphenol is
going
>> >to publish incorrect specs. Those specs are consistent with my
measurements.
>> >
>> >Pieter Ibelings
>> >
>> >
>> >----- Original Message -----
>> >From: "Pieter Ibelings" <elpieter@hotmail.com>
>> >To: "guy lemke" <guy@com-pair.net>; <amsat-bb@AMSAT.Org>
>> >Sent: Sunday, May 20, 2001 14:29
>> >Subject: Re: [amsat-bb] S-band receiving requirements
>> >
>> >
>> > > Hi Guy,
>> > >
>> > > You can get as defensive as you want, but maybe you should not be
buying
>> > > those crummy connectors. I deal with N connectors every day and I don't
>> >rely
>> > > on what others say. I do all the measurements myself. I have the latest
>> > > model HP8753ES 3 GHz network analyzer on my bench and I have never seen
>> > > losses that high. If you are getting 0.5 dB, your connectors can be
rated
>> >as
>> > > "radioshack" quality.
>> > >
>> > > Pieter Ibelings
>> > >  N4IP
>> 
>> ------------------------------------------
>> Dr. Jerry R. Pixton, PIXOS Designs LLC
>> http://www.pixos.com/designs/
>> jpixton@shentel.net
>> ------------------------------------------
>> 
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