[PVRCNC] Re: PVRCNC Digest, Vol 29, Issue 9

[Robert Whitaker]

There sure is a noticable bump on the scope of the TDR
when UHF conn. are used versus (n) type conn. or New
conn.

Also, There is some waterproofing(Water resistance
would be a better term.) built in to the N type
connectors verse UHF conn.

Stay away from crimpon connectors of all types.
They are JUNK!

Butyl Mastic,(Raw Rubber) should be used at all
connections exposed to weather.
There should also be a courtesy wrap ie; a prewrap of
sorts put over the entire area to be covered with the
raw rubber using a good quality black tape. (Because
if you have to cut the seal away it makes it much
easier to get the crap off of the connector)

Another layer then applied over the raw rubber
overlapping its self 1/2 the width of tape used.
for a total of 3 passes.

Never stretch outer wrap on the final pass to prevent
unraveling of tape over time. cut it and firmly round
out the whole connection covered using a twisting
motion with your hand.

Black tape alone will not water proof any connection.

The Station here is over 90% 50ohm. 7/8" hardline.
Some of the runs are over 300'

The TDR has been put on every feed line from the patch
panel to the actual feed point of all antennas.
even the slightest change is very noticeable on the
scope and the biggest ones generaly are where UHF
connectors are installed in jumpers to feed points
etc.

In my humble opinion any loss that can be prevented
should be even at HF frequencys.

N conn. arent really that hard to put on and for the
most part. most of the ones for 7/8" line are
sorderless and can be professionaly installed with
general hand tools. small file,small wire brush,good
razor knife.quality hacksaw with fine tooth
blade.Medium sized flat blade screwdriver,
assorted wrenches or good Channelocks will usually get
you by.

I am convinced that the lower loss line here is a
tremendous advantage for both receive and transmit.

Just do the comparisons on any of the available line
loss calc's and make up your own mine.(using LDF 50
xxx
against the rest)

Everyone really should measure there output power at
the feed points of there antennas.
I think you would be astounded by the actual
output(loss) even on HF.

I am in no way criticizing the use of UHF conn.

I simply want share with others my conclusions.

Robert Whitaker
KG4NEP/
W4WS Contest Group
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>    1. UHF/N connector comparisons. (alsopb)
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----------------------------------------------------------------------
> 
> Message: 1
> Date: Thu, 15 Jun 2006 23:45:38 +0000
> From: alsopb <alsopb at gloryroad.net>
> Subject: [PVRCNC] UHF/N connector comparisons.
> To: pvrcnc <pvrcnc at mailman.qth.net>
> Message-ID: <4491F122.2000303 at gloryroad.net>
> Content-Type: text/plain; charset=us-ascii;
> format=flowed
> 
> Guys,
> 
> The following link written by K2RIW (famous for
> VHF/UHF stuff) 
> provides data on how useful UHF connectors are for
> up to 70cm.
> 
> http://www.k5rmg.org/UHF-con.html
> 
> It concludes that up to 70cm, UHF connectors are not
> a loss or SWR 
> problem.
> 
> This mirrors experiments done by some Italian
> stations who ran up to 
> several KW into UHF connectors and measured their
> loss via a 
> calorimeter.  Again, loss not an issue in the below
> 500 MHz region.
> 
> Another statement.
> 
> "There are probably twice as many amateurs who can
> do a good job of 
> installing a UHF connector on an RF cable, as
> compared to a Type N 
> connector. The proper installation and WX proofing
> of a Type N 
> connector requires considerable finesse and
> experience. It's almost an 
> art form."
> 
> 
> 73 de Brian/K3KO
> 
> 
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> End of PVRCNC Digest, Vol 29, Issue 9
> *************************************
> 


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