RE: [amsat-bb] Flexible Coax

["Ray McKnight - WB3ABN" <shortsheep@xxxxxxxxxxxxxxxx>]

Bill, I've not heard any comments regarding water intrusion in LMR.  All
of the discussion on this reflector has focused on 9913.  There have
been a lot of stories told about "draining" your coax, but it's always
9913.

I think there a lot of amateur Amateur's when it comes to the radio art.
Merely slapping a connector on the end of a piece of coax and wrapping
some electrical tape over it doesn't cut the mustard.  What most people
don't realize is:

1) EACH brand and model of coax has a proper connector and several that
will fit but are NOT the proper connector.  N's designed for 9913 are
NOT appropriate for LMR.  To do the job right you need to use the
specific connector the coax manufacturer states.  Often this means
buying a much more expensive connector than the junk available at Radio
Shack. Most connectors sold by Times Microwave for LMR400 are about $20.
Most hams won't pay that. You must be especially careful when using
connectors made by someone different than the coax manufacturer or who
they specify.  There are a million different N connectors floating
around and most look pretty much alike.

2) The best way to terminate is using a professional crimp tool (and of
course a crimp certified connector).  Most hams will not spend the
$100-$200 for the tool and appropriate die for the specific connector
they are using.  They also won't usually buy the $65 stripping tool to
get a perfectly prepared cable.

3) Now, the real meat of this debate lies in the way terminated cables
are finally installed.  Regardless of the brand of coax, type of
connector etc, if it's NOT sealed properly water will intrude.  Most
hams have no clue what the proper, professional way is to do this.  They
would do well to watch a skilled marine ET since the environment on a
vessel is likely the harshest place to put an antenna and if water is
gonna get in, that's the place it has its best shot!  I'm not blaming
hams for being hams, it is just a hobby.  But let's not use this as an
excuse to label 9913 as bad coax.  

I hate hearing this debate over and over, blaming the coax or the
manufacturer for poor quality when it's just a bad installation.  Water
does not magically seep through the outer jacket UNLESS it has been
damaged in some way.  The only other explanation is an improperly sealed
connection.  It's not the connectors' job of keeping water out! It's
there to keep RF in. Even coax that uses solid dielectric can wick
water, not just air insulated styles.

73's
Ray - WB3ABN
Kingston, WA

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org] On
Behalf Of Bill Acito
Sent: Friday, October 18, 2002 10:57
To: John K9IJ
Cc: amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] Flexible Coax

Thanks John. I have read that the same characteristics (Air gap?) that
make LMR400 a good performer also make it susceptible to water
infiltration. Is LMR400 Flex also susceptible?

Bill
w1pa


----
Via the amsat-bb mailing list at AMSAT.ORG courtesy of AMSAT-NA.
To unsubscribe, send "unsubscribe amsat-bb" to Majordomo@amsat.org