[amsat-bb] Exciting Coax

Edward R Cole kl7uw at acsalaska.net
Wed Jan 24 01:28:44 UTC 2018


Important to point out that the F7 variant of 9913 has no air 
dielectric which got the original 9913 into trouble.  Also LMR cables 
use aluminum foil shield covered with wire braid shield.  If exposed 
to water the aluminum corrodes and gets quite lossy.  So wx sealing 
is still necessary (two wraps of good electrical tape at 
minimum).  Good electrical tape = Scotch 33+

I also seal with heat shrink tubing but often cover that with electrical tape.

LMR-400 is generally good to 432.  It is not anymore flexible than 
Belden 9913.  For better flex consider LMR-400UF 
(ultra-flex).  Slightly higher loss but better to go around az-el joints.

For long runs at 432-MHz one should consider LDF4-50 Heliax hardline 
(1/2-inch) or lLDF5-50 up to LDF7-50.  Loss is higher at 1268.  I 
have 15-foot run of LDF4-50 from my tower-mounted DEMI 144/1268 Tx 
converter.  That gets the most power to the antenna and only needs 
12vdc, PTT, and 144-MHz coax to input.

Some archive photos: http://www.kl7uw.com/sat.htm
Drawing shows current satellite antenna installation.

73, Ed - KL7uW

From: Bob- W7LRD <w7lrd at comcast.net>
To: amsat-bb at amsat.org, anderson58625 <anderson58625 at gmail.com>
Subject: Re: [amsat-bb] Exciting Coax
Message-ID: <992329878.579633.1516693575413 at connect.xfinity.com>
Content-Type: text/plain; charset=UTF-8

For 2 & 70cm I use LMR400.  LMR is better (in my opinion), in that 
it's more flexable, 9913 can get water inside.  Unless coax 
connectors are super sealed.
73 Bob W7LRD

73, Ed - KL7UW
Dubus-NA Business mail:
   dubususa at gmail.com 

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