[TowerTalk] Coax Comparison Chart

Jim Lux jimlux at earthlink.net
Wed Jul 2 10:46:39 EDT 2008

-----Original Message-----
>From: Richards <jruing at ameritech.net>
>Sent: Jul 1, 2008 9:20 PM
>To: Gene Smar <ersmar at verizon.net>
>Cc: Tower Talk List <towertalk at contesting.com>
>Subject: Re: [TowerTalk] Coax Comparison Chart
>Yeah.. me neither... I kinda liked the layout of the data on the web page
>I first referenced, but wondered whether there was better or more accurate
>info elsewhere.   I hate to use something without knowing whether or not it
>is accurate.   There is so much good, and plenty of lousy, inaccurate info
>out there, it is hard to know who to trust.  

Well.. the traditional approach in publishing is to see if the author of the page says where the data came from (it's unlikely that they measured them, after all).. Presumably, the table is copied from some other reference source, or, uses some data (e.g. k1 and k2 parameters) and is then regenerated.  The question then comes up of whether there were any transcription errors or other bugs in the table. Since raw data cannot be copyrighted, but specific tabulations can, it's not unusual to put deliberate (small, insignificant) errors or spurious entries in a table to find cases of wholesale copying.. it's like sentinel names in a mailing list..

Mind you, website builders tend to be pretty cavalier about throwing up data without attribution...

Be aware, too, that coax loss and propagation properties for the generic type names (e.g. RG-8) vary a lot among manufacturers and runs. The (now obsolete) RG specs mostly gave requirements for physical dimensions and basic construction, but didn't have tight specs on things like loss. Unless you have a specific mfr and part # (e.g. Belden 1234), there could be fairly substantial differences.

Jim, W6RMK

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