[MyHosting.com]   [KO4BB Home Page]   [Manuals Home Page]   [KO4BB Wiki]
 

Differences

This shows you the differences between two versions of the page.

Link to this comparison view

ham_radio:semi_rigid_cable [2013/01/08 19:00]
ham_radio:semi_rigid_cable [2013/01/08 19:00] (current)
Line 1: Line 1:
 +====== Semi Rigid Cable ======
 +
 +//On Tuesday 29 January 2008 15:07, Richard Gill wrote://
 +
 +//A few years ago I bought some Semi-Rigid Coax from out favorite bid site for later use. I am building some Yagi's as described in the Aug 2006 QST article by Jim, W6PQL. The yagi's use a piece of UT-141 Semi Rigid coax as a balun. The coax I have has no ID or number and does not look like the coax in the article. Anyway the coax I have has the follow specs: appears to be made of Copper tube.//
 +
 +//Has a OD of .141"//​
 +
 +//ID of .120" ~//
 +
 +//Insulator is a white plastic looking material.//
 +
 +//Center Conductor is solid wire. 20Gauge (.0365"​ Dia) and may be silver wire. Not Copper.//
 +
 +//Each Piece has a SMA Connector soldered on the end.//
 +
 +----
 +
 +Steve VE3SMA replied:
 +
 +It looks like the right stuff. UT-141 is one manufacturer'​s name for what is more generally known as MIL-C-17/​130-RG402,​ which has .141" OD (bare copper), .119" OD PTFE insulation and .036" diameter inner conductor (silver plated copper-covered steel).
 +
 +There are many similar variants with different outer conductor materials, etc.
 +
 +The impedance formula should be
 +
 +Zo = ( 138/SQRT(e) ) * log(D/d)
 +
 +where SQRT(e) means "​square root of the dielectric constant"​ and the log is the base 10 type. It comes out to 49.4 ohms using the above dimensions and e = 2.1 which is what my reference gives for PTFE.
 +
 +73,
 +
 +Steve VE3SMA
  
 
ham_radio/semi_rigid_cable.txt ยท Last modified: 2013/01/08 19:00 (external edit)
 
Recent changes RSS feed Creative Commons License Donate Powered by PHP Valid XHTML 1.0 Valid CSS Driven by DokuWiki
Except as noted, this entire site Copyright © 2002-2017. KO4BB All rights reserved.