Posts Tagged ‘transmission line’

LHS Show Notes #057




  • Richard and Russ talk about the origins of the LHS podcast name. See Linux on the Desktop podcast.
  • Richard talks about how to build a Delta loop antenna, and using a piece of 75 ohm coax to act as a matching transformer between the antenna and the 50 ohm feed line. He also describes velocity factor for coaxial cable. Here’s an illustration of a 20m Delta loop similar to what Richard describes.
  • Just for fun: Fab’s Crap Alert
  • linSmith, in the Debian repositories, is a program for plotting Smith Charts, and more.
  • Richard then talks about Henry Allen W5TYD, formerly K5BUG, of Texas BugCatcher antenna fame, and the inductors he wound around Plexiglas forms. (Henry ceased production of his antennas in 2009 and has retired. -Ed.)
  • Russ uses an Alpha Delta DX-CC multiband dipole, in preference to a G5RV dipole.
  • Other antennas mentioned:
  • Impedance of transmission lines: 50 ohms for communications coaxial cable, 75 ohms for cable TV coaxial cable, 300 ohms for the old TV twinlead, 450 ohms for window line, and typically 600 ohms for ladder line.
  • Richard explains Standing Wave Ratio (SWR).
  • Richard relates an Field Day story from several years ago… Commodore-64 running packet radio on the tailgate of a truck in 100-degree heat, and burning up the C-64.


  • Audio feedback from Frasier K. thanking our hosts for the podcast. He’s currently studying for his ham license via HamTestOnline, and learned about Linux from the podcast. He’s now running Ubuntu 10.10 on his laptop and rockbox on his iPod. He’d like some sort of automatic calendar reminder service to alert him when a new episode will be recorded. Thanks, Frasier, and we’ll look into that.
  • Mitch, KC2MBN, says that he enjoys the podcast. He’s now an Extra class licensee, but is new to Linux. He recently tried dual-booting Windows 7 with Pinguy OS and reports some troubles, and asks for some recommendations for a distro. Thanks, Mitch. If you have a spare machine, it would be better to run Linux on that rather than going to the trouble and risk of dual-booting. You might try actual Ubuntu, Debian or Linux Mint. Crunchbang Linux is also easy to install, as is PCLinuxOS.

Contact Info:


  • “Bad Boy (For You)” by Rebolt from the album “Made in Spite EP” courtesy of Jamendo.
  • “Daylight” by Singleton from the album “The High Seas” courtesy of Jamendo.

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