[PVRCNC] Cheap TDR (time domain reflectometer)

[alsopb]

I ran across the following link:

http://www.web-ee.com/Schematics/TDR/tdr.htm

It describes a time domain reflectometer one can build for about $20. 
  Uses one IC and a handfull of caps and resistors. You also need an 
oscilloscope.  50 ohm, 72 ohm and 100 ohm source impedances can be 
handled.

With it you can identify the type and location of various cable faults 
in the range of 15' to 1500'.   The article has a sublink with 
pictures of various types of "faults" including what an coax 
terminated by an antenna look like.  Even if you're not interested in 
building one, the pictures are interesting to look at.

I've been interested in one building one of these beasties for years. 
  The cost has always been a turn off.

I understand W2PV used to use TDR to troubleshoot his antenna/coax 
problems on his huge arrays.  In his case, most repair jobs called for 
a crane.  Identifying the location became really important.

73 de Brian/K3KO