Another new addition to my arsenal of test equipment is a brand new Riser Bond TDR purchased on eBay.   A small repair was required to get the instrument to work, but the price was right.

With this instrument I get a visual picture of my feedlines and coax cables.   I can use it to determine how well my Beverage antennas are working – a mismatch of the termination shows up very clearly and faults on my open wire feeders are easily located.

In addition, the instrument was very helpful when locating shorts on my 8 km long electric fence, showing me clearly which direction to walk in to locate any faults.

Lee, K7TJR pointed out on the Topband reflector:

“The Tek 465 and many other scope models can be used as a TDR
without building any circuitry. One simply needs to take the A gate
signal out of the rear panel of the scope and connect it in parallel with
the transmission line or antenna under test at the vertical scope input.
The gate signal provides a fast rise pulse on the line under test at the
beginning of the trace. Of course the sweep must be free running.
Reflections are easily seen as a result. I have used this very
technique with both single and dual direction Beverage antennas.”

I tried this technique with my oscilloscope, switching between the GATE signal and the signal from the Riser Bond being displayed on the oscilloscope – although the technique certainly works to show any reflections, it was difficult to get any meaningful display compared to that from the Riser Bond instrument.

The VNA2180 software will be upgraded within the next few weeks with a TDR function.   That will be simply wonderful.

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