Trouble making my low end TDR work, Help.

amdx · 2020-04-30T14:31:48+00:00

I bought this TDR a few years ago, I used it on on a long wire on the ground to calculate the antenna surge impedance, I saw a nice step in the trace, it worked fine. Now my buddy bought one, and has a square wave on the scope, but can't get a step in the waveform, with an open cable on it. So he ask me to take it home and test it. I can't get it to work either, and now, I can't get mine to work! Both have a nice square wave output. I put a 12 ft coax cable on it without any termination, no step. I put a long (100ft?) coax, that is wound on a spool, I get a small dot like it is a very short step, but hardly noticeable. What can I hang on the output that will show a definite step or any waveform just to show it works. (C, L, LC, RL ??) It a 50 ohm output impedance, I temporarily modified mine for 500 ohms output for testing a high impedance antenna, had a step at 50% of the voltage. Mikek

Apr 30, 2020 21 Replies

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Tom Gardner 6 years ago

Perhaps

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They also sell on fleabay

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Clifford Heath 6 years ago

I played with resin and elastomer casting a few years back, built a vacuum rig and everything, but had limited success due mainly to not having the right resins available. I had already learned to trust Smooth-on, so I should get some and resurrect the skills.

Thanks for the reminder.

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