Book Excerpt: “How to Run “10 kHz” as a Cap / Iron Identifier”

18/ How to Run “10 kHz” as a Cap / Iron Identifier

A lower frequency like “10 kHz” is what can be called a “plodder.” It responds slowly, makes sure its reporting accurately and only shows a couple of numbers to describe what it sees. When you run “10 kHz,” make sure to give it the time it needs to do the task. Switch over, wait for the threshold to return and make a slow, even coil pass. Just as with “Multi” the first numbers that appear may be cap or gold-range indications–in the teens. However, when you go to the cross sweep (or even a slight angle) the ground becomes apparent in the forum of a ”20 plus” reading. This change will be a lot more definite than with “Multi.” So go slow to let the slower frequency process, use the cross sweep and watch for the “wild” high number indicating a cap or iron. “10 kHz” produces a more defined, more “general” meter response. This response takes into account more of the ground’s signal–making “10 kHz” a great cap identifier. (This is also a great illustration of the dichotomy between what the high and low frequencies actually do).

The idea though is to work on your coil and meter recognition skills so that having to make the change-over is a last resort for only those caps that display a very narrow band of numbers in “Multi.” These are in the minority. I especially go to “10 kHz” where the indication shows “14”–again–a good gold number.

(Note: If you are using the 800, in “5 Tone” a high “Tone Break” of around “19” or “20” will produce an intermittent high tone on caps with this test.

Another interesting lesson to be observed when running “10 kHz” is that if you make multiple passes of a target sometimes the slowed response speed will cause the meter response to “double up”–that is it gives a “cumulative” high number. This is something to watch for in that a response can be falsely “ID’ed” as higher than it is–in this case a worse signal. Referring back to our “coil control pass types” above, this kind of a response comes from making “keep in” passes–instead of letting the target leave the detection field each swing (so as to “reset” the meter). Both have value in identifying responses but it’s good to be aware of the difference.

It’s important to recognise the parallels between this machine and the CTX. With the CTX this “grounded” number comes in the form of a “1” or “30” “off screen” response–indicating iron or steel (non-constancy). I’ve heard these referred to as “cross-feeds” In that they initially sound good as the two parts of the response “connect” on the first pass–but this electrical “join” is then rapidly processed out with subsequent coil passes.

With the Equinox these indications are more centered on the meter–“10” for rusted caps or “20” plus for steel caps. It’s more like where you have a coin next to iron–pulling the response down (or up towards the “wrap” zone). With an analog detector–either of these (CTX or Equinox “outlying” numbers) would be the low tone (or “nulls)” of iron mixed in to the audio response, or a high “sound off” or “false.”

From: “The Minelab Equinox: An Advanced Guide” (2018)

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