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Some of the DD coils I’ve bought over the years sound off with an alternating high-low frequency tone. They don’t detect a target. Is this an incompatibility or a bad coil? I do have DD and mono coils that work ok.
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Sounds like bad coils. I would measure the inductances. -
Check the connector solder joints. I have purchased three non working gpx/sd coils over the last few years. All had shorts or breaks at the connector. Its a tiddious job to repair because of the litz wire shielding. The cable is stiff so the connections are stressed. Two of these coils have the outer insulation flaking off but work well for bench testing.Comment
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Resistance and inductance check don’t point to anything radically wrong. Maybe a trend in being slightly lower inductance than working ones. Does the same thing on both my GP Extremes. Messing with the normal/E/cancel switch puts it in one mode where there is no threshold and it has some target sensitivity but not much. Does this on both mono and DD’s, and I also have working coils of both types. One bad one is for SD series only, maybe that’s a clue. Others are for GP so should work. Connector pins and internal wiring good.Comment
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Post the inductance and resistance for a good coil and a bad one. It may take less variation than you think.Comment
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I marked my measurements on stickers on the coils and just shipped them on a trade. He still wanted the “bad” coils to try on Gpx series detector. An example for a DD may be good 625/301 vs bad 611/310. A mono commander 11” bad was 3.4 ohms which is low and 308uH which seems ok. A working 8.5” one was 305uh.
oh well they’re gone now.Comment
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