noisy coil

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I recently had an issue when trying to pinpoint targets with my 11" standard mono coil, I would get strange interference signals when I tilt the coil sideways. When I get home from weekends out I generally clean all my gear down before packing it away. This time I thought I would replace the tape around the skid plate, it did not look too bad, but bugger me, when I took the plate off I was surprised at the amount of buildup there was. I could clearly see that when I was pinpointing and tilting the coil on its left side(mono) this build up of iron rich grit between the plate and coil would accumulate in that one corner. It must have been causing a slight interference in the Signal.
I have since had a look at all my coils and again where I thought the tape had everything all sealed up, the fine dust built up over time was evident. It could be worth your time to check your coils often. Removing any unwanted false signals is going to help hear those faint target signals.
I also repaired a fine crack in an older Nf coil using a soldering iron, I will post that up when I fix the images.
Cheers
Deano

Another image showing the dirt accumulated in the corner as if pinpointing using the coil on its side.
Deano.