A New Concentric Coil Coming For The Earlier GPX 4500/5000 Series From X-coils

[schoolofhardNox]

Can't wait to hear how it does on the 5000. Nice that you got it just in time!

[phrunt]

Thanks, I couldn't wait for Santa so this one got opened straight away 🙂 Although it was a gift from the guys at X-coils.  Either way Santa comes to NZ first in the world anyway, so what's a day or so matter 🙂 I don't know what day it is at the best of times so I can be forgiven for opening a present early! 

I took the coil down to the river behind my house for a spin, I hadn't used my GPX in a little while so was a bit rusty on it, I did a factory reset and off I went.  

After the default settings were done, I put it into DD mode, Coin and Relic timing and left the sensitivity at default and had a scan around, found a couple of targets and marked them out, enabled discrimination with a level of 6 and it worked out one of the two targets I found was iron with the typical iron blanking.  I then thought I'd try mono mode out and discrimination stayed working, I was completely puzzled by this as I thought that was impossible.  I had a panic my DD/Mono/Cancel switch wasn't working so I quickly went home and got a DD coil and another Mono coil and tried the switch out, it was working fine so I put the CC back on and verified and Discrimination is certainly working in DD, Cancel and Mono.  So weird.  Then I wondered if the Coil was even working in mono mode so I tested a tiny gold nugget on the edge of the coil knowing a Concentric coil will not have edge sensitivity and as expected the little nugget was not detected on the edge of the coil when in DD (concentric) mode, switching to mono the nugget was detectable at the edge of the coil, so somehow discrimination can work on the GPX detectors while in Mono mode with this coil.

This could prove very beneficial for beach detecting having the discrimination while still running in Mono mode.  I'm not yet sure if running as a Concentric is deeper than mono, I've only had about half an hour's use of the coil as I couldn't stay out testing it due to having to mow the lawns before the rain tomorrow and then its Christmas so work before play 😞

I collected my Coiltek AI 11" coil when I went back home and it handles EMI better as expected I guess, the Concentric is more like running a DD, but maybe for the size of it it might be better, I didn't have a 15" round DD to compare, it ran like the 11" DD for EMI.  

It worked perfectly well in Coin and Relic timing which i believe is the most powerful mode for depth on the GPX, it has ground balance disabled for maximum depth in mild soils and it worked very well, even on maximum sensitivity of 20.

The river area I was testing is loaded with hot rocks too but somehow even in Coin and Relic mode it wasn't going nuts on hot rocks like a VLF does.

All very early days but here is a couple of videos, you will see this as I saw it, I'd not done any of the stuff in the video prior to filming the video.  I was filming it as I was doing it.  I'd accidently turned off Auto focus on my phone so it went out of whack a few times but still watchable.

I was so puzzled by discrimination working in mono mode I used a little nugget to test that the coil was actually changing into mono when I flicked the switch by comparing the coils edge sensitivity in Mono mode, then in DD (Concentric) mode, as a Concentric coil loses its edge sensitivity and indeed that is what was happening so it does switch, but somehow discrimination still works as a Mono.  Edge sensitivity isn't fantastic as it's a spiral mono, not a bundle wound coil.

Still a lot to learn yet with the Coil, as I said I've only had about 30 minutes on it, I think it may be a good beach detecting coil.

[PhaseTech]

Hi Simon, what's the weight of the coil? 

[phrunt]

39 minutes ago, PhaseTech said:

Hi Simon, what's the weight of the coil? 

I forgot to put that there 🙂

1201 grams with the taped-on skid plate, so 200 grams heavier than the NF 15" Mono solid if they include the skids in the weight, I guess that's the extra windings?

I'd love a 12" of this coil to get a bit more smaller gold sensitivity seeing that's what I mostly find yet have the discrimination features.  I think I'm going to be using my GPX 5000 a bit more next year now.

[jasong]

Thanks, and interesting Simon. Good to see reports on equipment and new things here again on the forum, this is the stuff I come here for. 

Interested to see what else you find, I still have a 4500 laying around unused and curious if there is some non-relic/beach niche for the 4500 still between the 6000 and 7000.