Coil Swap For My TDI Beach Hunter

[karelian]

Tony the mono coils work very well in hot ground on the Tdi machines. Much better than the duel field coils, this is obvious when it comes to ground balancing the machine and ground noise.  As  per earlier posts no surprise you are having difficulty with the larger 12 inch duel field coil. 

In my experience if you were to hard wird a coil on the Tdi Beachunter, my choice would be limited to mono coils. Second I would not go under eight inches or over ten. Thus my advice is limited to coils I have used on both the Tdi Pro and Tdi Sl.  First choice would be a Whites coil, the Super Pulse 220. It is 9.5 inches and a mono. Ground balances and performs well. Hard wired it would be a great do all coil. Much better on small targets than the larger 12 inch White's mono. Pity Whites didn't offer this size coil as an option, earlier White's beach PI machines had this size prior to the introduction of the 12 inch duel field coils. 

Second pick would be the Detech 8 inch mono, very sensitive, high performing and water proof. Solid construction and highly recommended. Suspect both coils would have 'flotation' issues etc. Both are my 'ideal' size and do the job as all rounders. I suspect the White's coil would be easy to obtain in the USA and the Detech simpler to find in Australia.

If it was me, I'd put the White's Super Pulse 220 on the Beachunter, hard wired it would be my ideal.  A White's coil on a White's machine. You could always swap it back if it didn't work out, so don't cut off too much cable etc whatever you do.. Should mention this coil works well on the beach and the goldfields. I've tested it in Victoria's goldfields, no issues with ground balance, quiet operation, smooth and stable performance. Much quieter and easier to use than any duel field or folded mono coil. 

All the best.

 

[karelian]

That Super Pulse 220 mono coil uses the time proven 9.5 housing so common on earlier White's. So scuff plates are easy to replace and coil hardware is all White's. Performance on the Tdi Sl is good, particularly with the higher voltage battery pack. A great all rounder.  The small 6 x 4 Tdi coil is super easy to ground balance and super quiet on the hottest ground, but is so small I rarely use it. If you can find one, pretty rare are the White's 7.5 mono coils made for OZ, good for the goldfields but maybe a bit small for the beach?

Another option would be the Razorback 10 x 6 mono, super light weight, good performance and decent coverage. Not sure how it would work out hardwired on a Beachhunter, but in hot ground it would be easier to ground balance and operates a bit quieter and smoother.

 

[Tony]

On 4/19/2020 at 7:33 PM, karelian said:

That Super Pulse 220 mono coil uses the time proven 9.5 housing so common on earlier White's. So scuff plates are easy to replace and coil hardware is all White's. Performance on the Tdi Sl is good, particularly with the higher voltage battery pack. A great all rounder.  The small 6 x 4 Tdi coil is super easy to ground balance and super quiet on the hottest ground, but is so small I rarely use it. If you can find one, pretty rare are the White's 7.5 mono coils made for OZ, good for the goldfields but maybe a bit small for the beach?

Another option would be the Razorback 10 x 6 mono, super light weight, good performance and decent coverage. Not sure how it would work out hardwired on a Beachhunter, but in hot ground it would be easier to ground balance and operates a bit quieter and smoother.

Thanks for the detailed response, much appreciated.

Detech do a nice 8” or 11” mono.......11” is tempting as a good size for the beach and (potentially) gold fields...if I go down this route. Coiltek also do a nice 9” Elite mono. I don’t use the TDIBH in the water so a light floaty coil is no problem at all.

I shall update if this goes ahead.

 Thanks Tony 

[Tony]

I’d like to try this coil on my TDIBH

 

[Skull diver]

Jeez...I'm in love with this post!

I'm looking for another coil on my TDIbH cause of saltwater (shallow) bad influence on the original one...

It seem that only with higher delay the machine is able to divehunt silently or stably in threshold...

I use however the ground bal only as a sound discriminator between high and low conductors, as the sand and the bottom in my coast are not so bad to require it.

My question is...Can I still use the two sounds mode with a mono coil?...

Actually I don't remember why, but there's a post somewhere wich talk about this thing...I think not🤔...

Hardwiring outside from the control box a real good waterproof male/female connector will be the hell's second phase for me💀🤣

 

[Steve Herschbach]

8 hours ago, Skullgolddiver said:

My question is...Can I still use the two sounds mode with a mono coil?..

The dual field is a mono coil within a mono coil; nothing changes about the operation of the detector. The theory of the dual field coil is you get the depth of a large coil with the small item sensitivity of a small coil. However, you are exposing more windings to the environment.... soil, saltwater.... and so you get more ground or saltwater feedback than you do with a plain mono coil. The TDI Pro Oz series shipped with plain mono “Aussie” coils because of this. The standard TDI dual field coils were hot enough to be problematic on a lot of Australian ground.

Eric Foster developed the TDI circuit originally for beach detecting, and he thought an 11” round mono was an optimum coil size for beach detecting. As a ring hunter I would personally prefer an 10” - 12” plain mono coil over the dual field coil on a TDI Beachhunter. This would minimize saltwater effects while providing optimum depth on gold rings. You would lose some sensitivity to small items like pendants, ear rings, and chains compared to the dual field.

[Skull diver]

2 hours ago, Steve Herschbach said:

The dual field is a mono coil within a mono coil; nothing changes about the operation of the detector. The theory of the dual field coil is you get the depth of a large coil with the small item sensitivity of a small coil. However, you are exposing more windings to the environment.... soil, saltwater.... and so you get more ground or saltwater feedback than you do with a plain mono coil. The TDI Pro Oz series shipped with plain mono “Aussie” coils because of this. The standard TDI dual field coils were hot enough to be problematic on a lot of Australian ground.

Eric Foster developed the TDI circuit originally for beach detecting, and he thought an 11” round mono was an optimum coil size for beach detecting. As a ring hunter I would personally prefer an 10” - 12” plain mono coil over the dual field coil on a TDI Beachhunter. This would minimize saltwater effects while providing optimum depth on gold rings.

Thanks a lot for your words about it!

I'm oriented to an 8" coil, (Detech mono)especially cause I dive and always try looking on Rocky environment when the erosion appear.

I learned in the past that a smaller coil can be pushed higher in sensitivity, so the perfect size will be 8"for me...

Hopefully in the future i'll be able to reduce the higher delay of 14ms to 10ms and don't hear too much drift noise changing the coil.

[GB_Amateur]

5 hours ago, Skullgolddiver said:

I'm oriented to an 8" coil, (Detech mono)

Does that coil work on a TDI?  I realize it was White's intention that coils made for the GPX would work on the TDI, but I don't think that turned out to be the case in 100% of coils made for the GPX.  DetechUSA's webpage for the 8" mono coil doesn't mention the TDI.

 

[Skull diver]

2 hours ago, GB_Amateur said:

Does that coil work on a TDI?  I realize it was White's intention that coils made for the GPX would work on the TDI, but I don't think that turned out to be the case in 100% of coils made for the GPX.  DetechUSA's webpage for the 8" mono coil doesn't mention the TDI.

 

Actually I have the same doubt 🤔...Is a bit weird as I found on Amazon the coil straight from Detech factory and there is TDI mentioned...On their website (dedicated one for Italy)also appear wrong coil (same dd picture with different details), but also the bolt hole seem to be for Minelab and not for White's...What can I say....Need to contact the factory to better understand what they say about...

[karelian]

Detech 8 inch mono for the GPX works very well on the Tdi Pro and Tdi Sl. Excellent performance, very sturdy and well built coil. Yes it mounts on a GPX lower rod that fits well on the White's upper. Water proof but I'm not sure how deep it is rated. At wading depth and on land it is a superb coil. If I only had one coil on my Tdi machines it would be the Whites Super Pulse 220, Detech 8 inch mono for beach use, or the Nugget Finder Sadie for prospecting. All the best.