WHITES GMT Goldmaster information and questions

[Guest]

Camera batteries are best and hold current well but pricey iv always wanted to try the whites rechargeable pack has anyone ?

Was thinking about one for my SST but then read this:

The White's Rechargeable Nicad battery will not provide the same amount of continuous use as a full set of Alkaline batteries.

Would be ok if your close to home & can charge it regularly or have an alkaline set spare but for $145 you would be better off with normal rechargables or lithium rechargables that can be replaced by cell rather than the whole battery pack I.e. if one or a few batteries prematurely die then you can replace those if 1 or more cells go in the pack you would need to replace it as a whole?
Whites manual says the alkalines will still allow normal operation even just below 8v, although I would still stick to replacing at 50% or around 10v to ensure max performance, while any rechargables are "dead" at 8v & require recharging.
One of the first things that happens, according to Whites, when the voltage is getting low is a drop in volume so to make sure your getting those faint signals keeping voltage at those optimum levels is a good idea.
For mine I'll stick with alkalines until I come across a good, reasonably priced rechargeable lithium system.

 

[Still Looking]

The 30 pk duracells from Bunnings look to be the go for the exterra 305 ..thanks for the info..

 

[Sparra]

Hey fella's...I have had my GMT for a total of 3 days and been doing a bit of playing...I lost a small sinker in long grass in the back yard but found it again today so it is working...Just a question with the ground balance...In auto tracking do you still need to push the grab button or does it automatically ground balance when you first turn it on??? If you need to use the grab button to balance do you hold it in while pumping or just push,release and pump???
Hope this makes sense...

Cheers...Sparra

 

[Guest]

As you sweep it will automatically ground balance in auto trac' you can also press grab and it will jump to the ground you were just on but as you sweep further on it will continue to change ground balance it does work well and simple to use.

 

[Sparra]

Cheers...Thanks mate...

 

[Roscoe]

#8 Modifications. External speakers such as these Nokia MD-11 booster speakers work well with the GMT. They use AAA batteries and link together, its a good cheap alternative to not wearing head phones.

 

[Guest]

Good stuff Roscoe' il post some pictures of mine though it's not part of the unit I use mine on all my machines only down fall is I'm not separate from the detector .

 

[Guest]

Iv made a few of these now quite simple to build cost was around $30

 

[Greglz86]

Thanks for all the info zuke and rosco.
Hope this helps me next time I get out
Greg

 

[Guest]

#8 Modifications. External speakers such as these Nokia MD-11 booster speakers work well with the GMT. They use AAA batteries and link together, its a good cheap alternative to not wearing head phones.

https://www.prospectingaustralia.com/forum/img/member-images/1615/1396382258_picture_014.jpg
https://www.prospectingaustralia.com/forum/img/member-images/1615/1396382258_picture_013.jpg

Nice set up - now where have I seen that before :lol:

 

[backcreek]

Hay Guys,
Great post for us using the GMT.

I don't use mine that much in the bush any more although it travels with me every time I go out.
I use it mostly to check my tailings for missed nuggets (ha, if thats ever going to happen) or specimens.

Anyway when I was using it the bush I found that if the coil lead was allowed to move on the shaft that it would false signal so I just taped it to the shaft every 3" of so and problem solved.

I know it's a common problem but I thought I'd put it up as some may not be aware of it.

Hay ZL,
How about some more details on the external speaker, the pics are a bit hard to get any detail from.

cheers
Mick

 

[Guest]

No worries: the amp unit is a USB powerd 2 ch head phone amp bought on eBay for around $10 ,old head phone lead wired for stereo.
The spk is a handheld uhf mic also bought off eBay for about $15, removed the circut inside and conected 2 wires to the spk, then iv bridged it across both ch by - one ch + the other.
Wired in the cut down 4x battery tray to make close to 5v and for the moment pinched a small container from the kitchen. Now that it works realy well I'll redo in into a electronics box with a remote button so when someone's yelling at me I can choose to listen or not

 

[Sparra]

Hay Guys,
Great post for us using the GMT.

I don't use mine that much in the bush any more although it travels with me every time I go out.
I use it mostly to check my tailings for missed nuggets (ha, if thats ever going to happen) or specimens.

Anyway when I was using it the bush I found that if the coil lead was allowed to move on the shaft that it would false signal so I just taped it to the shaft every 3" of so and problem solved.

I know it's a common problem but I thought I'd put it up as some may not be aware of it.

Hay ZL,
How about some more details on the external speaker, the pics are a bit hard to get any detail from.

cheers
Mick

Thanks for that...I went out today to try out a new coil and noticed I was getting a lot of false readings and I think this may of been the reason...

Cheers...Sparra

 

[GMT Bandit]

Well I can honestly say I've been bitten by the gold bug....well actually it was a bull ant and god it hurt!!!!! Damn thing bit through my jeans. Took a week to get over. Oh the pain.

 

[KarlS]

No they won't - you'll get spurious noises & other issues. Use as a minimum good quality alkaline batteries. I always used Duracell alkalines & got around the claimed 30-40hrs detecting time before they reached the 50% mark.
Lithium rechargeables might be ok but others will give similar poor results as poor quality or less than alkaline batteries.
Reasons:
Normal battery (heavy duty, general purpose etc.) 1.2v max output
Alkaline battery 1.5v max. output. Because the voltage of an alkaline battery drops at a very predictable rate: 1.5 volts - fully charged, 1.25 volts - 50% charged, 1.0 volts - at the end of its lifecycle. This is why you discard @ 50%. Still around 1.25v or slightly higher than the cheaper types even after nominal 30-40hrs detecting.
Rechargeable batteries are usually all 1.2v max. output
Lithium rechargeable batteries 1.5v max. output.

Basically with anything less than alkaline batteries you are starting off flat.
With 8 x alkalines you start at 12v & finish around 10v @ 50%
Cheapos you start at 9.6v

This is incorrect . All nonrechargable batteries regardless if they are alkaline, heavy duty, or carbon zinc are 1.5 Volts . And all of them are fully discharge for most of applications when the voltage drops to 1,2 Volts. The internal resistance of battery increase and the battery can not supply required current. Rechargable NiCad type battery internal resistance at 1.2 Volts is low and that's why it can operate in most of applications past the 1.2 Volts.
There is new type rechargable battery that is fully charged 1.6 Volts. ZnFe, look it up on eBay. I'm using them in Pentax camera and in Exterra 705.
Karl

 

[KarlS]

Correction to previous post, 1.6V rechargable batteries are NiZn , nickel zinc, not ZnFe as in my previous post. My tablet do this to me all the time. I type something and it prints something else.
Karl

 

[Guest]

My GMT arrived from the USA.

I am very impressed with what I have seen just playing with it.

It cost $550 AUS and included delivery and got a 4" swedish made knife with belt pouch with it though it
was used once the guy sells these and threw it in.

Had the gmts serial verified by the man himself Jimmy S.

Its in excellent condition and coil looks new.

Very happy with purchase.

 

[Guest]

You got a great deal there Wolf now you need to find a old quartz crushing site to rake over'

 

[Guest]

It's an impressive detector.

It zaps over small nuggets as well.

Going to test it were the ground is nearly bedrock and where I have found gold previously with my
other vlf.

 

[Guest]

The trick is to get the gain as high as possible by increasing the SAT speed.
They are very impressive detectors and iv done quite well with mine the last few years.