Minelab GPX4500 tips, settings, questions

Scrounger ..... No question about it ....... I am on a mission. 6 months detecting with a VLF without one piece of gold, and watching you and others cleaning up. I've been so jealous. Still a lot to learn but trust I've got the right tools now.
Don't hesitate to say g'day if you see me ...... I drive a white Renault 4 door sedan. Not my car of choice and certainly not much chop for detecting; but it's a work car and I don't have to pay to run it.
Hope to see you, and any others out there.
Cheers Andy/Dig'n-it

Just a question on Stabiliser...normally sudjested 2 under Rx....when I was playing with the settings the other day I wound the stabiliser back to 1 and found it ran quieter and picked up the target stronger...but I don't know why...Cheers..have seen it talked about somewhere ..

Many thanks for the feedback old hand, G0lddigg@ and mbasko.

mbasko said:

You shouldn't be confusing EMI & ground noise.
With EMI you will be getting spurious noises with the coil motionless.

With the coil motionless & you have no spurious noises until you start to move it then you've got ground noise.

Don't get caught up too much in recommended setting numbers. Adjust to suit the area & what's going on that day.

Click to expand...

That clears things up very well for me, I can say with certainty that my problem was, save the brief air show, Ground Noise.

Next Trip
Soil/Timings: Enhance
Ground Balance: Fixed

Motion: Slow

Ground Balance (manual pages 42 and 43), check often and if in doubt, do one again.

As for Rx Gain and Stabilizer, what should I listen for when setting this up?
Also am I right in thinking Rx Gain gets set first, then Target Volume and Stabilizer or have I missed something else?

I'm not afraid to experiment with these settings; just making sure I have the right set of steps ironed out and and what I should listen for when tinkering with a setting at each step.

The rest is starting to come together in my mind though; I may yet get the hang of this beast

Congrats to the other recent posters for joining me in owning this detector and I hope my probing and prodding here helps you all learn how to use it as well.

Hi w3bgold
I just got my 4500 today and the instructions are fresh in my mind. Page 71 of the instruction manual States:
1. Select an appropriate search mode
2. Select the desired audio type
3. Adjust Rx Gain until the threshold starts to break up
4. Adjust Stabilizer to smooth out the threshold
Hope this helps.
Good luck.
Cheers Dig'n-it

Hi w3bgold. I'm relatively new to detecting and I have a 4500. I met fellow prospector out in the GT and he wanted to see how my 4500 with an 8" compared to his Sdc 2300. He had plenty of sub grammers on him. He pushed one of his tiny nuggets .1g about 1 inch under the soil and covered it. I swung the 4500 and just got it. He then ran me through altering some of my settings. By the time we were finished mucking around my 4500 hundred was easily hitting the tiny nugget. Now every time at the start of detecting I'll bury a target (lead shot or gold) and muck around with the settings until I am happy with the signal.

Is too and quoted by mbasko. :8

Rx Gain under threshold breaks up, then Stabilizer to smooth it out.
Re-reading the manual page 73 answers where Target Volume comes into the Equation as being a final adjustment.
Up to boost audio and down to drop extra chatter.

Very quick post Dig'n-it

Chuky boy said:

Now every time at the start of detecting I'll bury a target (lead shot or gold) and muck around with the settings until I am happy with the signal.

Click to expand...

May be a use for the first bullet I dug up then, besides a shelf ornament. I do recall reading that such give off the same signal as gold and is why people get so many of them.

I found a high trash like area where one or more someones have fired a few rounds at a rusty iron bucket which appear to have been for thrills. I might give a thorough look around it one day when time is plentiful, after re-checking GeoVic and relevant maps, in case there are possibly any gold signals are disguised among it that people didn't want to put in the effort to check.

I have a new minlab GPX-4500 lower shaft that seems to have the nylon insert about 5 degrees out of alignment from the snap-spring resulting in the coil and box not sitting flat on the ground and encouraging twist that I would prefer not to be there.

Before I attempt to use brute force to try and twist the nylon insert, could someone tell me if this is possible or if it is factory cemented into place?

can you put a picture of it regards john

The photo shows the control box on one leg when the coil is flat. When the box is flat the coil has one side off the ground by about 5cm.

Bummer mate, I don't know how it's fixed in there, might just have to call ML and see it can be turned somehow if it's not glued in.

Hey Wally.... the coil end the bolt goes through is usually just glued in. I'd remove it from the coil, give it a quick vigorous twist to break the seal, remove it from the shaft & clean. Then using some araldite put it back together with the box & coil flat and allow to cure.

I've bought a new shaft in the past and the end fitting was actually loose from new, perhaps yours is too? Try it out, their a very basic fitting, and the end piece is cheap enough if it breaks for replacing.

Alternately, if it's a new one, return to place of purchase and exchange???

Gypsy

2 thinking you can do 1/ take the hole thing back to the dealer and see if its the upper or lower shaft that needs replacing that's my preferred way to go

2/ on the lower shaft pull the retaining pin out turn the shaft over on the coil place the upper and lower shafts together do up the lock nut mark and drill a new hole then replace retaining pin
as I said number 1 is the way to go regards john

Thanks guys, I'll get on to the dealer.

Hry Paul, is this your gpx? Or your bro in law?

The other way to align this is to redrill the spring detent button hole on the lower shaft where it joins the upper shaft, 10-12mm lower and shorten the shaft a 1/2".

Take the spring out, join upper and lower, align it, lock it with the ring and using the corresponding hole in the upper shaft as a jig, carefully drill a new hole.

condor22 said:

The other way to align this is to redrill the spring detent button hole on the lower shaft where it joins the upper shaft, 10-12mm lower and shorten the shaft a 1/2".

Take the spring out, join upper and lower, align it, lock it with the ring and using the corresponding hole in the upper shaft as a jig, carefully drill a new hole.

Click to expand...

Yep, or just drill a hole on the opposite side and spin the shaft upside down. The bottom yoke/rod part is reversible.

But yeah, if it's new, this will covered under warranty.

Reeks said:

Hry Paul, is this your gpx? Or your bro in law?

Click to expand...

It is at this point in time as I have purchased the kit for the bro in law and will be running it in to make sure it can find gold for him

I have been toying with the idea of getting a deeper seeking nugget machine that punches deeper than the SDC for a while, so it is a great opportunity for me to test a few SDC patches for some missed nuggets and get a feel for the 4500.

I'll be heading to Hill End to test it out shortly and will be meeting my bro in law up there the week before the Bathurst races.

If you can get time off, you should come and share the campfire.

Hi Rick, I picked up my 4500 this week and took three test nuggets out to the area I intended to detect.

I only did an air test with the standard 15x12 and it picked up all three no worries. The smallest piece was .2g not much bigger than yours and it gave a definite signal.

As for burying it I am still yet to try that. Not sure how deep the 45 would be able to detect a .2g piece with the 15x12 but will try that out as well. As new users of these machines we have a lot of learning ahead!

I got my new 4500 this week and took it out for the first time.

I dug a lead shot at roughly 1.5 inches, happy with that.

Moved on about 50m and got a signal. Gave the ground a scrape, signal louder. Scraped off maybe an inch of soil, signal louder again. So I thought this could be good.

After repeating this process and having a hole roughly 50cm long and about 30cm the 45 was screaming. Then.... nothing.

So I ground balanced, put the coil over the target and it screamed again, waved it over the hole a few more times and the signal died off. Tried this process a few more times with same result.

Fella at Coiltek said if you run the coil over a target too much the machine will balance out the signal?

I know there is heaps to learn but it was if the ground balance seemed to be dropping out every 10-15 seconds so that even the soil I dug out screamed at me.

Balanced again, dug out soil went quiet, target hole screamed, then nothing. I gave up, filled in the hole and will go back in a few days.

I'm aware it's most likely me not knowing what I'm doing, but I am stumped.

I used:

ENHANCE

GB General

SENSITIVE Extra

TRACKING Slow

Maybe you should of switched to Fixed, If I remember rightly they use to say in the manual about hovering over the Target, the only reason you need to be in tracking is if the ground keeps changing and even if it does keep changing, Once you find a target switch in to fixed and then the machine won't track out your target,

hope this helps,

john