Timing question on 4500

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Timing question on 4500

Post  marty on Sun Dec 19, 2010 9:28 pm

Hello all,i have a question about the 3 timings - slow, med ,fast- after something i noticed while testing on a small signal last night.Does it make a difference which timing your in when searching in fixed? I was in slow timing, changed to fast reground balanced and the signal seemed to be louder( all while in fixed)tested this twice and then on another signal with the same results? Any advice would be great thanks. MARTY

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Re: Timing question on 4500

Post  GoldstalkerGPX on Sun Dec 19, 2010 10:04 pm

G'day Marty, It is not timings but the tracking speeds that you are asking about, I am not 100% sure but I would assume that while in 'fixed' tracking (also while in 'tracking' that the diffent tracking speeds do/will make a difference. Do not be confused between this and the timings.
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Re: Timing question on 4500

Post  marty on Sun Dec 19, 2010 10:27 pm

Thanks Goldstalker, yes sorry i got that all mixed up.Well looks like i might have to work this spot in fixed tracking on the front and fast tracking on the screen.Something made me think that the tracking speeds were only used in auto tracking mode and were canceled out so to speak in fixed. Thanks MARTY

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Re: Timing question on 4500

Post  kon61 on Mon Dec 20, 2010 12:03 am



G'day Marty.

Sweep speed does make a difference when searching in fixed mode.It affects not only ground balance adjustment,but target response time as well.Example; a slow or very slow motion sweep speed,coupled to the motion "slow" setting,has the tendency to allow,maximum ground noise stability and better sensitivity to small targets as well as better depth capability to all targets. On the other hand motion "fast" coupled to a fast sweep speed,has the tendency to give a slightly sharper target response,(which is what you received with your small target) allows for more ground coverage,but not recommended when chasing faint signals for big gold at depth.
On another note,Motion set in fast,also has the tendency to be more susceptible to EMI or external interference,resulting in a more unstable threshold.

Cheers kon61.
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Re: Timing question on 4500

Post  Narrawa on Mon Dec 20, 2010 1:37 pm

marty wrote:Thanks Goldstalker, yes sorry i got that all mixed up.Well looks like i might have to work this spot in fixed tracking on the front and fast tracking on the screen.Something made me think that the tracking speeds were only used in auto tracking mode and were canceled out so to speak in fixed. Thanks MARTY
A more simpler way to put it is, whatever tracking speed is set in the menu, is the GB speed when you push the green button in fixed while bobbing the coil.
Once the green button is released, whatever is in the tracking menu now has no bearing, its only when the button is pushed or while in tracking.
So its not going to help you with signal definition.

PS, to reach the tracking menu speed the green button must be held in longer then that of just the forced GB.
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Re: Timing question on 4500

Post  marty on Mon Dec 20, 2010 3:33 pm

Hi Narawa,so what your saying is what i originally thought before and that there should be no difference in the signals while in fixed? There was definatly a difference so it's probably some other reason. All i did was move the coil away from the target, change to fast tracking and ground balance for a good 5 sec maybe a bit more then wave over the target.I'll have another read of the manual then try again tonight. Thanks for your help. MARTY rendeer

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Re: Timing question on 4500

Post  Narrawa on Mon Dec 20, 2010 4:15 pm

Marty, the GB on a 4500 is pretty critical, get it wrong like most of us do at times and it will certainly give mixed reading on your target.
The use of fast tracking in the menu and holding down the tracking button while in fixed can lead to loss of depth.
Here is a question i asked JP about this some time back on another forum in blue, followed by his response in green.
JP, doe's the GB speed effect the green button operation when the detector is in fixed.
If its set to fast in the menu will this have an impact on the tracking when you push the green button when balancing?
This may have been asked before but I cant find reference to it and its bugging me.

Only if you keep the button depressed longer than the forced GB time frame then it reverts to the preset speed (Fast, Medium, Slow), I usually like to press then release then depress again when balancing if the GB is out by a lot. You have to be careful with a too fast a GB as the averaging can actually prevent maximum depth unless you are very careful what you expose the coil to during the procedure, hence the time frame of the forced GB section. With that in mind I always have the GB speed set on Medium then after getting in the ball park let the GB go through the forced period into Tracking speed mode for the final result.
JP

"Only if you keep the button depressed longer than the forced GB time frame"
Are you talking about being in fixed or tracking?
I'm talking about being in fixed, and thought there was no time frame when bobbing it in fixed with the button depressed?....ie ( no chirp mode )


AFAIK Forced is still in effect even when in FIXED, so if the button is held for long enough you will revert to the underlying GB speed selected under the GB menu.
JP

Hope this helps because if its not rectified like i have seen many do out in the field, you could be blaming your detector for your misunderstandings.
The 4500 is a pretty forgiving detector in many of its audio and motion filters using enhance, but the GB is another animal.
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Re: Timing question on 4500

Post  marty on Tue Dec 21, 2010 2:45 pm

Thanks heaps for that Narrawa,when i ground balance, from the time i hold the button down to the time i let it go is about 7 sec.The manual says the quicktrac goes for about 3 sec or a very short time so i must be going through the quicktrack and into the set medium tracking ! Then when i change to fast tracking it does the same but goes into fast tracking.Last night i did the same test again but this time it was a quiet piece of rubbish and again it was slightly louder on the fast tracking?There's not alot of difference but it's definatly noticable.What i can't understand is that if the machine is ground balanced at 2 different speeds on the same spot why do i get a different result when i swing across to the target right next to it. I thought ground balanced was ground balanced no matter what speed you do it in? Can i ask how you ground balance in fixed or anyone else. Thanks agian for your help. MARTY

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Re: Timing question on 4500

Post  Narrawa on Tue Dec 21, 2010 4:06 pm

Marty, the main thing to remember after you have done your GB is to let it settle for about 2-3 seconds after releasing the green button before moving the coil.
Select tracking speed.
hold button down.
bob the coil (i bob reasonably quick) from ground to about 4"
finish with coil on the ground, release button wait 2-3sec then move on.
The only time this procedure gives me a hassle, is if the ground is really hot. (ironstone) I then may have to keep the coil just off the ground on settling.
What i can't understand is that if the machine is ground balanced at 2 different speeds on the same spot why do i get a different result when i swing across to the target right next to it.
As for this, m8 i dont know to be honest, there could be many reasons, one could be if you dont let the GB settle?? From the time you let your finger off the green button, the detector now has to register the off signal and revert back to fixed.??
Remember it says 3 sec to carry out the forced GB, it may require a small off period to settle. (works for me)Laughing And most of us would hold the button down when doing a GB for about 5-7 sec overriding the forced GB anyway.
I'll go out on a limb here and say from my experiences the 4500 will 1 out of 3 attempts fail to GB, and i put that down to operator fault. Gain to high is one that i have found over to hot a ground.
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Re: Timing question on 4500

Post  davsgold on Tue Dec 21, 2010 5:33 pm

G'day Marty

Narrawa is right when he says getting the ground balance right is critical. Marty when you say you get 2 different results, you can probably get a lot more different results if you want depending on the way you ground balance the machine.

Have the front switch in fixed position, have the rear menu screen set on medium, this is a good all round detecting setup. Then ground balance by depressing and HOLD the green button while rasing and lowering (bob the coil up and down) from about ground height to 2" to 3" above the ground, keeping the coil parellel to the ground while doing so. Then when ground balance is acheived ( no variation in sound while raising and lowering coil) hold the coil still at ground level or at the level you are going to detect at and release the green button. Hold the coil still in this postition for the 2 to 3 seconds and then begin normal detecting, or swing over the target and check the signal again.

cheers dave
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Re: Timing question on 4500

Post  marty on Tue Dec 21, 2010 6:29 pm

Thanks Dave,i will really focus on my ground balancing now one thing i havn't been doing is holding the coil still for 2 or 3 secs at the end, so i will give that a go. cheers sunny MARTY

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Re: Timing question on 4500

Post  marty on Tue Dec 21, 2010 6:53 pm

Hi again Narrawa,thanks for all that info mate,the spot i've been working is pretty noisy red clay and i find i'm balancing nearly every 4 or 5 steps and i havn't been holding the coil still at the end of ground balancing to let it settle.Im pretty sure theres more nugs hiding in the deep clay.Another little run about 30 m away is producing really nice short quiet signals every 1 or 2 m (did my head in) all ground noises,i'll have to work on different settings there i think. Thanks MARTY

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Re: Timing question on 4500

Post  Narrawa on Wed Dec 22, 2010 1:07 am

marty wrote:Hi again Narrawa,thanks for all that info mate,the spot i've been working is pretty noisy red clay and i find i'm balancing nearly every 4 or 5 steps and i havn't been holding the coil still at the end of ground balancing to let it settle.Im pretty sure theres more nugs hiding in the deep clay.Another little run about 30 m away is producing really nice short quiet signals every 1 or 2 m (did my head in) all ground noises,i'll have to work on different settings there i think. Thanks MARTY
Not sure what size coil your using, but the use of smaller coils, 14x7-9 to 11" and below, can have trouble GBing on noisy ground due to their more concentrated fields. Another reason is that smallish coils take a much smaller snapshot of the ground for the GB to average compared to larger coils, and this is probably the reason you find yourself GBing every few feet.
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Re: Timing question on 4500

Post  Guest on Wed Dec 22, 2010 8:15 am

G'day Marty,

Are you paying attention to your autotune or manul tune before you ground balance?

Robert

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Re: Timing question on 4500

Post  marty on Wed Dec 22, 2010 12:20 pm

Hello Robert, i really only autotune at the start then try tweaking either way no more than about 5 clicks,if i'm not happy with that i'll try again.Sometimes it gets noisy a few hours later so ill do it again but thats about it. Doing it in fixed with gain at about 15 seems to help. Sometimes the EMI is pretty bad out there with big power lines and a minesite very close by.After that i don't look at it and just try to work with the interferance.Does this affect ground balance?

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Re: Timing question on 4500

Post  marty on Wed Dec 22, 2010 2:33 pm

G-Day Narrawa, i think your spot on there again mate.I use a 16' mono NF Advantage and an 8' mono comander and come to think of it i can go alot further with the 16' over the same ground as compared to the 8' before i have to re-ground balance.One of the main problems i have with both coils is once i get a signal with the detector running bearable to the ground and EMI, i scrape the thin crusty surface to expose the red soft puffy clay,run the coil over it to listen to a howl over the sraped area and the dirt flicked out from one end to the other.The last week or so we've had some rain and a drop in temperature to the low 30's, so im presuming the ground has cooled making it workable with a mono(and the 4500 and it's settings of corse).Now it's going to heat up to a forcast 44 deg Christmas day so i'll have to give it away till the next lot of rain or winter. I can run the 45 in Quiet but i'm pretty sure i'm loosing too much sensitivity so i might be better off waiting. But no doubt it will get the better of me and i will be out there at 3.00 am staggerin around in the dark. cheers MARTY

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Re: Timing question on 4500

Post  davsgold on Wed Dec 22, 2010 4:01 pm

G'day Marty

You seem to be having a lot more noise than should be expected. Wet ground will give more ground noise than dry ground. Hot ground as in heat from the day will also give more ground noise. During summer detecting in the evining and early mornings should overcome this problem a fair bit.

Some switch positions on the front of the detector will have a major bearing on how noisy the machine runs. There has been a good discussion on ground balancing and wether to run tracking of fixed. Also the coil/rx switch can be in either DD or mono position when using a mono coil, you won't notice a great deal of difference at this stage.

Check the position of these switches........

On the front of your detector, where are you running the search mode switch (first switch) there are 3 choices custom, G & deep.

The soil timing switch (second switch) also has three positions, where are you running it, there are 3 choices enhance, normal & special.

Using a mono coil in noisy ground ie: ironstone and red clay etc etc use enhance position and fixed ground balance position, and search mode switch in G position.

cheers dave
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Re: Timing question on 4500

Post  marty on Wed Dec 22, 2010 5:21 pm

Hi Dave,i run the front pretty much how you said then muck around with back.This is what i sort of end up working with using the 16 and 8 inch monos. FRONT ~ general . enhance . fixed . mono
REAR V/LIMIT 12
GB/TYPE general
MAN/TUNE ( 8' 190 -250) ( 16' nearly 250 every time )
MOTION v/slow
GAIN (8' 7-11) (16' 8-9)
AUDIO (8' boost) (16' deep)
AUDIO/T (8' 45) (16' 40)
STAB (8' 6-10) (16' 6-Cool
SIG 14 - 19
TARG VOL 13 - 15
RESP normal
TRACKING med or fast
Every trip i go on i record the settings and other details so can hopefully get my head around it all. Im unsure about the order of taming the detector down using individual functions etc. to prevent me unesesarily dumbing the machine down to a level where i miss targets!(bit paranoid about that) I originally hammered the place with DD's on my old GP Extreme encountering interference and ground noise but still found gold.Any advice you could offer Dave would be great. Thanks MARTY

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Re: Timing question on 4500

Post  davsgold on Wed Dec 22, 2010 7:34 pm

G'day Marty

Alot of the setting you are using are very similar to mine for most of the conditions I encounter. I do use a twin speaker system and booster that is indepenant of the Minelab battery booster, which is still very good by the way. I don't like headphones.

So the couple of differences the my settings are compared to yours REAR V/LIMIT 12 mine is 10 ........yoursTARG VOL 13 - 15 mine is 8 for booster with speakers of 12 for headphones........yours SIG 14 - 19
mine is mostly 19

I mostly just manual tune and I find that somewhere around 100 to 112 usually dose the trick.

cheers dave



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Re: Timing question on 4500

Post  marty on Wed Dec 22, 2010 8:13 pm

Dave thanks mate for that, do you think my auto tune of around 250 is a bit odd or high? It comes up at that nearly every time in that spot? MARTY

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Re: Timing question on 4500

Post  davsgold on Wed Dec 22, 2010 9:03 pm

Marty it does seem high for some reason, thats why I prefer to just manual tune, and usually I only have to go a few numbers either way of where i like it if a bit of EMI interference starts comin through. Start at 128 thats half way and go down from there till it gets quiet.

Don't confuse EMI interference with ground noise, hopefuly you know the difference.

Also a couple of other settings to check, in the rear menu screen I have the motion setting on slow, go to very slow setting if it is getting to noisy. I like to the audio in boost for smaller coils (8" or 11" Mono) like you mentioned and deep audio when using bigger coils (16" mono).

If the RX gain is on about 9 then I have the stabalizer on about 8 and if I can get the RX gain to 12 or 13 then I take the stabalizer back to about 6

More RX gain = more noise so back of the stabalizer a bit to compensate, if you get the stabalizer way low like 2 to 3 it will quieten the machine down a lot but you need to swing REALLY slow to compensate for these real low stabalizer numbers.

cheers dave
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Re: Timing question on 4500

Post  marty on Wed Dec 22, 2010 10:43 pm

Thanks Dave i"ll have a good go at all of that. Very much appreciated. MARTY

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