F-75 lower Disc ¿?¿?

Can anybody explain to me what would happen if I lower my disc to 5 or less on my F75?
Now i search with disc at 10, and I´m still pulling out some medium to big pieces of iron, like horse shoes and similar.
If I lower it to 5 will I go crazy?
This questions come up because I´m going to search in a roman area, and I dont want to miss the real small roman coins and artifacts.

Thanks for the help.

Also THANKS to Nasa Tom, I downloaded all your reading material and have gone through it several times.
I hope to go to the beach with the F75 for the untouched micro jewelry...

Cheers from Spain

Hello Nutriasub, I run my f-75 at 0 disc with sensitivity at max and 4 tone. Yes, it will drive some crazy but I want to hear what I'm walking over. Gives me a better feel of the area I'm hunting. It didn't take me long to get use to all the chatter, but the chatter is usually all the bits of metal in the ground. The f-75 will detect just about everything, thats how fast it is. Every so often when there is EMI, I will up the disc or try the freq shift, last resort I lower sens which I don't like doing.
I want my detector to run at it's peak performance and I believe those settings are the best for the f- 75 in my area of Pennsylvania. Less than 5 disc is the key number on the 75. For me, why bother, just drop it to zero. There are many wright-ups about this in Tom's forum, search it out. Tom has done extensive tests with the 75, follow his advise..you can't go wrong. I also want to say I hunt in areas with a lot of iron bits and pieces of nails, rust, you name it. When I use any discrim, it seems to creat more unnecessary half pops, crackles and iffy signals, which I don't like to hear. The discrimination of the f-75, in my opinion, isn't the best, certainly not as good as the E-trac or Explorers. The speed and seperation of the f-75 is what I can't live without. Welcome to the forum.

Time permitting.........read the threads titled:

COMPILATION #1
COMPILATION #2
Rcpt Ack of F75 Ltd Proto

This 'should' help a bunch.

Tom, can you make those threads a 'sticky' and keep them permanently at the top of the forum?

Not a bad idea. ......Wally???

Picked this up somewhere, help me understand low DISC being unstable.

F75 going crazy ? Read this :

The number one problem seems to be that the F75 can go crazy and beeps constantly and the VDI numbers jump all over the place.
Well....that happened to me and my F75 too.
Nothing was wrong with the detector. You just have to know that the F75 picks up sources of interference in the high gain modes.

Next you need to know what are the high gain modes.

1. High gain in DE mode kicks in if you have the disc lower than 5 or higher than 19.

2. The JE mode is a total high gain mode no matter what disc setting you use.

In a perfect world the JE mode with a high sensitivity setting would get us the best depth. Or the DE mode with the disc lower than 5 or higher than 19.

Now how do you find out if you have interference sources nearby ?
Turn on the F75 with a sensitivity setting of about 70 and lift the coil to waist level. Now select JE mode, or DE mode with the disc lower than 5. If the F75 goes crazy an interference source is picked up by the F75.

Now how do you get the F75 stable ?
1. Select DE mode AND disc between 5 and 19. Sensitivity as high as possible without falsing.


Next problems seems to be chatter from the ground.
1. Make sure with the steps above that your ground noise is not interference.
2. GB the detector using fast-grab.
3. Go to manual GB and set the number that fast grab found 1 to 3 numbers to the positive side. So if fast grab was 60 set the manual GB to 61 to 63. That way the detector will have a positive GB offset and not give a signal to smallest changes in the ground.

A cellphone, even on standby, is a huge interference source !!!! Turn it off !!!

Last week i a got a call from Ralph at Sun Ray Electronics, who brought other good information to my attention about the F75 and chattering.
I have to say that i never used notch on the F75 before (just disc) but after playing with notch and disc i was able to reproduce what Ralph talked about.
Here is some examples what can happen if you use notch and disc:
1. If you set DISC to 0 and use Notch to cancel out target group 1 to 7 you still have accepted 0 and that causes the detector to be unstable.
2. If you have DISC set anywhere from 1 to 7 and up and you go to notch and select any number from 1 to 7 you have NOT notched out the numbers, you have notched them back in (accepted them), because Notch does the opposite from the current disc setting. That will cause the detector to be unstable again, because accepted numbers from 0 to 5 run a higher preamp gain.
3. If you think you have messed up your Disc/Notch settings do a factory reset by turning the detector off and then push the trigger forward and press menu button while turning the detector back on.
I hope that will help some guys not to have to send the detector in for repair for something that is not broken.
Thanks Ralph for the input,
Andy,NM

F75 FAQ's :
Q 1. : Why is only one rubber washer for the lower stem in the box ? Is one missing ?

A: The F75 comes with only one rubber washer, because that's all you need. If you feel you need a second one contact the factory at: 915-225-0333
I bet they will be happy to send you a second one.

Q 2. What are the best settings to start with ?

A: When you start the F75 up the first time it starts in DE processing, Disc at 10 and sensitivity at 60. I found it to be a perfect setup to start with. Before you change anything make sure you get a feel for the detector with the above settings.

Q 3. After I ground balanced the detector with fastgrab it can't find a coin on the surface. Why is that ?

A: Make sure you don't see the words " can't GB" on the display while pumping the coil up and down over the ground.If that happens the detectors performance is close to zero after you release the trigger.

Q 4. The detector seems to pick up ground noice after ground balancing with fastgrab. What is wrong ?

A: When using fast-grab the detectors seems to be right on with the ground balance. It is so good that after ground balancing every tiny change in the ground matrix is seen as a target. I use fast-grab first and then change to manual ground balance and GB the detector plus 3 numbers. So if fastgrab was 70 I set it to 73 (positive offset). That way the detector doesn't see very small changes in the ground matrix as a target anymore. 3 numbers plus is about what a 1/8 turn on a 4 turn tesoro ground balance would be.

Q 5. I can't find the warranty card in the box of the F75. How can i make sure i get warranty service ?

A: Just keep you receipt from the dealer who sold it to you. You have 5 years warranty from the day you bought it. I taped the receipt in the F75 box to make sure it won't get lost.

Q 6. What are the hottest setting for the F75 ?

A: What sensitivity and modes can be used are controlled by the ground conditions and location (interference free or not).
I always start in the DE mode, Disc 10, sensitivity 50.
If you can push sensitivity high in that mode, it is an indication that you may be able to use the JE mode. But before you switch over to the JE mode make sure to lower the sensitivity. Because you can run sensitivity at 90 in DE mode doesn't mean you can run that same sensitivity in JE mode. On the other hand sensitivity at 60 in JE mode can be deeper than sens at 90 in DE mode. Some locations may not allow to use JE mode but DE mode could work just fine.
The target is to run as much sensitivity as possible while remain a very stable detector. That balance changes with ground condition and location.

Q 7. I can't get the F75 to work at the beach. Do you have some beach settings ?

A: First you need to know that most beaches ground balance under 40. That means you can NOT use fastgrab. You have to use manual GB to balance to ground under 40.
To avoid reflections from the salt use the DE mode and lower the sensitivity (Not JE mode because the gain is to high for salty ground).

Q 8. Even in DE mode the F75 is very unstable and noisy. Why is that ?

A: If you set the Disc lower than 5 or higher than 19 the detector runs at a higher gain in DE processing. That higher gain means more depth in interference free and mild ground areas but if interference or bad ground is present the detector becomes noisy and unstable.
For best stability run disc between 5 and 19 in DE mode. Reduce sensitivity too if needed.
The JE processing mode has a much higher preamp gain than the DE mode and is very sensitive to interference sources like cellphones, lightbulbs, power lines. If the detector goes crazy in that mode go back to DE mode and set Disc between 5 and 19.

q



Edited 1 time(s). Last edit at 01/11/2011 10:53PM by Shooter.

.......and with the advent of the F75 LTD/Special/Black.......the 'bp' mode is the trump card......even over the 'je' mode.

Interesting read.

I tried yesterday the "top performance" for the F75, with disc 6, sens 99 and monotone.

I´m pretty used to the 2F tones, so going back to the monotone was kind of weird, no everything sounded OK. I was in a nails infested area, and I dug 6 o 7 nails before going a little crazy with so many targets.
I think one of my problems its that I only look at the VDI when the sound its good, so if its at monotone I will be looking at the VDI all the time.

After a little while I must admit that it was too much for me and went back to 2F, disc 10, sens 90 (couldn't go any higher, to much chatter)

I found some good stuff, although I heard all the chatter too from a lot of the iron that VDI as 8-9.

I´m going back this week to an old site, I´m going to try the top performance set-up again and be patient with it.

Thanks for the help you all.

I am TRYING to find time to write another article....on just exactly this...... but SOOOO busy with this web-site (which is on fire....as of lately). Hope to have the article up on the home-page soon. In the meantime......if you can read the threads titled:

COMPILATION #1
COMPILATION #2
Rcpt Ack of F75 LTD Prototype

.......these should help.

Tom:

i re-read the comp 1, and my only doubt is when you have disc at 6, do you dig all of the jumpy signals? if its a solid signal, even at lets say 13, do you dig it? I would think its iron.

When you say that the sound its like a machine gun, and the VDI also goes back and forth, does this mean that there are several targets, or its just iron?

thanks a bunch for all you time and efforts

A few things worth repeating:

When in MONOTONE and Disc '6'........there is a judgement call........and it is determined by your ears. First IGNORE the VDI numbers! Listen to the audio response. Yes, you will dig a lot of nails (at first). There is a learning curve. You will (fairly soon) begin to audibly recognize what IS a good tone....and what is NOT a good tone. Also......you may find that your nails are at a different decomposition status; subsequently requiring a Disc of '7'......or maybe a Disc of '5' for your specific site. It is VERY important to determine this at the BEGINNING of the hunt.......prior to allowing 'burn-out' and/or 'fatigue'. There are GOING to be 'some' iron targets that will be above a Disc '6' setting; usually axes, hammers, files, cannon balls, gun barrels........you get the point!

Now.......machine gun audio is normally refered to Disc '0' and a multi-tone selection. This ALSO requires your ears and brain to ignore (before fatigue) of all the low iron tones in many areas the we like to hunt. Most of the areas we like to hunt are littered with iron.....and the detector may be continuously reporting audio responses. Most of the areas I hunt......there are nearly ALWAYS multiple targets under the coil.....at any given time.

Tom,

Just had a quick question. Is there any benefit to using 0 disc vs 6 disc or 4 disc if you are in 2 tone besides extra sensitivity. Does it help to unmask? I am trying to relate this to T2, I have been using a disc setting of 21 in 2 tone, should I be using 10 or below, especially if there is no dense iron requiring 21disc and 1+ tone setup to unmask.

Similar question using the F75 LTD... Any performance difference coin hunting between, say, DISC=0/SENS=70 vs DISC=6/SENS=80, to yield equivalent sensitivity on a coin? It seemed to me that DISC=0 yields the cleanest audio, but I might be imaging that.

Any takers?

Well, I had a T2 and now the Omega and have played around a ton with discrimination. I didn't do any tests per say though. I always ran/run my detector with no discrimination if the ground would allow. That is easier on the Omega than the T2 because of two reasons: it runs quieter and the iron volume is lower so there is no audio fatigue.

I would say thought that running less discrimination would always be my choice if possible. Also, there is the question of EMI that has been spoken about recently. I think it will come down to site and it's individual conditions. This is where a test garden would really help. If not, find a deep or soundingly masked target with no discrimination and compare it with some disc to see which one receives the target better or if there is any effect.

But Idream, if you don't have dense iron you can only be hurting yourself by running extra discrimination. Also, isn't there the "boost" mode to consider with disc at 51 on the T2? Worth a test. I really don't know if there will be much masking at disc of 6 or 4 vs 0. Is there another boost at disc 0?

IRT F75:

A Disc setting of '6' is strictly reserved for monotone. The intent here is to unmask all non-ferrous targets in nail infested sites. In carpets of nails......your max depth is going to be severely hindered anyway.......so.......a Disc of '6' is not what will be the depth inhibiting factor; rather, all of the masking from the nails will hinder overall/final depth.
If you are hunting in any form of multi-tone options (ie.....2-tone, 3, 3H, 4, 4H tones).......and ESPECIALLY if targets (good or bad) are sparce......this is where max depth can be achieved with regular frequency; subsequently, a Disc of '4' and less......is highly preferred. Disc '4' is the magic number whereby a formidable amount of depth is ascertained (restored). When you are in a multi-tone option....you are not so much concerned about "Disc'ing out" targets..........because it is now the TONES that will do this for you..........rather, you are more concerned about GREATER depth with tones being utilized for HUMAN ear discrimination.

And finally; YES. In mineralized dirt.....and/or a partial masking scenario................a lower Disc setting WILL give better audible presentation/intelligence on a coin (and other targets) whilst in a multi-tone selection. On many occasions, I have witnessed up to 50% degradation of audio report of a high conductor coin.....simply by changing Disc from say '2'.......up to a Disc of '6'. Even though these lower Disc settings are substantially BELOW where a coin would Disc out.....it still affected the audio detection report.

Thanks Tom, and Keith mentioned the same thing to me as well, no wonder I had such mixed results with the T2, digging lots of ghost signals and the signals usually sounded pretty degraded in 2+, and especially in 3&4 tone. That was probably because I was running my disc at 21 all the time. Now I going to run it at 10 or bellow, and use the sensitivity setting to mitigate the EMI. Really looking forward to trying it out when the weather warms up.