REVIER
Well-known member
I have been trying to absorb all I can to use my F70 at optimum levels.
There is a lot of info I took off of Nasa Tom's site and posted in that thread about 2F tones...here is some more.
Except for the LCD bar graph thing all of this will also pertain to the F70...
This one is about using the F1-F7 frequency settings.
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A topic well worth revisiting. [size=large]F1 - F7 EMI mitigation[/size].
I know I have touched on this topic before......but now, I have much more amplifying information. I know I should utilize a U.S. $1 Type-1 gold coin.....as this is the perfect resonance (pinnacle performance) of the F75/LTD......yet, I used a common clad dime for better audience understanding.
Taking a U.S. clad dime to a area that presents near perfect conditions for testing. Here is the importance of Freq Shift (F1 - F7) .... so as to achieve maximum performance. At a local park, , , burying the dime @12"......in sanatized dirt........and virtually no EMI presence......the F75 will (just barely) detect this dime. Changing the frequency from F1 through F7........no EMI change of status (no audible EMI present on any channel).......... and also no change in performance of 12" dime detection with F75 LTD. The CZ-3D will also detect this dime with zero problems.
Moving 75-feet away from this location......where EMI is "moderate"......and a huge (and measureable) delta occurs. With the dime buried at only 8"...... a dramatic incursion ensued. Selecting the BEST frequency that provides the least EMI......and this dime can be detected with ease......AND this is to include over half-a-foot of air-gap over the ground. Yes.....this is to say that the coil is 6"-plus inches above the ground PLUS the 8" that the dime is buried. A total of 14"-plus inches between coil and dime.
Now........Selecting a different frequency that provides/presents a noticable amount of EMI (and this is NOT the worst channel/freq selection; rather, a 'middle-of-the-road' selection).......and the detection of this 8" dime is COMPLETELY undetectable. Here...........The CZ-3D still poses extreme audible stability.........absolutely no idea there is any form of EMI what-so-ever....BUT, BUT, BUT......the CZ will only detect this dime to 10". This is categorized as the most dangerous type of (electronic related) hunting......because the operator has ABSOLUTELY NO IDEA the unit is operating at a reduced performance level. Unsuspected and undetected/unknowing reduced performance. The operator would NEVER know it; subsequently, never suspect any form of performance reduction.
[size=large]THE BEST WAY TO REDUCE EMI:[/size]
Place F75 in all-metal mode with max Sens ('99'). Hold coil about a foot above the ground.....very still......and perfectly parallel with the ground. Select F1 through F7.........one at a time...... and listen to each channel/freq for about 4-5 seconds. Find the one freq/channel that provides the least interference. Now you can switch back over to the ID mode......and.....yes......this Freq/channel selection will stay the same whilst switching over to the ID mode. If you are running the unit 'wide open'....and you still are encountering EMI..... you can change Disc to a setting of '5'. There is a huge difference between Disc '4'....and Disc '5'. You should not have to increase Disc to higher numbers. If EMI is still present.... you now can start to drop Sens .... until EMI is gone. Remember; you are already on the best possible F1 through F7 Freq/channel selection...and must employ other methods so as to reduce EMI... if it is still present.
If you look at your LCD depth bar-graph......and EMI is causing it to jump all the way into the middle bar-graph (medium strength signal) ............you will only be able to detect targets that are (at least) as strong/powerful.....OR STRONGER (shallower) as that middle bar-graph. This is also to say that......if you want to get rid of audible EMI......you would then be required to reduce Sensitivity to the point where targets in that middle bar-graph (and deeper targets)... would no longer be detected. What you are doing is.....reducing the sensitivity of the detector to 'just below' the signal strength of the EMI. Said differently; If EMI is so strong......that this specific EMI "looks like" a 7" deep target................then the detector will only be capable of detecting targets up to 7" deep....and no deeper... in this hunting area.
Some of the best days to hunt.....as far as EMI is concerned......is at the very end of a hard rain........or shortly after a hard rain......as this is what washes the salts off of nearby powerlines.
If you are 'beating' an old/hunted-out area again.......and you suddenly learn that you are finding a lot more targets........it may very well be that you are encountering less EMI on this specific day.
I can only stress the level of importance of EMI mitigation. USE THAT F1 THROUGH F7 OPTION.
There is a lot of info I took off of Nasa Tom's site and posted in that thread about 2F tones...here is some more.
Except for the LCD bar graph thing all of this will also pertain to the F70...
This one is about using the F1-F7 frequency settings.
--------------------------------------------------------------------------------------------------------------------------------------
A topic well worth revisiting. [size=large]F1 - F7 EMI mitigation[/size].
I know I have touched on this topic before......but now, I have much more amplifying information. I know I should utilize a U.S. $1 Type-1 gold coin.....as this is the perfect resonance (pinnacle performance) of the F75/LTD......yet, I used a common clad dime for better audience understanding.
Taking a U.S. clad dime to a area that presents near perfect conditions for testing. Here is the importance of Freq Shift (F1 - F7) .... so as to achieve maximum performance. At a local park, , , burying the dime @12"......in sanatized dirt........and virtually no EMI presence......the F75 will (just barely) detect this dime. Changing the frequency from F1 through F7........no EMI change of status (no audible EMI present on any channel).......... and also no change in performance of 12" dime detection with F75 LTD. The CZ-3D will also detect this dime with zero problems.
Moving 75-feet away from this location......where EMI is "moderate"......and a huge (and measureable) delta occurs. With the dime buried at only 8"...... a dramatic incursion ensued. Selecting the BEST frequency that provides the least EMI......and this dime can be detected with ease......AND this is to include over half-a-foot of air-gap over the ground. Yes.....this is to say that the coil is 6"-plus inches above the ground PLUS the 8" that the dime is buried. A total of 14"-plus inches between coil and dime.
Now........Selecting a different frequency that provides/presents a noticable amount of EMI (and this is NOT the worst channel/freq selection; rather, a 'middle-of-the-road' selection).......and the detection of this 8" dime is COMPLETELY undetectable. Here...........The CZ-3D still poses extreme audible stability.........absolutely no idea there is any form of EMI what-so-ever....BUT, BUT, BUT......the CZ will only detect this dime to 10". This is categorized as the most dangerous type of (electronic related) hunting......because the operator has ABSOLUTELY NO IDEA the unit is operating at a reduced performance level. Unsuspected and undetected/unknowing reduced performance. The operator would NEVER know it; subsequently, never suspect any form of performance reduction.
[size=large]THE BEST WAY TO REDUCE EMI:[/size]
Place F75 in all-metal mode with max Sens ('99'). Hold coil about a foot above the ground.....very still......and perfectly parallel with the ground. Select F1 through F7.........one at a time...... and listen to each channel/freq for about 4-5 seconds. Find the one freq/channel that provides the least interference. Now you can switch back over to the ID mode......and.....yes......this Freq/channel selection will stay the same whilst switching over to the ID mode. If you are running the unit 'wide open'....and you still are encountering EMI..... you can change Disc to a setting of '5'. There is a huge difference between Disc '4'....and Disc '5'. You should not have to increase Disc to higher numbers. If EMI is still present.... you now can start to drop Sens .... until EMI is gone. Remember; you are already on the best possible F1 through F7 Freq/channel selection...and must employ other methods so as to reduce EMI... if it is still present.
If you look at your LCD depth bar-graph......and EMI is causing it to jump all the way into the middle bar-graph (medium strength signal) ............you will only be able to detect targets that are (at least) as strong/powerful.....OR STRONGER (shallower) as that middle bar-graph. This is also to say that......if you want to get rid of audible EMI......you would then be required to reduce Sensitivity to the point where targets in that middle bar-graph (and deeper targets)... would no longer be detected. What you are doing is.....reducing the sensitivity of the detector to 'just below' the signal strength of the EMI. Said differently; If EMI is so strong......that this specific EMI "looks like" a 7" deep target................then the detector will only be capable of detecting targets up to 7" deep....and no deeper... in this hunting area.
Some of the best days to hunt.....as far as EMI is concerned......is at the very end of a hard rain........or shortly after a hard rain......as this is what washes the salts off of nearby powerlines.
If you are 'beating' an old/hunted-out area again.......and you suddenly learn that you are finding a lot more targets........it may very well be that you are encountering less EMI on this specific day.
I can only stress the level of importance of EMI mitigation. USE THAT F1 THROUGH F7 OPTION.
