F-75 interference isolation

Not wanting to believe the interference problems w/F-75 are non-isolable... today, I hunted at a active airport approx 900yds from surface-to-air rotating radar,,,,,, and also approx. 700yds from Florida's largest cell-phone tower. Zero interference encountered. In fact, (for the very first time outdoors), I was capable of maximum overdrive with F-75. Sens '99', Disc '00', "JE" mode, '1' tone (sometimes 4H tone) and nothing 'notched'......and ascertained zero interference. Complete stability. It is really looking like interference issues are electrostatic (mother nature) or.... MOST likely electromagnetic (power lines) induced. I am heavily leaning towards the latter. Today, in this particular area,,,,,,this F-75 set-up config was too hot....as the area was Fe nail infested..... so I defaulted to "PF" mode, Disc '06', Sens '99' and monotone. In a 35' x 60' area, I recovered 77 non-ferrous targets that the T-2 never found...(( Head-to-Head validated )). Stupendous performance. ... Would like to replicate/duplicate this 'zero interference' condition more frequently....at other locations; hence, authorizing F-75 overdrive capabilities.

Tom

Hi Tom,

I just posted a message to you under T2/F75, when I noticed your post on F75 interference isolation. With both my first and second F75's I have experience increased interference when the discrimination is increased.

I would be interesting to know if what you noted in you post is also true when discrimination to set to 65.

Thanks, Bill

Specifically "60HZ" AC may not necessarily be the culprit; HOWEVER, a dirty connection (or wet lines) where there is voltage leakage (sure,,, it'll be in a 60Hz fashion)....seems to be a strong candidate thus far.

Tom

Hi Tom,

I tried a very dirty 60Hz source within 1 to 2 feet of the detector without any noted interference. There may not be one interference problem.

I have talked to a number of F75 users, and there seems to be no set pattern to the interference with respect to location.

If the interference is one source then shielding or simple notch filters would correct or fix the problem. I hope you figure it out. Does First Texas have any ideas?

Thanks again, Bill

Except from me..... First Texas is "unaware" of any interference problems.

Hi Tom,

Me too! I was the first person to send a F75 back the the factory! There is a problem, and I hope they seriously try to determine the source of the interference.

I am going to try to find the source or sources. I will keep you posted.

Thanks, Bill

Hi Tom,

I have included some post from findmall.com that I think you might find interesting.

Post below:


Quote:
Tagamet
I too, really like the F75. Unfortunately, mine went absolutely GOOFY on me, so it had to be returned for "repair or replacement". They did require a Return Authorization and sent UPS to pick up the machine. Since I'm in Penna and the factory is in Tx, it's been over a week and it still hasn't arrived at the factory. It's CLOSE though (in New Mexico) and is scheduled for delivery to them today. I don't think that I'm alone in feeling like time away from a machine passes in "Dog Years" (lol). My hope is that they look at it and send me a new machine. My fear is that they'll return it with a note saying that they can find nothing wrong with it. The dealer from which I purchased the unit has been very supportive (name withheld to protect the innocent), but he is also new to dealing with First Texas.
So I guess the bottom line regarding customer support from First Texas for me personally is that the verdict will be rendered soon. I'm a firm believer that good customer support should be praised from the rooftops. On the other hand, if a company wants to "take the money and run", that needs to be reported too. I'll definitely be reporting back as soon as I hear.
Thanks,
Tagamet

Quote:
BTaylor
Hi Tagamet,
What do mean the detector went absolutely goofy?
Thanks, Bill

The numbers and the sounds were all over the map and sounded "scratchy" as opposed to tones. Also it wouldn't react to obvious targets like a 30.06 laying on the ground. Yes, I tried resetting everything back to defaults, hi sens, low sens, hi discrim, lo discrim, ALL the frequencies, 3 different sets of head phones, changing the site to rule out electrical interference, Fast grab GBing, manual GBing +5, You name it, I systematically and exhaustively, tried to eliminate it. I even took the coil cover off and washed the coil. No luck. I'm hoping that it was just some quirky thing that they (and hopefully I) can't replicate. It's possible that it's the coil, and they'll replace it, if it continues to act goofy, but they couldn't get that coil to misbehave in Texas.
Actions speak louder than words, so if they had just rushed it out the door "because we knew you were anxious to get it back" that'd be one thing. But they rushed it back by 2nd day AIR, which says volumes (to me anyway). That they'll replace the coil if need be, is also a major indication. And that the President of the company was aware of my situation and bothered to call ME says something, too.
I'll know SOMETHING more tomorrow, because I'll be meeting the UPS truck with the Jeep idling in the driveway.
I'll post more soon.
Tagamet


I had a great conversation with the president of Fisher today. He'd spoke to Brian at @#$%& yesterday and had Brian ask me to call him. We went over all the variables and adjustments I'd tried with my F75 prior to my returning the machine for service. He was genuinely interested in what might have been going on, because they had been unable to get the machine to behave poorly. Since he and I couldn't make a phone connection yesterday and he was aware of how anxious I was to get a functioning machine back in my hands, he'd gone ahead and shipped my F75 late yesterday BY 2ND DAY AIR. It'll get here tomorrow! Although they had tested my machine with the same coil I'd had, he did think that that might be one variable that may have been just quirky enough to make a difference across settings (as in geography - TX vs PA). He asked that I try it out, and if I'm still getting irratic behavior from the machine to call HIM and he'll trade out the coil to see if that's the problem.
The bottom line is that whoever posted on here that "Fisher wants to get it RIGHT" was 100% accurate. If it was a publically trade stock, I'd buy it (it's not, I checked).
These days, it's really neat to FIND a company that's sensitive to it's customer's needs and is willing to go the extra mile to meet those needs. It just makes sense to support those companies.
Thanks Fisher,
Tagamet


Quote:
Andy,NM
Because some problems could be related to settings used or location.
I found myself accidently notching in iron, because if you have disced out iron and then press the notch for iron you have it back-notched in.
The other thing is if you have disc set below 5 in de mode or disc higher than 20 in de mode the detector can become unstable if a interference source is close.
Andy,NM

I'd like to know what was wrong too. The symptoms remained the same across three different sites, including my "learning" site - a set of soccer fields out in the middle of nowhere, with minimal trash and plenty of clad laying shallow, a hunting camp out in a forest that DID have a transformer on a pole overhead, and another mountain site with no electrical wiring within MILES. I tried all frequencies. Repeated Fastgrab GBing (and watching closely for those tiny "Can't gb" words), resetting to defaults, using high discrim, low discrim, low sensitivity, etc. You name it, I think I tried it. Believe me, I REALLY didn't want to send the machine back to Tx! I've NEVER returned a machine before. The best I got was a barage of chatter, with ID numbers that jump all over the place, with some scratchy noises posing as "tones" that were really difficult to pull from the background chatter. Shouldn't resetting to defaults have fixed these issues given the different places I'd hunted?
Thanks,
Tagamet

Once again Fisher not able to find the problem?

Thanks, Bill

THANKS for the update..... as I did not catch all of these!

Tom

the following is the reply i got from fisher, what do you think?? -----Original Message-----
From: John Griffin
Sent: Tuesday, May 29, 2007 10:37 AM
To: Fisher Research Customer Service
Subject: RE: Industrial Section Feedback from charles graves

There are no electrical interference problems with the detector. What
actually happens is the F75 is so sensitive that the sensitivity
setting must be adjusted given it surroundings. We actually started
including the attachement below in the new units so people would understand to
help folks with its operation.


ELECTRICAL INTERFERENCE
The Fisher F75 is probably the most sensitive metal detector ever
manufactured.
Such high sensitivity makes the F75 susceptible to electrical
interference. In Discrimination
Mode, electrical interference may cause the F75 to chatter or beep
spontaneously. Indoor use, or use in proximity to buried or overhead power
lines, will result in chatter at high sensitivity settings.

To overcome chatter, which is usually due to electrical interference,
you can:

1. Try sweeping it over the ground.
If the F75 chatters while held still, or held up in the air, it
may be much quieter
when sweeping over the ground.

or 2. REDUCE the SENSITIVITY.
At a reduced sensitivity level, the F75 will still give good
detection depth.
Reduce sensitivity until the chatter stops. This may be a very low
setting.

or 3. Search in an All-Metal Mode.
Interference is much more tolerable in these modes, even at high
sensitivity.


SENSITIVITY FEATURES
Sensitivity settings from 1 to 29 have the following characteristics:
¡ü In an All-Metal Mode, you may notice more background noise than
at higher (30-99) settings.
¡ü The F75 will be more resistant to overloading on large targets
or salt water at settings of 1-29.

You may find that sensitivity increases as you increase the
discrimination level.
This behavior is normal for the F75. If increased discrimination
results in chatter,
then reduce the Sensitivity Setting.


BATTERIES
You may experience ¡Èchatter¡É or erratic behavior if using
inferior batteries, or discharged batteries.
If the lowest battery bar flashes, replace the batteries.
If all battery bars disappear, replace the batteries.
Use only battery types as recommended on page 6 of the manual.
Do not use ordinary zinc-carbon batteries.

-----Original Message-----
From: Fisher Research Customer Service
Sent: Tuesday, May 29, 2007 8:59 AM
To: John Griffin
Subject: FW: Industrial Section Feedback from charles graves






Message/Comments
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

hello, i am ready to buy my next detector(f-75)but i am hearing/reading
about electrical interference problems that have not been resolved.
have you diagnosed the problem yet?



Edited 1 time(s). Last edit at 05/30/2007 03:06AM by seeker41.

Hmmmmmm....... Let me cut-n-paste something directly from the e-letter;

"There are no electrical interference problems with the detector."

"Such high sensitivity makes the F75 susceptible to electrical
interference."

"In Discrimination
Mode, electrical interference may cause the F75 to chatter or beep
spontaneously."

Hmmmmmm........


And I run my batteries in the F-75 until they are so low..... that the unit will auto-shut-off. I have NEVER experienced interference due to low batteries. That's why "voltage regulators" were invented/utilized.

I have had interference issues that were so bad with the F-75..... that I had to leave the area..... regardless of where Sens & Discrim were set. ((( CZ had no interference issues at same site))). Yet..... on the other hand...... I will NEVER be without an F-75 do to it's superior attributes over all other detectors ..... in other environments.

Tom