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Why is my F5 OUTPERFORMING my F70 :confused:

C

Cal_Cobra

Active member
I met up with another detectorists today at a park I'd been eying for a while and brought both my F5 and my F70. I brought the F5 to test how it did with the F4 DD coil. It actually did OK, except that the pinpoint was way off, so you could only pinpoint via the X pattern (the pinpoint function was way off, as the target would always be way outside the hole). Satisfied with my F5 DD coil test, I switched to my F70. It was a chatter box. I had it setup with sens anywhere between 30-65, and found that I could only run it around 30 for any kind of stability, threshold had to be kept in the negative, I had nothing notched, disc at 6, speed set to DE or SL didn't really matter, and 3H tones. Also tried switching the frequency to see if it was picking up EMI, no change. It was such a chatter box I decided to put the F5 stock coil back on the F5 and see how it did. Sure enough, I was able to crank the sens to 90, threshold to max, and it ran like a champ.

If the F5 can run maxed out, I'd expect I should be able to run the F70 at a higher sens setting then 30 (it was still chattery at 30). It would make sense if both machines were behaving in a similar manor, as it would seem to indicate erratic ground, EMI, or some commonality, but this isn't adding up.

Should I send my F70 in for a checkup?

HH,
Brian
 
Interference Factors:

The Source

1. Field Strength
2. Frequency
3. Bandwidth(Harmonics)
4. Polarization

The Detector

A. The Coil

1. Frequency of the coil.
2. Shielding of the coil.
3. Unintentional resonant circuit caused by coil components.

B. The Coil Cable

1. Shielding.
2. Cable length.
3. Balanced versus unbalanced configuration.

C. The Control Box

1. Shielding(The control panel is often overlooked as a portal).
2. Filtering.

D. Battery Box Cable

1. Having the coil cable stretched in one direction, and the battery cable in another with the control box in the middle, creates a very efficient antenna configuration known as a Dipole.

()-----------------[]-----------------{}
Coil............Control............Battery

The above is not exhaustive but does give some idea of how many variables come into play when you have an interference problem. Just because Detector A experiences interference doesn't mean Detector B will. I would take the F70 to several locations without any other detectors running within a 100ft before I decided if it was defective, or just the nature of the beast.

HH
BarnacleBill
 
Did you try rebooting it? I have never had a place I couldn't MD. When mine gets that way, Rebooting has always worked for me.
 
I would send the unit in to be checked out, something is not right with your F70. All these problems with chattering, is just not right. The F70 is a great unit, and I haven't had anyone that I sold them to complain about that.

Just guessing here, but it sounds like a flunky coil. Have you tried a different coil, one that was designed for a F70/F75 ?
 
It didn't seem like an EMI problem as much as it seemed to chatter on the ground like the ground was loaded with rusty iron, giving all kinds of non-repeatable signals. I've experienced EMI on other machines, so I understand it's behavior pretty well (my C$ is really prone to EMI).

John I'll try giving it a reboot first, that's a good idea.

Bill I have the small Fisher 6.5" F70/F75 coil, I'll try that today and see how it acts (Just to clarify, I wasn't using the F4 DD on the F70, only on the F5. The F70 had the stock F70 coil on). I bypassed the Sunray inline probe just to make sure that wasn't part of the equation, it didn't change anything.

Thanks everyone for the help.
Brian
 
Hey down here in sac!...My f70 gets a little chattery sometimes....let me know if the coil switch helps?....I have a f75 and f70...haven't even used the f75 yet?...too many detectors.?
 
First off, the F-4 DD isn't the proper coil for the F-5. The F-5 can use coils from the new Gamma and Omega. I haven't personally done this test (since you have my old F-4 :) ) but I would guess that since the F-4 coil on the F-5 works but at a significant loss of performance, running that combination might give the impression of better stability when it's really a product of lowered performance. Did you try running the stock coil on the F-5 during this test? Again, if I had to guess, the 70 may have a coil or some other problem but comparing it to the F-5 and an F-4 coil is flawed from the start. So tell me this Brian, would you still rather eat gun powder and skip a Girls Gone Wild video shoot than send a unit back to the factory for a checkup? :rofl: Just kiddin' Bud.
 
Late night, no coffee yet, and with those two factors in place, my read to comprehend skills are about like running an F-4 coil on an F-5...... just not up to snuff. :rofl: Sorry about that. :wacko:
 
Hi mascard1.

Being a little chattery doesn't suggest a bad coil. Generally it would suggest the adjustments are out for the ground your hunting. I do believe that Cal has mentioned for some time that he is having a lot of un-stableness with his F70. That's why I suggested that perhaps there's something wrong such as his coil. :)

If your hunting in the "SL" mode, the instructions states that the detector is likely to operate more noisy than in the "DE" mode. Overall, I have had good luck with the F70. It certainly is a deep hunter.

Brrr, snowing again. Too cold to go detecting. :cry:
 
I have problems with my F75 after a big rain or if the ground is wet or the grass is wet. It may be how you fast grab the trick is to do a pinpoint and find clean ground and then fast grab also you have to have top of the line AA on my F75 and sometimes I have to reset it. Also sometimes I have to go with the small coil. The F75/70 is a hot machine it is not always perfect and can be really tough every once in awhile. Just the beauty of the beast and most of us have a backup just for what is happening..Did you turn off your phone were you close to a police station or fire deparment.
 
Did you try a small coil on F70..Did it ground balance properly ? What was the FEo reading ??
The F70 is much more powerful than the F5..................??????????????????

Have you considered your coil may be bad on the F70 ??
Did you check the connection point of coil ? Is it loose ??? on the F70


Is that the proper coil on the F5 ???????
 
BuckeyeBrad said:
First off, the F-4 DD isn't the proper coil for the F-5. The F-5 can use coils from the new Gamma and Omega. I haven't personally done this test (since you have my old F-4 :) ) but I would guess that since the F-4 coil on the F-5 works but at a significant loss of performance, running that combination might give the impression of better stability when it's really a product of lowered performance. Did you try running the stock coil on the F-5 during this test? Again, if I had to guess, the 70 may have a coil or some other problem but comparing it to the F-5 and an F-4 coil is flawed from the start. So tell me this Brian, would you still rather eat gun powder and skip a Girls Gone Wild video shoot than send a unit back to the factory for a checkup? :rofl: Just kiddin' Bud.
Click to expand...

I believe Brads post is tongue-in-cheek in it's entirety :poke:...but just so everyone is clear, the F5 only had the F4 DD coil on for like 10 minutes to see how the F4 DD coil worked on it (really didn't have diminished performance, aside from the pinpointing snafu). After the test I switched back to the stock F5 coil that came with the F5 ( I should have put that in a separate post, as the F4 coil has nothing to do with the F70 trouble). Then I switched to the F70 with the stock F70 coil to hunt the park, but due to it's erratic chatterbox behavior, I grabbed to F5 with the stock F5 coil to hunt and it performed like a champ.
 
Bill is right, it's been chattery since I first got it. I almost exclusively run it in DE mode, I've tried SL mode, and don't see a lot of difference aside from extra noise, but not the extra depth it's advertised to gain in SL mode. I have to hunt with really low sensitivity settings (in the 30's) which does OK for targets 6" or less, but any modern machine will find targets 6" or less IMHO.

It's definitely properly ground balanced (very easy to do, just like the F5 phase button or the C$), the FEo reading is only one bar, if that, depending upon where I'm hunting, so it doesn't appear to be highly mineralized where I've been hunting, I leave my cell phone in my car when I'm hunting, and it's been the same behavior in all hunting sites unless I run the sens around 30. I've checked the coil connection and even removed the Sunray inline probe from the equation to eliminate it as a source of failure, but it still behaves the same. It's pouring rain today, if the weather breaks I'll test it outside with the small coil and see if the stock coil is the culprit. Another thing I've noticed is that I don't get any of these crazy 11" on a dime or 12" on a quarter air tests like a lot of folks post, my air tests seem to be stuck around 6"-7".

The F70 is touted as a deep seeker like it's F75 brother, which is the reason I went for it. Hopefully there's something Fisher can tweak or replace on this machine to get it on par with what it's capable of doing.

Thanks for all the ideas and suggestions,
Brian
 
Try and get it fixed before the 14th of March.

LowBoy
 
I got an RMA opened with Fisher to have the F70 checked out. I spoke with Felix, and as long as they receive it by this Thursday, he said he'll get it back to me by early next week (can't beat that!).

I'm hoping they find the issue and it doesn't come back as NTF.

HH,
Brian
 
LowBoy said:
Did you turn off your phone were you close to a police station or fire deparment.
Click to expand...

or DOT, or cell tower, or DTV antennae, or NAVAID, or airport, or car radio, or electrical wire, OR was there high sunspot activity on that day? :laugh: Couldn't resist.... at a public park (or any other place where coins might be) you either have to let it sound like a Geiger counter on 'roids or reduce the sens so low you end up with same performance as an f4. :cry:
 
Shambler said:
LowBoy said:
Did you turn off your phone were you close to a police station or fire deparment.
Click to expand...

or DOT, or cell tower, or DTV antennae, or NAVAID, or airport, or car radio, or electrical wire, OR was there high sunspot activity on that day? :laugh: Couldn't resist.... at a public park (or any other place where coins might be) you either have to let it sound like a Geiger counter on 'roids or reduce the sens so low you end up with same performance as an f4. :cry:
Click to expand...

It's definitely NOT an EMI issue. I'm pretty familiar with EMI (I'm an engineer at Cisco, although not specifically an RF engineer, I know what it is). My Coinstrike was fairly prone to EMI at times, the F70 issue was nothing like that and seems to happen everywhere. Also my buddy I was hunting with had the Whites MXT which operates around 14kHz, and his machine ran great (and we were hundreds of feet apart most of the time, so it wasn't machine crosstalk).

Hope Fisher figures this out, as much as I love the F5, it doesn't have the punch that the F70 is reported to have, and I need that, there's too darn many Explorers out here :starwars:
 
My F70 was just great in farmfields but once I took it to my forrested park, the unit became useless. Even with the lowest sensitivity settings, it kept on chattering. Not useable if not a nightmare. I could not understand it as I tried everything. I had to take out my old whites classic II and hunted with sens MAX and had a great day with it. On other locations it was performing well.

At time the F70 reminded me of taking a 1266 to an iron infested spot.

Eric.
 
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