Ground balance of the F-75 question ...

[Willee - Texas]

This evening I visited a Middle school just a few blocks from my house.
The F-75 SE would not ground grab ... As I pumped the coil the number just stayed on whatever it was on.
I tried several areas with the same result.

When I got home I tried ground grab in my back yard and it ground balanced at 41.
Switching to all metal mode the detector sounded off as the coil approached the ground.
I switched to manual Ground Balance and was able to balance it out at 30.

Does this sound normal?

Willee

 

[gmanlight]

Willee the F75 will not GG below 40
If soil is below forty , mostly found at a beach , switch to AM and
GB manually then switch back to Disc mode.
I believe , someone jump in if I'm wrong.

Page 15 of manual

 

[WV62]

Willee the F75 will not GG below 40
If soil is below forty , mostly found at a beach , switch to AM and
GB manually then switch back to Disc mode.
I believe , someone jump in if I'm wrong.

Page 15 of manual

Right on,

Ron in WV

 

[Monte]

This evening I visited a Middle school just a few blocks from my house.

My question is where and what conditions? You didn't mention where (location) your house is ,or the middle School, which might suggest a ground type. If you are in or near Corpus Christi, then I might guess you have rather mellow ground. I haven't hunted in Texas since '90 but was thrilled to work that gentle soil.

The F-75 SE would not ground grab ... As I pumped the coil the number just stayed on whatever it was on.
I tried several areas with the same result.

When I got home I tried ground grab in my back yard and it ground balanced at 41.
Switching to all metal mode the detector sounded off as the coil approached the ground.
I switched to manual Ground Balance and was able to balance it out at 30.

Your question: Does this sound normal?

My answer is Yes, it does sound normal, as others have mentioned below. If you select the All Metal mode, or the pinpoint function, with the coil several inches off the ground, then lower it toward the ground and the audio increases from the Threshold setting, then (if you're not over a metal target) it suggests the GB is a bit too positive.

If the GB phase is set at '41', as you mentioned, and and the audio increased when you lowered it, then the GB was too positive which is just what you discovered with a manual GB that balanced at '30.' So, yes, what you did was what I would call 'normal,' especially in good (very mellow) ground.

Monte

 

[Willee - Texas]

Thanks for the reply Monte ...
The ground here is a dark grey clay and sand type of soil.

I was puzzled the F-75 would not Ground Grab at the school yard just a few blocks from my house.
Perhaps I will do a video about that to show it better than I can explain it.

Willee

 

[Dave J.]

No need for a video, Willee. The F75 won't GB to 40 or below other than manually. This limitation is an intentional feature, to prevent ground balancing over metal.

Fisher Research Lab is among other things a soils research lab. I have a dollar that says you live within 300 miles of the Garrett factory. If I'm wrong, PM me and a dollar bill out of my own pocket (autographed in ink as a souvenir) will be in the mail to you shortly.

Heck, it's only a buck, and for fun at that. Just PM me and tell me where you live and even if it's within 300 miles of the Garrett factory the buck is yours, you'll have provided one more piece of data for the Fisher Research Lab dirt archives. Useful information for only a buck, not many research bargains that good left in the world.


--Dave J.