Digger 45 said:
Took the f5 to a park that i go to today and it ran about normal, looks like EMI. I was able to run Gain at 70 and threshold at 0 a couple of times i had to go -1 on the threshold but could not run ++9 at all way too hot for that park.
So it looks like another EMI problem that has to be adjusted out.
Well, it sounds like today you were able to adjust it to a level of operational anyway and that's good.
Lets see if we can clear the air a bit about the "Threshold" and the plus and minus of it and I expect Mike to chime in on this as well.
I've not owned an F5, I did own an Omega which is a little bit more of an automated F5 but the two are build offs of the same platform. Both my brothers have owned or still owns an F5, I've owned a few others detectors that have had an adjustable threshold (modern description of threshold anyway)
I have a downloaded version of the F5 manual in my computer that I fall back on whenever I'm trying to help others.
Lets go with modern terms of the threshold in use with detectors that are classed "Silent Search" models or types, like the F5, Omega, F70, Coinstrike, and so on. To use them in the silent search operation is to have the threshold set @ (0) or any minus number below that, this keeps out the "hum or electronic noise of the detector itself (old units actually produced an "audible tone" that was adjustable) running the threshold into the plus number range in some manuals is termed "Operating In The Noise" some manuals state that doing this isn't recommended except for the most seasoned treasure hunters. Running in the noise which for me sounds like static or mild EMI tends to add to the confusion of the detector noise, ground noise, EMI, and weak or faint target responses, this is why running in the noise is best suited for the 'Elite' most experienced hunters and with a lot of time spent running that model of detector. I don't see anything in the F5 manual that states that at some point in the positive threshold number range that it reverts back to SILENT SEARCH, so @ a positive 9 (+9) your more into the noise than @ +3 or +4
Running these units into the noise also makes the audio amp VERY JUMPY with almost anything because the audio circuit is already triggered (producing audio to the operator) so anything and everything going on in the circuits changes this produced noise, up and down. So, if electrical interference (EMI) is present your going to be hearing it in the mix as well.
If the EMI is strong enough it can bleed over a VERY wide frequency range, or if its weak but close to the operating frequency of the detector it can make detecting near impossible no matter what you do, but if its mild EMI adjusting the threshold back out of the noise can help to sort out what's EMI with the detector noise eliminated and the audio amp less jumpy you can often times adjust out enough of the EMI effects to continue to hunt.
I believe that your F5 with the Gain @ 70 and the threshold @ -2 or -3 is still running pretty hot for MOST coin hunting in places where the area hasn't been back filled anyway.
For shallow clad hunting I'm certain that moderate settings like Gain @ 40 and the threshold @ -5 will get you good depth on coins. They are some people that no matter what they are hunting they think they have to RUN MAXED out and in many cases that's just not true. Also, I've found that it the dog days of summer when its really hot and dry that my detector depth falls off a lot. When this happens those prime old coin area its best to hunt in the very early morning or a day or so after a good rain, you'll have less solar interference, you'll have less WIFI interference, the detector will be more stable and you'll get the most depth possible. Early spring and or late fall are GREAT times as well. Full sun, 90 plus degree heat and ALL my detectors are blown away with interference, I've started in the morning hunting an area, hunting DEEP with hot settings and by noon I had my setting so backed off trying control false signals and interference I just had to give up and call it a day. The only thing that had really changed about the area was HEAT, and full SUN! I've had this happen on many occasions!
Good Luck