Emi At Its Worst

[Mark Gillespie]

Spent well over an hour yesterday evening trying to quieten down the machine with absolutely no success.
Went through each frequency, sensitivity 5, GB.
Adjusted threshold and nothing helped.
SB through the entire range of options, could never get a quiet setting, nothing helped.
Turned on Black sand, no help there.
Screen displayed random numbers, EMI at the worse of any machine I've ever had.
Adjusted the GB up and down, no good.
Now I could reduce the sensitivity to 2 and this helped but the machine couldn't not detect a 4" dime in the ground. No joys here.
Increased the sens back to 5 and could only randomly get an audio on the 4" dime.
This is my 3rd trip to this site in and attempt to hunt. Most successful was the TDI SL with the 7 1/2" coil and to think I had contemplated selling the TDI to get a Tarsacci. Man, glad that didn't happen.
This is the area I've always talked about, being the bad, coke waste school.
Big difference between silent and auditable EMI. EMI completely shuts down this machine.


Only remedy was to move 50 yards away. Leaves a lot of questions.

[JCR]

Any idea of the source of the EMI?

[F350Platinum]

Seems like underground power to me. 🤔

[Mark Gillespie]

Three horizontal power lines on T poles about 20' from the school property. 

[JCR]

That is aggravating. Maybe there is less interference in the evenings or early on a weekend morning.

[Mark Gillespie]

Revisited the site this afternoon. Took the Tarsacci with both coils. The 12" coil is much worse, had both types of EMI. With the stock coil I had silent, random ID numbers flashing continually. With the 12" coil I had both random ID numbers and audio tones. Experimented again but this time I combined more than one settings. Finally settled down enough to actually detect the 4" dime. Threshold -4, sensitivity 5.
Also took the Equinox 800, as a second test. Awful interference.
Went through all the programs and did a noise cancel. No joy.
Went through each frequency and noise cancel. No joy.
Went back to Beach 2 program because it is suppose to be reduced transmit power for salt water hunting. No joy.
Switched back to the best program I could find and reduced the sensitivity to 15, a lot quieter but could only get an iron audio on the 4" dime.
PP on the Equinox could find the dime no problem.
Never actually tried the prospecting mode, just to much added noise.
Well anyway, I gained back some of the painful confidence I had in the Tarsacci.
Wondering if there was a leaking transformer on one of the power poles. Just thinking.

[Digalicious]

That's some serious emi.

My worst emi site is near giant power towers, in which any SMF mode is out of the question. Emi is so bad there, that even 5, 10, and 15 khz are noisy. Noise really starts to get reduced with 20 khz, and is gone completely at 40 khz.

Also, you may already know this, but the larger coils are brutal in emi. In that scenario, I typically use an elliptical of around 10x5 or a 6" round. Both of those coils are significantly better in emi than the typical 11" round stock coils.

[Mark Gillespie]

I have the Coiltek 10x5 Nox coil for my Equinox.  Might try it next time.  Love this little coil, almost as deep as the stock coil.