I have posted my impressions of the 12x15 before, basically it boils down to the thing being crazy sensitive to EMI. But if you take it out into a field or big park you can run it hot enough to go deep. Well, today I went to a school and forgot my backup coil. Try as i might I couldn't calm the 12x15 SEF down, ran the rx down to 3 and the sens to 60 and it would still false like crazy.
I cycled through the frequencies one at a time, and on each offset trying to find the quietest setting. Then when I found the best combination (7.5khz +3 offset; still falsing pretty bad) I decided to change the filter as well. As soon as I changed from 5 high to 5 band, the thing went silent. I was able to crank it to 12 70 92 and it stayed completely quiet.
At this setting I was hitting coins 7-10 inches for the next 4 hours. I air tested the first dime I found (a silver Rosie) and could easily detect it from a foot in the air.
While I prefer to run all three frequencies (helps with those pesky bottle caps), I was pretty amazed at the performance of the coil once I found the combination to knock the EMI out. Not sure why the filter change did the trick, but i'm not complaining.
I cycled through the frequencies one at a time, and on each offset trying to find the quietest setting. Then when I found the best combination (7.5khz +3 offset; still falsing pretty bad) I decided to change the filter as well. As soon as I changed from 5 high to 5 band, the thing went silent. I was able to crank it to 12 70 92 and it stayed completely quiet.
At this setting I was hitting coins 7-10 inches for the next 4 hours. I air tested the first dime I found (a silver Rosie) and could easily detect it from a foot in the air.
While I prefer to run all three frequencies (helps with those pesky bottle caps), I was pretty amazed at the performance of the coil once I found the combination to knock the EMI out. Not sure why the filter change did the trick, but i'm not complaining.