SURF PI INTERFERENCE PROBLEM

[daverave]

My surf pi is very stable on most beaches but when im on my local beach where there are amusement arcades nearby...my detector becomes very chattery....what can i do to get rid of this problem ???? would screening the pcb stop this ?????

[SVEN1]

EMI.
Smaller coil will help.
I find putting the PCB into a metal enclosure also helps.
I have a frequency control on my PI, not a Surfmaster, which helps tune it out.

[sinclairuser]

one of those clip on chokes, added to the coil wire about 2" from the enclosure can make a big difference, they are cheap so worth a try.

[SVEN1]

I never found those clip on chokers to work on any of the VLF or PI machines I have ever had.
There are so many different chokes to cover so many frequencies, you might as well bead your coil cable up with them in hopes one will work.
And EMI from different sources can come and go, manmade or naturally occuring.
PI's are naturally bothered by EMI top some extent, the larger the coil the worse it can get. Especailly if the coil has no shielding. You coax is shielded to begin with.

Try a simple fix first put your PCB in a metal box.

[daverave]

my surf pi is housed in a plastic box so i may have to use aluminium foil around the pcb....i have tried chokes but never had much success with them but i will have to experiment again....on the main beach where i live lots of arcades running along main road and the detector is so chattery....ive started using my pi on dry sand instead of my tesoro detector and i find the surf pi works well so i can search both dry and wet sand with the one machine.

[SVEN1]

I had a similar issue at a beach where i used to hunt. The closer I got to the marina side of the beach, the EMI came and when. It was annoying to hunt that section.
Mind you it was the same area that effected my VLF machine.
Originally both my land and water PI units were housed in plastic boxes, no shielding.
Then decided to try something different after seeing an Eric Foster water machine. Inside the plastic box was a metal box that enclosed the PCB.
Gave me and idea to line my box with copper foil tape with conductive adhesive, the two coats of epoxy, solder a wire to the lid and inner box and ground the wires to the PCB.
It definitly has helped.

My latest build I built an internal copper box, using copper clad PCB boards.

[daverave]

i will try and use aluminium foil and hopefully this will reduce the chatter....do you think having a frequency offset control helps ???? i very much like your yellow box !!!! ive never seen these boxes in the uk....im thinking of using metal box in my next project...its only a certain part of the beach that i have this problem which is close to amusement arcades....other parts of the beach very stable threshold.

[SVEN1]

My land units all have a metal box.