GPX5000 – How to deal with EMI
What is EMI? It is short for Electromagnetic Interference. While a single frequency VLF is hardly affected by EMI if at all, a high powered Multi Period Pulse induction machine like a GPX series unit will suffer from EMI to various degrees depending on location, time of day, weather, and even the time of year. In general terms, a hot windy day in the middle of summer will usually have high levels of EMI causing a lot of “chatter” in your machine, whereas a nice cool still evening late in Autumn will have very low levels of EMI.
This EMI can be quite noticeable on both the GPX5000 & 4500, but what are the reasons?
1. The high sensitivity of Enhance, Fine-Gold and Sharp timings will pick up extremely small nuggets, but unfortunately are also more sensitive to EMI as well.
2. Because of the superior ground handling ability, the use of big Monoloop coils has become more common nowadays. A coils field punches just as high above the ground as it does into the ground, in simple terms you are using a bigger antenna, so you can see that a bigger deeper coil will be more likely to pick up on EMI.
3. The general smoothness of the detector means that any warbles or chatter due to EMI are a lot more obvious, and can be mistaken for a target signal.
So what can you do to keep detecting? Here are a few tips that can keep your threshold purring:
1. Use a DD coil, and/or keep the coil size to a minimum for the ground being worked. Remember, a smaller mono will always pick up less EMI than a larger mono.
2. Avoid using the Fine-Gold and Sharp Timings. Normal and Sensitive Extra will often provide a smoother threshold.
3. Use the Very Slow or Slow Motion Speed settings. Medium and Fast will pick up a lot more EMI.
4. Use the Quiet or Normal Audio Type
5. When performing an Auto Tune, to help the detector to accurately pick the quietest operating channel, select the Fast Motion speed, then do an Auto tune, and then go back to Very Slow Motion.
6. Set your Rx Gain first, and then use the Stabilizer to fine tune.
7. Whilst searching, you may find that the threshold starts to wobble. A quick tweak of the manual tune by a few numbers normally keeps it running nice and stable.
A combination of the above should make a big difference in the stability of the detector, and will allow you to continue to find gold in difficult conditions.