Noise cancelling question.

[Mick in Dubbo]

I'm curious, How you know which is the best Chanel to select when you have to manually noise cancel? Although I have the 70 with it's auto mode, I was showing a newbie around a 305 the other day and apart from observing the effects of EMI after using it for a while. This doesn't necessarily give me the best Chanel (I assume). Hence, the question.
Thanks.
Mick Evans.

 

[Digger]

Mick, I'm not sure what you mean by "best". If by best you mean which channel is less receptive to the electrical interference, then without Auto NC, we have to depend on our ears. The harmonic frequencies of electrical interference will cause chatter, intermittent noise or falsing, even when you aren't moving the coil. If that occurs, we shift the operating frequency a bit by changing the NC channel. If you find yourself in a site where it seems impossible to find a quiet channel, changing to a different frequency of coil can sometimes eliminate the problem.
If you were asking which channel is "best" based on having several "quiet" channels, with best being the most sensitive or deepest seeking, I've not found any difference. When I was field testing the X-TERRA I always ran a NC prior to, and several times during, the tests. When I would hit a target, I'd switch channels prior to digging the target, to see if there was any difference in the depth of detection or separation. What I found is, if the channel is "noise free", it is no better or worse than any other "noise free" channel at that site, on any one target. I did find, however, that having a channel that was "noisy" did provide a broken audio response on some of the deeper targets. JMHO HH Randy

 

[Mick in Dubbo]

Thanks Randy.
I have found that interference on the X-Terra is mostly subtle. That is, it won't usually false and be noisy like most detectors behave but rather the TID would be a jumpy on good targets and not give an accurate reading. Also the other big give away is that the depth meter will max out on all targets. it only seems to happen with the medium frequency coil as the high frequency coils seem to be immune to the EMI. I've only recently bought the low frequency coil and can only assume that it won't have any issues that way. It's funny, because a number of other detectors that I've owned, operate on the same frequency as the X-Terra, but without the same issue. but both X-Terra's have suffered from it though.
I'm about to go for a hunt now. got a new spot and have an RDO, so it's time to have a bit of fun.
Mick Evans.

 

[hotrod53]

I also discovered last weekend that it is not just power lines and random EMI, but it makes it play nice with detectors around you. I found a quiet channel and a buddy walked up on me with another 705, his detector went nuts. He was no closer than 10 feet and it went wacko, tell me the field on these things isn't strong! He did a channel search and from then on we could hunt right next to each other.