In-line-filter for EMI RFI interference

[Shooter1]

Has anyone tried an in-line filter on their Tek's. Theyr'e suppose to clip on the cable just before the control box and reduce interference so you can run the detector with more sensitivity and gain. Thanks

 

[colt]

There are some places I can't hunt with a T2 due to EMI.

 

[Mega]

A total waste of time,in theory they are supposed to work but in practice they dont do anything.

 

[MarkCZ]

Well, they do what they do!
Its just that in most cases for a metal detector its not enough help to notice!
There has been a couple people that have stated the filters helped them, but I've bought them for ALL my detectors and ALL my extra coils and so far I can't tell a difference in any of them!
Now, with a different type of cable,
A different type of interference,
and a different type of electronic devise then they would probably be of more use.

Also, if a metal detector manufacture that builds $1,000 PLUS detectors could make them run a LOT better by just adding a $.75 (cents) filter to the cable I would think they would do it? The companies could actually get them for less than $.25 a piece by buying them in HUGE lots.

I left them on my coils, I know they work (that is to say they do what they do) so maybe in the right place and the right interference they may help and I got them for well under a buck on flea-bay.

If you decide to buy them don't buy them under a metal detector accessories just figure out what millimeter you need (I think the newer cables is 7mm) then just do a search for "7mm clip on EMI filters" you will find the EXACT same thing for under a dollar! to narrow the search just add TDK to the search and you will even get the same brand and for less than a dollar shipped (if you buy like 5 or more)

Mark

 

[Dave J.]

7 mm is the correct ID, although 6 mm may fit. Check Radio Shack and other electronics outfits.

In theory they can help in some circumstances. Among customers who have tried them, results have been decidely mixed. In any case they will help only with VHF-UHF interference and are of no use for things like powerline interference.

The theory that beeper manufacturers don't include them as standard equipment because they might cost a buck is erroneous. The things add weight and may increase connector problems which are among the most common problems in metal detectors to begin with anyhow. All complicated by the fact that for many customers there will be no benefit.

--Dave J.

 

[Justin E]

Dave J. did bring up an interesting point. If they were miracle cures for emi, wouldn't detector companies put them on straight from the factory? If it were me, I would wait and see FT's answer to the problem. I say they've been working on a fix on the emi problems for a while, as have all detector companies.

 

[MarkCZ]

In theory they can help in some circumstances. Among customers who have tried them, results have been decidely mixed. In any case they will help only with VHF-UHF interference and are of no use for things like powerline interference.

Lets see if I have this correct?
In the above mentioning of presents of "Power Lines" your are talking about being near enough to them to be in somewhat the field of inductance that surrounds the power lines as the AC voltage passes through the wire, or to say in the cloud of energy around the power lines. (radiated energy)

But the EMI filters would have a greater benefit with "Transmitted RF Type Signals" like Television and or radio broadcast, because the filters help to cancel out the cables "Antenna Like Effect".

So, in the case of power line inductance all the electronics of the detector would be in the field of AC energy and so the Clip-On cable filters wouldn't be of much use?

The theory that beeper manufacturers don't include them as standard equipment because they might cost a buck is erroneous.
--Dave J.

If you were referring to my comment about the cost of the filters being less than a buck, I was saying that if for a few cents the filters really had a positive effect on smoothing out the operation of their detectors that the companies would have already incorporated them into the coil cables.

I Was in NO Way saying that the manufactures don't because its a way to save a dollar, but that they don't because in Most All cases they just don't help.

Thanks again Dave for your valued input here on the forum!

Mark

 

[Darkflamedesign]

They have helped some ... I was able to reduce " cycling " in audio . You must clip at the end prior to control box . They are inexpensive and are available just about everywhere .
All of my coil setups have them ... The problem with the omega EMI is simple ..... It is the coil cable being " under" shielded . I have had better response with a RF shield sleeve that i wrap around coil cable .

 

[elki1052]

Okay here is what I know about those filters;
I work on Electronics and the machines that I work on use them for filtering noise created by the machine electronics itself not for external interference of other divices.
there are digital devices that produce a noise on its electronics and that noise creates problems on the process of the data or input/output, for that reason the filters are install.
it is like day or night difference with or with out on them but in order to work correctly the filters have to be install on the right orientation + positive or - negative direction and the wire (cable) or in this case harness ( which some times is made of many single cables) it has to make a loop on and into the filter at lease one time, this means that the end of the cable has to go inside the filter opening at lease 2 times.
A good example is on the fax machines, the phone cord needs to have a filter and the cord goes into the filter at lease 2 times, that is because the noise will produce a dirty copy (fax) on the receiving end, if the fax machine produces a bad copy then you add one more loop to the filter and just like by miracle the fax (copy) comes clean.
So if I'm correct on this the filter should able to allow the cable to go into at lease 2 times to create one loop around the filter.
One of the reasons that the detectors manufactures said that you should loop around the cable tight on the shaft is to allow the extra noise generated by the resonance of the coil to filter out on the cable it self wile been on contact with the shaft. it's like creating a protective shield to the signal from and to the detector.

I don't know if will work for external noise coming from power lines or large electrical motor because I thing that type of noise is been absorbed by the coil and through the cable of the coil.
but for sure should help with the noise generated by the electronics of the detector preventing the resonance of them up and down through the coil.

HH.

 

[MarkCZ]

They have helped some ... I was able to reduce " cycling " in audio . You must clip at the end prior to control box . They are inexpensive and are available just about everywhere .
All of my coil setups have them ... The problem with the omega EMI is simple ..... It is the coil cable being " under" shielded . I have had better response with a RF shield sleeve that i wrap around coil cable .

Then that problem should be in the Alfa, the Omega, Delta, F5 ect, they all use the same coils.
I don't have any more trouble with EMI with the Omega than I do with any other detector, I think some people that are having trouble with the Omega are trying to run it to hot. The manual states that a sensitivity setting above 70 (I believe its 70) shifts the detector into another gear (two stage sensitivity) but it puts the detector into a noise range of the electronics, which takes a lot more skill to operate that way.
I usually run mine @ 65 to 68 which gets me down to around the 8" running depth in WV soil.

Mark

 

[MarkCZ]

Okay here is what I know about those filters;
I work on Electronics and the machines that I work on use them for filtering noise created by the machine electronics itself not for external interference of other divices.
there are digital devices that produce a noise on its electronics and that noise creates problems on the process of the data or input/output, for that reason the filters are install.
it is like day or night difference with or with out on them but in order to work correctly the filters have to be install on the right orientation + positive or - negative direction and the wire (cable) or in this case harness ( which some times is made of many single cables) it has to make a loop on and into the filter at lease one time, this means that the end of the cable has to go inside the filter opening at lease 2 times.
A good example is on the fax machines, the phone cord needs to have a filter and the cord goes into the filter at lease 2 times, that is because the noise will produce a dirty copy (fax) on the receiving end, if the fax machine produces a bad copy then you add one more loop to the filter and just like by miracle the fax (copy) comes clean.
So if I'm correct on this the filter should able to allow the cable to go into at lease 2 times to create one loop around the filter.
One of the reasons that the detectors manufactures said that you should loop around the cable tight on the shaft is to allow the extra noise generated by the resonance of the coil to filter out on the cable it self wile been on contact with the shaft. it's like creating a protective shield to the signal from and to the detector.

I don't know if will work for external noise coming from power lines or large electrical motor because I thing that type of noise is been absorbed by the coil and through the cable of the coil.
but for sure should help with the noise generated by the electronics of the detector preventing the resonance of them up and down through the coil.
HH.

Actually tight rapping of the coil's cable up the staff is often disputed by these companies technicians, even though they keep putting that information in the manuals "Wrap The Coil Cable Tightly Up The Staff" Its my understanding that what they are trying to do is to neatly and snugly wrap the cable so that it doesn't flop or wiggle. But tight wrapping stresses the cable a lot and if you change your coils often the tight wraps turns the cable into a coiled looking phone cord.
I never liked the tight wrapping so when Dave_J suggested using a "Hank Style Wrap" I was very quick to convert, retraining my Coin$trike cable was a little trouble.

Mark

 

[jabbo]

n/t

 

[MarkCZ]

Here our a couple of pictures of both a long cable "Hank" and a short cable "Hank"

Coming off the coil I make one small flex loop (starter loop) then Velcro it straight of the shaft.

Mark