Sunray S1giving different reading than Sov coil?

[CLOAR]

While there's no arguing the S1 is a great pin pointer, I keep reading posts that imply the S1 can be used in conjunction with a 180 meter. While it works... my S1 has always delivered a reading consistently 4 digits lower than the Sov.

I now have a new Sov GT with the Tornado 1000 coil and a new Digisearch 180 meter. My S1 probe is about 2 years old. (Moved over from my Sov XS)

I can calibrate the meter (via the coil) to 180 using a new dime and the GT will lock dead-on at 180 every time... "BUT... if I switch over to the S1 probe, the meter will read 176! If I calibrate the S1 probe to 180, the S1 will lock dead-on at 180 every time... "BUT... when I switch over to coil, the meter will read 184.:veryangry:

I'm assuming it has something to do with the difference in inductance of the coil windings, resistance, voltages drops etc., between the GT coil and those of the S1 probe. I've always had this 4-digit difference between the S1 and the GT regardless of which one I use to calibrate the meter. The same situation occurred when I used it with my XS and an older rescaled 180 meter

I eventually got use to the 4-digit variance but I can't shake the feeling other SOV users with S1 probes get the same reading. In another post I read you could "internally" calibrate the meter to compensate for coil variance but I don't see how any meter calibration would compensate for the electrical differences between the S1 probe and the GT coil since the meter only has one input shared between the two.

NET: Can anyone suggest a modification I could make "inside" the S1 probe control box? Since the S1 control box allows access to both coil and probe circuits leading to the meter I was thinking I could add in an inductor or variable resister... to the coil or probe circuit that would allow me to change the electrical value of a circuit so the two would "match". Whatever component I add I want to make sure it won't impact the sensitivity.

Hmmm... maybe a good suggestion for Sunray and their next generation of probes. An access hole in the control box that would allow for adjustment of the probes electrical traits so the user could calibrate the probe regardless of what coil you are using.

Any electrical engineers out there with any suggestions? I was also thinking I could shorten the coil wire... but how much? I'd hate to cut it shorter only to have the situation reverse and have the coil read higher than the probe.

Thanks

 

[Art (NWOH)]

I would say that what you have is fairly normal.

Your probe is just a small coil, and different coils tend to need a little adjustment on the meter when switching from to another.

Getting a dead on reading with the probe is not as important as it's ability to discriminate by way of the Sov.

Most of the time you would just want to know where the coin is in the hole or the dirt pile without chasing nails around. It works good for that. You can tell by the audio.

As far as I can tell, your best choice is to leave it as is, and not worry about the difference in reading.

Most who have shortened cables have not had any significant problems. There is always the possibility that you could make your small problem worse.

HH

 

[Art (NWOH)]

I missed answering part of your question.

The internal adjustment on the meter can be used if for some reason that you can't adjust far enough with the external control. It will not adjust out the differences between different coils.

As far as modification so that the probe will be calibrated all the time, I cant think of a way to do it in the S-1 switch box.

However it could probably be done inside the meter if you have room. Would amount to adding in trim pot for probe adjustment and a small toggle switch for switching between the main calibration pot and the trim pot for the probe.
You would have to flip the switch to run off the right pot depending if you are using the probe or the main coil. Would be a lot of trouble to be fooling with.
HH

 

[Rick(ND)]

They use the S1 probe to find the target once they know it is one they want to dig. The only time you will want to use the S1 for iding is when you use it as a coil to get into tight places, then you can calibrate the meter to use to ID using the probe. I have never used the probe as a stand alone coil yet as i use my coil to ID so I know it is a target I want to dig, then switch to the S1 to find it.
Now on the iffy ones that are deeper than the meter can ID(you will know those with experience) where I will dig a plug and go into the hole with the S1 in all metal and get a decent signal, then switch to the disc mode to see if it is good or not, if it nulls it is trash, but if it is good the tone alone will let me know it is a good one.
I seen a few post like this over the years and if you really want to ID with your S1 probe just remember it is 3 or 4 number lower than when using the coil.To add anything into the meter or the probe control box to make both the probe and and coil read the same on the meter may make it take longer to use as you will have to have 2 differnt calibration controls and recalibrate both everytime you use it or change coils and even when the temp changes as it will drift numbers.
As you see it is a lot easier to just ID with you coil and use the S1 for locating the target, or remember there is a 3 or 4 number difference between the coil and probe and if you change to a bigger coil there will be a bigger difference.
I dont feel changing the lenght of the cable will make much difference in the meter reading as the winding in the coil is where I feel the difference is.

What do you think of the GT over the XS you were using??

Rick