I??ve used a GA-52 Schonstedt.?ÿ
I??ve used a GA-72 Schonstedt.
I??ve used a GA-92 Schonstedt. Pistol
The pistol has been in for repair 2x. The ribbon that connects the sliding extension seems to be the weak part.?ÿ
The GA 52 is my favorite. I??ve got a malfunctioning one now.?ÿ
The GA 72 works, but is not as versatile, because it uses clicks, for preset sensitivity positions.?ÿ
I also have the Javad. It??s not very versatile. It has to be used through the LS. This ties up the LS, and I don??t like that.?ÿ
Dunham and Morrow (supposedly leftovers employees of schonstedt) make one that is lighter than a schonstedt.?ÿ
of course there are several other brands. CST
and such.?ÿ
anyway, what have you used, and what is your favorite?
I'm probably just going to get my old 52, and 92 fixed. But, I??d like to see what options others are using. Metal detectors are critical, useful, and essentially indispensable to an honest surveyor. I also wish they could do more than ferrous metal. Aluminum and brass are also common monument material.
Thank you,
Nate?ÿ
I think all of those you mentioned are MAGNETIC locators, so won't find aluminum and brass caps. They respond to either changes in the earth's field induced by long iron objects, or to permanently magnetized objects.
For non-magnetic metals you need a conductivity detector, commonly known as a treasure hunter, which usually has a search coil several inches in diameter.
A rule of thumb for those is that they respond according to the product of the metal's electrical conductivity and the surface area presented to the coil, reduced by distance as compared to the diameter of the coil. Vertical extent of the object has very little effect on detection.There are some processing tricks that can often distinguish different metals, but I've not found mine to give reliable discrimination.
Aluminum has very good conductivity (after gold, silver, and copper in the commonly used metals). Bronze and brass are good. iron is somewhat less but not bad. But the top of a rebar, the most common monument, has small surface area, so gives a treasure hunter a lot less response than a big bronze cap. That's why surveyors carry magnetic locators as their main search machine.
As a bench mark hunter, I carry both kinds of detector, and use the treasure hunter much more of the time, because iron rods are not commonly used for NGS BMs. Bronze caps and stainless steel rods do not register on a magnetic locator. I've found many of the 1960's-70's USGS marks in this area used iron rods.
GA-52
In British Columbia, for about 2 years in the mid 1960's, aluminum bars were used as property corner monuments.
I can attest to the fact that aluminum is invisible to the common type of pin finder.
I used nothing but Schonstedt for 30+ years. I tried out a Magna-Trak 202 for a couple of days. I ended up buying it. I??m not saying it??s better. But it works just as well for me, it feels good in my hand, and it only cost me $450 used. 6-months and no issues.?ÿ
I liked the Subsurface ML1-M. Far easier to handle than the GA52, and in my opinion equally effective
I have a GA-52 I use on my County job.
I personally own and use a GA-32... yes, very old (I think I bought it around 1976) and needs headphones but I find that its so much more accurate in pinpointing a spot than the 52.?ÿ And with the 32 I can wave it over 2 or more feet of snow and it will 'respond' to an iron much better than the 52.?ÿ ?ÿSeems like the 52 needs to be held pretty much vertical to get any results... the 32 can be held almost horizontal and it will still work good.?ÿ Granted, the 52 is an older version (circa 1994)... maybe the new ones are better..don't know.?ÿ ?ÿ ?ÿ ?ÿ I do have a like new 32 as a backup.?ÿ
For locating objects that have no magnetic field I have an original Fisher Gold Bug.?ÿ Finding an old GLO concrete monument with brass cap (no embedded iron) is like finding gold!?ÿ The Gold Bug has come through several times looking for those!?ÿ ?ÿ It picks up on the brass - I 'tune' it buy throwing an unused brass cap on the ground and adjusting the settings on the Gold Bug to react to it.?ÿ?ÿ
The 32 is my favorite for sure.?ÿ?ÿ
?ÿ
Brass caps around here have a 24" iron pipe attached to them. They almost knock my Schonstedt 92 out of my hand.
When I'm randomly searching I turn up the sensitivity till it's almost beeping continuously. I find nails 1 foot away. Brass caps with iron pipe will beep almost 6 feet away. I've had it since 2004. I sent it in to Schonstedt once. They sent it back in a brand new case and fabric holster. Must have been that ribbon connector that went bad.
Using the meter I've located monuments so accurately the hole hardly has to be wide enough for the digging bar to hit the iron. Most Surveyors around here mount their aluminum cap on steel rebar so I've never had any problem finding them either.
I've had several client's try to find monuments with their treasure finders with no luck. They think I'm a magician when I tell them "Dig here" clink a steel pin.
I'm a total Schonstedt fan!
I love my GA-72. The meter and sensitivity setting sure helps with pinpointing location and determining depth of object.
I like a locator that easily indicates polarity and works along a chain link fence. A few models from a few brands can do this. I think it is a worthwhile feature.
@dmyhill I think this got talked about somewhere on here before.?ÿ Which brand do you use??ÿ And does it work like they claim??ÿ When I googled the feature this is what popped up for me.
https://www.engineersupply.com/ChrisNik-HoundDog-Magnetic-Locator.aspx
The 72 series is the least expensive on eBay. Having used the ones listed in the OP, which includes the ga-72, I suggest that either I have a sub-standard 72, or you would enjoy a different model. Or, you??ve got a 72 that??s above average.?ÿ
I used the hound dawg. It was a previous generation. It was too slow. (Slow response time, required slow sweep speed) Not good in active roads.?ÿ
How does yours do on speed?
thank you,
Nate
My favorite looks just like that one. I have used a Schonstedt (GA-52), and I preferred the ones like the picture above.
I think Schonstedt offers polarity on the Maggie and the GA-96XTd (maybe others...apparently the GA-72Cd). For me, I became so reliant on that aspect that it is hard to live without it.
I have used the GA-52 and Subsurface Instruments ML-1M models. The Subsurface came the closes to the GA-72 in function. The GA-72 has been on my truck for over 25 years and never failed me.
What's interesting is the GA-72 is about $100 more than GA-52 if bought new.
We bought one of those at the end of last year. After having to send it in for 'repairs' 3 times within a month, we got a refund and bought another Subsurface ML1. The houndog worked great until the temp dropped to 20?øF, after that the speaker would not work. That just won't do in Montana.
Those look like the do polarity as well. The ML-3S looks like a great form factor.
Edit...the ML1M would show polarity, not the ML1
?ÿ
Looked at the ML-3 some more...waterproof, polarity, tube design (which is the best IMHO)...that will probably be the next one to try.
@dmyhill?ÿ This thing?
https://www.engineersupply.com/SubSurface-Instruments-Magnetic-Locator-ML-3S.aspx
Looks nice, and I think I've actually used one of these before.?ÿ I forgot all about them.?ÿ
It looks like a great idea. I have never used a subsurface...
I know it is blasphemy, but I have never really like schonstedt for some reason.
I feel the same way.
Its the simple fact it looks like a proof of concept design for a senior project or something.
And they suck for ergonomics. But they sure as hell work.