Does My 705 Need A Tune-up?

[Old Longhair]

I'm a tad concerned that there might be something amiss with my 705. With increasing regularity, it indicates rusty bottlecaps as good targets. High, clean, clear tones combined with steady ID's of 38. 40. 42, 44, and even 46. No broken tones or warbles. No ID fluctuation. More common with the 7.5kHz DD than the 3kHz concentric.

Now I understand that ground chemestry plays a part, and that segment bin widths are not as big on the high end with the 7.5 as they are with the 3, but at this point I can't even contemplate how bad it would be if I strap an HF coil on it.

I had it out today with the 7.5 at a park that I've hunted a lot. Ground there varies some, but not too bad for around here (it was fairly wet, but not muddy). Phase numbers tend to be in the upper 20's to low 40's. I only dug solid tones, with stable ID's, that were checked from at least two directions, and still dug a TON of rusty BCs. I even tried switching to Prospector mode w/Iron Mask turned all the way up, and they still showed as legit targets.
I'm starting to lose my mind over this. And FWIW, I did a factory reset.....no change.

So what say ye? Do I send it in for a checkup? Should I call ML and see what they recommend? Is there a good posibility that there is a firmware upgrade in existance that I could benefit from? HELP!!!

 

[DirtAngler]

My 705 does the same thing but I'm pretty sure it always has. I had the same thing with the Etrac. I think it just depends on the composition of the bottlecap along with other factors. Be interesting to hear from others, including Digger and Morelic.

 

[TURNMASTER]

I only have that problem when there are bottle caps where I am hunting!

That being said I can now tell the difference between a BC and a coin based on sound. That is with the 10.5 MF DD. The coin tone is less harsh and the BC has a slightly higher pitch, even in 4 tones. I still dig them though because sometimes corroded coins sound similar to my ears. I am going to run the HF coil tomorrow and expect to dig a bit more iron. I have a local park that I have hunted a few times and I avoid one of the ball diamonds because it is infested with caps.

Jeff

 

[GTzer]

Still learning this 705 and I have the tune-up come to mind for several issues.

28 yrs with a Whites analog- BC's: I was able to eliminate a majority by increasing the disc when I located one of those iffy (BC) type signals. There were always some that I could not do this and would have to dig. I always thought that the "halo" explanation was the reason.
Each area had its own type of anomalies with BCs. ie-certain places that type of target would not read as concentrated a blip when pinpointing----it would be slightly less defined. Once I did 4-5 of these at a certain site- I could 90% eliminate digging this target.

What I will do eventually with this 705---for any given area--I will notch out this type of signal---delete that function when I'm done-and use this function when ever I have the same problem with my next chosen area. In effect your just checking the signal against a notch that you have chosen for a specific area. If you're hunting in AM or pattern 1 do this notch on say-pattern 4 and use it as a check.

Also- try going over the target once you have removed a small plug- many times you will get a more accurate signal once you disturb the halo.

 

[Digger]

In my opinion, two words........ wet soil! At least that is what I find with all my detectors. One thing you might try that seems to work fairly well for me....... using Pinpoint sizing or the Prospecting mode, evaluate the size of the target compared to what a coin of that same TID would register. If the bottle caps are over 6 inches deep, all bets are off. But what I've found on bottle caps less than 6 inches is that (prior to breaking the ground matrix) the iron oxide leaches out into the ground, creating a target size that is substantially larger than that of a coin. I also believe that those old bottle caps chime in with a sharper audio hit than coins generally do. More of a BANG than the smooth audio tone of a coin. JMHO HH Randy

 

[Old Longhair]

Thanks for the responses.
I'll stick with it a while longer before I do anything else. Just that we had one of the wetest years on record last year, and only twice all year did I encounter anything like this. Now I've run into it twice in the last week, at one location that I'd never been to, and at one site that I go to often. If the box is gremlin free, then I have to hypothesize that the actual chemical makeup of the soil, coupled with the wet is part of the equation contributing to the problem. I guess that time will tell.

It also raises the question, "Would an E-Trac or Explorer SE, or any other machine that reads CO and FE separately, do any better at interpreting the target in these situations?"

 

[Mark in S.E. IA]

Longhair, Welcome to the DD 7.5 coil, it loves rusty BC's, lol. one way to tell if it is a BC when using the DD coils but not always is to wiggle the coil and drag it back towards you. watch the numbers and just before the tone cuts out the numbers should drop below 30 and if the numbers drop off 90% of the time it will be a BC, BUT now always. The other 10% of the time when the numbers drop off it could be because their is a nail or BC close to the Quarter. Their is other ways to tell if it's a BC but the wiggle is the best way.

Today I went back to a one room school house / farm field that I was workin this weekend. I get over the fence and turn on the Mder and was looking for a clean spot to GB and I get a screaming #42. the way the tone was told me it was a BC but I dug it anyhow since I was in a farm field and I'm glad I did, it turned out to be a AU-50 1920 SLQ That was one of those 10% that sound like a BC but it wasn't.

 

[EOS]

OK!..wet soil ,maybe thats why my 705 with 7.5DD been acting weird,with a lot of false signals.Was thinking I got another bad 10.5 as they replaced the first one.Funny though, it has not happen when I walked over the same place
with the no,no-coil....but thats another frequenze.

I do also pick-up BC

 

[bugg]

I rarely did a bottlecap with my safari. I think the fbs machines have the finest discrimination system on the market. Now if they could just get the weight down..

 

[chuckciao]

I can't tell you how many sweet 42 and 44 TID's I dug only to find a rusty bottle cap!

 

[Mtnmn]

The problem with bottle caps is that they are made with a wide assortment of alloys and plating's, not to mention their rust content can help fool not only the 705, but almost every brand of detector on the market. So what you are experiencing is not all that unusual at all and it is doubtful if there is anything wrong with either your detector or coil. With experience you will find yourself digging less and less trash (ie. bottle and screw caps) as time goes by. Watch closely on how your numbers react to quarters and then on trash such as bottle and screw caps, there are very subtle differences between the two. I hunt a lot of camping sites and a tarp grommet will still fool me just about every time out.

 

[Old Longhair]

I dig a few grommets too, but that doesn't disturb me. And under most circumstances I've been able to distinguish bottlecaps from good targets, primarily by sound. But just recently, and at places that I hunted before, they've suddenly become a problem. That is what prompted my initial question. And about all that I can surmise is that the now nearly saturated ground is playing a huge roll. Perhaps numberous freezings and thawings along with the wet has created an abnormal halo. I was at another site yesterday where copper memorials were comming in @ 40-42, instead of the more normal 38. Yet, the small sterling religious pendant that I dug still rang in @ 44 as expected.

 

[TURNMASTER]

I was digging Lincolns at 42 last weekend too. I find that I get a better ID with a little less Sensitivity. Ground here is wet.

Jeff

 

[EOS]

Ground is soaked here. I have also lowered the sensitivity down to 19-21.Much better, more stabil.
Copper coin goes in at 44-46 and have a sweet tone.

Mike