Sign in to follow this  
Followers 0
Jim Straight

Fisher Two-Box High-Voltage Vacuum Tube Metalloscope

15 posts in this topic

Just out of curiosity Jim - why are you interested in one of these?

We can still talk about them. I've seen pictures but never seen one in operation and I am interested how they work.

Cant be many of these out there still in fully functional, operational condition. I'm sure a few, but not many.

First Texas may have one on hand as a museum specimen.

Share this post


Link to post
Share on other sites

Chris... to cut to the quick... I acquired a vacuum tube two box that originally

belonged to the Utah State Collage and was sold as surplus.  It was

manufactured in 1946 and used high-voltage batteries to drive 5-vacuum

tubes...   It is a direct descendent of Dr. Gerhard Fischer (Fisher) original 1931

Metallascope and patented in 1937. With the development of Transistors in

the 1950s; it became known as the Fisher M-Scope Gemini-series.

My vacuum tube two-box used large-size, heavy and cumbersome high

voltage batteries. But depth it had, and I was able to detect magnetic black

sands at depth. Black sands are often associated with placer gold if in a

metalliferous area..... Also the two box could be useful to trace out

condictive metals.... Unfortunately the batteries we now expensive and

the vacuum tubes in high-power drain them fast. So I used it spairnly  

and they were special order in a cardboard rectangular box with a short

shelf life. One box was the transmitter and the other the receiver..jim

Share this post


Link to post
Share on other sites

Do you think the older vacuum tube type had an advantage over the newer transistor versions?

Or were the transistor versions of the two box about the same, just running on a lower voltage system?

Share this post


Link to post
Share on other sites

Jim,

Why don't you use a Discovery TF-900. It uses 6 AA batteries with an estimated life of 20 hrs.

It has "All Metal" mode with ground reject, and a TR Cave Mode that responds to no or low mineralization.

It had a depth capability of 15-20 ft on a 50 gal barrel and 20-30ft on a car, to the best of my relocation.

 

I also use an ArcGEO Logger to record the grid responses to use on a laptop to display the data.

 

I have never used it on these targets, but used the 73khz Pipe Finder circuit to locate water lines at 4-8 ft. It uses a separate transmitter and different coil to find pipes. If you get good you can even accurately estimate the depth, by using the 45 deg response technique.

 

A Better method to MAP Black Sand deposits is the Hand Held Magnetometer, an inexpensive model that should be adequate is the Flux Gate Magnetometer by Carl Mooreland at the GeoTech Site.

 

Another method would be to use Induced Electrical Current sensing system, ie Electrical Resistivity.  It is accurate to Hundreds of Feet, and will give you a color map of the deposit if you use ResDev 2d or 3d software

 

These can all be researched on the GeoTech website.

 

Sincerely

Bill "Lost Adams"

Share this post


Link to post
Share on other sites

Bill you are correct; but still do not count out the Gemini 3 for locating and mapping blacksand

concentrations; but back when I was using the Vacuum tube Metallascope it used large  high

voltage batteries to power up the tubes and as you know there are still advantages the tubes

have over transistors and I punched down deep and if in a metallogenic area the blacksand

was most likely associated with placer due to its gravitational association.

 

Changing the subject if you are lost adams Bill you could be looking on the wrong area. But I have

no idea where it is; just where it ain't...    jim

Share this post


Link to post
Share on other sites

ICMJ Associate Editor Chris Ralph:

 

(Chris, I mailed you a photo of me using my 1946 vintage Fisher Metallascope

as my photo on this forum... I would be most appreciative as I can no send

photos. It is legal.  George Shields took it and Chris Gholson  gave me permission

to use it; ref pg 139 in his co-authored Rich Hill)

 

I did pretty good with this vintage/obsolete vacuum tube type that needed expensive

high-voltage primitive carbon type battery packs that were needed

to drive the 5-tubes two-box deep... yards (feet)...  not inches into the sub-soil

formation while seeking a conductive hard rock vein, that I failed to find

 

I was most successful in locating  large concentrations of magnetic black sands

that are often associated with placer (gold,electum,silver) deposits due to both

having a higher specific gravity... Depths 3 to 6+ feet; usually on a caliche, hardpan

or other bedrock. For a buried 50 gallon drum up to 10 ft or more; but who in their

right mind would spend the effort to dig a deeper hole unless it was tossed into a

vertical shaft.  

 

For  treasure hunters My original metallascope was NOT senitive to raw metal less in

size as a trashdump of buried cans that were into a shallow shaft up to say 9-ft deep.

 

But the Fisher Gemini 3 is great to locate a can or even a saddle-pouch of buried loot.

Quart size canning jars filled with coins been said to have been found at posthole

depths of three to five feet...

Share this post


Link to post
Share on other sites

Jim, the "Lost Adams" moniker is from my different Names and pursuits

My name is William V. Adams

I hunt and Find Lost gold mines and treasures.

I spent a good bit of time researching the "Lost Adams Mine" on the Border between Arizona and New Mexico.

I do Admit I have NEVER been LOST in the Boonies.

At times I have been a mite bewildered as to where I was though. Only when I was much younger though, Not Recently!

If you look on my Facebook page or my LinkedIn page you can see the Pic of me Looking Lost.

couldn't figure out how to post a pick here???

  As far as the Lost Adams Mine is concerned I believe that it is at or very near the Ancient Apache Chiefs burial grounds, where ever that is. I personally wouldn't go near the area, even IF I knew where it was, as I believe it is Guarded by a Warrior or two that aren't bound by anything except Ancient Tradition. Hence IT NEVER Being found in modern times. And If you do you never LIVE to tell the Story.

 

Sincerely

Bill "Lost Adams"

Share this post


Link to post
Share on other sites

 Thanks Chris... It sure looked like I needed to diet... camera angle :rolleyes: :rolleyes:....

 

Bill, I reckon the lost adams is named because it is lost... But You are not

lost; thus I sense you have a couple of great stories to relate if you have

a mind to do so. And for sure I would be delighted to read one.    

Share this post


Link to post
Share on other sites

Chris my Vacuum tube two box needed a dry-cell in both the transmit and receive box.

Each drycell Rayovac BA-51 were 67.5 volts and lasted about 9 hrs. It used highvoltage

and punched down deep... as far as raw depth about as good as the Gemini-3 but mine

lacked the refinements of the later transistorized Gemini's.

 

But I have quite a story to relate... but I struggle to write a good article; but it could be

a good article... jim 

Share this post


Link to post
Share on other sites

Bill If seeking for lost gold mines and treasures is what you like

to do; go for it. You could find it while others miss. And it could

be in the cards you will be even if you miss the one you are

seeking; you could find a heretofore overlooked one.

Share this post


Link to post
Share on other sites

Over the recent years I have noticed more interest in two-box detectors. Since the

receiver and transmitter searchcoils are separated, their depth capabilities are to

be measured in feet instead of inches. They work because they measure the changes

in conductivity under the receiver "box." Their depth depends on the mineralization

of the soil and the size and shaped of the conductive soils.   

 

Back about 2010 on another forum I was bashed by claiming depthjs of three or more

ffeet to locate concentrations of placer gold.within the metaliferous dry south-westerm

deserts. The method is smple, just  use a two-box to seek concentrations (pockets

and channels) of magnetic black sand; but to be fair, as I did not mention I was using

my vacuum-type two-box instead of a conventional detector and being ruthlessly

bashed I picked up my marbles and that was that. 

 

However I was using this method....  crude I will admit, but by virtue of free-milling placer

and magnetic black sand being "bed-fellows," I was able to trace-out magnetic black sand

concentrations that carried eluvial placer deposits. Like a bolt out of the blue, I

became aware of the relationship of regional geology to the types of placer deposits.

 

More later, I got a lota backyard cleanup to do and I is slow as I use a walker; but it is

great to be out and about...Off subject... Hey, Chris if all goes well I will be in the Valley

Prosepectors booth at GPAA gold and treasure show n Pomona Febr. 20-21 and looking

forward to seeing you and your dad... jim 

Share this post


Link to post
Share on other sites

:DI picked up a Bounty Hunter TimeRanger and discovered that it does pickup black magnetic sands when looking for gold in all metal mode , I know most people think a Bounty Hunter just junk but this unit is not , I own a number other detectors from different companies and none of my other units will do this , I ground balanced it and started searching and it started going off with a faint signal and irregular pattern and I was thinking to my self what a heap , so I ground balanced again and again , that is when I started to dig up the small signals and found out the detector followed the outline and center of the black sand deposit in all metal mode , I tested this about 20 times now and it always finds the gold , because I have some very fine placer flood gold here and the eddy currents and beach topography determine where the gold finally lands and it is in the black sands 99% of the time , I am already on a large inside corner of a gold bearing river , sometimes I end up with just black sands and no gold but that is why you take your pan and screen along to sample and see what is in the area you want to work !!! If you find a good deposit bring out your high banker  and start moving some yardage !!! :)

Share this post


Link to post
Share on other sites

I have picked up large objects, a smashed Cadillac hub cap at 3 feet deep in all metal mode with my Bounty Hunter Pioneer 505 , right after my Whites TDI battries  died , I brought the 505 as a backup and I have hit some extremely deep targets with my BH TimeRanger in all metal mode a small fence post at 2 feet , the two box detectors will go very deep but it has to be a large object like an airplane or a car or a 50 gallon drum my Garrett GTI 2500 with a two box hits some extreme depths !!! 10-25 feet !!!

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!


Register a new account

Sign in

Already have an account? Sign in here.


Sign In Now
Sign in to follow this  
Followers 0