New detecting method?

[WM6]

0.3W?
Why nobody did it then?

Who is nobody, OKM?
Yes 0.3W is far enough.

Why OKM sell more Watts? Maybe for human vanity, you know, - "more power - more money" for OKM. And here ineffective "more power" is cheap for producer. But at the same time more power not mean more findings. Not at least by excessive power you can be quickly not only out of target but out of law too by strong widely disturbing interference. Not negligible too: by 50W of transmit power you need to bring with heavy bus accumulator to assure one day search.

This field is dedicated to art of sensitivity and harmony (resonance) not to question of power.

And probably they build antennas of very low quality - which are easy to produce but low effective antennas and try by excessive power to substitute this drawback, which is wrong approach but very profitable for producer of such things.

[g-sani]

Who is nobody, OKM?
Yes 0.3W is far enough.

Why OKM sell more Watts? Maybe for human vanity, you know, - "more power more money" for OKM. And here ineffective "more power" is cheap for producer. But at the same time more power not mean more findings.

And probably they build antenna of very low quality - low effective antenna.

No I am not talking only about OKM WM6.
First I thought the ones they make feed the signal straight into the ground.Somebody else told me that you just put the aerial on the ground.This is how it looks in the photo anyway.Check the last line of the characteristics.Only 10 meters? Is it "maximal sphere of action" the effective range or something else?

Features of the Control Unit

Operating Temperature: 0 °C – 50 °C
Storage Temperature -20 °C – 60 °C
Air Humidity: 5 % – 75 %
Waterproof: No
Dimensions: 25H x 22W x 17D cm
Weight: about 7.4 kg
Frequency Range: 7 kHz - 60 kHz
Amplified Output Power: 10 W
Internal Battery: 24 V
Operating Time: (full charged battery) about 3 h
Charging Time: about 10 h
Maximal Sphere of Action: about 10 m

[WM6]

Check the last line of the characteristics.Only 10 meters? Is it "maximal sphere of action" the effective range or something else?

Frequency Range: 7 kHz - 60 kHz

Maximal Sphere of Action: about 10 m

Yes, low effective antenna, nothing else. Maybe without such antenna only by resistive end you can reach the same "Sphere of action". Those antenna act only as TX output load to prevent Tx damage not as real and effective VLF/ULF antenna..

It is understandable that no one can build effective resonate antenna for wide Tx range of 7Khz to 60kHz. Practically impossible.

And why one need such wide frequency range? This is not working on VLF/IB or BFO principle where are some differences in detecting between frequencies. Here not, except partially in the immediate vicinity of target, but we are asking for some remote detecting. Here you need only one frequency say between 10-30kHz and resonate Tx and Rx antennas to selected frequency and as good as possible directivity of Rx antenna.

[J_Player]

Hi J_P
Don't you think that 5m depth is enough?
I think it is.
The best for me is a handheld device for a radius of 200 meters.
I know I am asking too much.

Yes,
I think less than 5 m deep is what most treasure hunters are usually looking for unless they suspect there is a worthwhile treasure deeper. Many treasure hunters would be happy to have a detector that can locate a buried treasure 2 m deep from a radius of 200m.

There are geophysical instruments that can locate metal things at this depth and also over 5 m. But these are not hand-held locators that you can put in your backpack and expect them to point the direction of a buried treasure. They are used to perform surveys of an area that is plotted so the data shown on maps can be analyzed by a geologist to determine what is under the ground. VLF signals that geologists use are transmitted from large VLF beacons all over the world. They receive these beacon signals between 1-30 KHz, and can collect data up to 25 m deep in the ground, and sometimes deeper when holding a loop receiver antenna in their hand to pick up the distant transmitter signal.

But if you are looking for shallow anomalies at less than 5 meters, then you can raise the frequency up to 150KHz for better resolution in your survey. The large military VLF transmitters do not use ground probes for a transmitter antenna. They have a large arrays of antennas in the air. Geologists use ground probes to measure the ground resistivity and induced polarization, which are electrical measurements, not RF. The idea that you can get efficient wave propagation in the ground by using ground probes does not sound correct to me.

In order to use a small portable transmitter, I agree with WM6, that a small air core loop will probably work the best. From what I can see WM6 is very knowledgeable in how to make an efficient VLF transmitter, and probably understands the near field propagation and ground absorption better than someone who tells you it can be done best with putting probes in the ground.

Best wishes,
J_P

[J_Player]

Hi J_P
Don't you think that 5m depth is enough?
I think it is.
The best for me is a handheld device for a radius of 200 meters.
I know I am asking too much.

Yes,
I think less than 5 m deep is what most treasure hunters are usually looking for unless they suspect there is a worthwhile treasure deeper. Many treasure hunters would be happy to have a detector that can locate a buried treasure 2 m deep from a radius of 200m.

There are geophysical instruments that can locate metal things at this depth and also over 5 m. But these are not hand-held locators that you can put in your backpack and expect them to point the direction of a buried treasure. They are used to perform surveys of an area that is plotted so the data shown on maps can be analyzed by a geologist to determine what is under the ground. VLF signals that geologists use are transmitted from large VLF beacons all over the world. They receive these beacon signals between 1-30 KHz, and can collect data up to 25 m deep in the ground, and sometimes deeper.

But if you are looking for shallow anomalies at less than 5 meters, then you can raise the frequency up to 150KHz for better resolution in your survey.
The large VLF transmitters do not use ground probes for a transmitter antenna. They have a large arrays of antennas in the air. Geologists use ground probes to measure the ground resistivity and induced polarization, which are electrical measurements, not RF. The idea that you can get efficient wave propagation in the ground by using ground probes does not sound correct to me. When geologists do want to transmit their own VLF signal, they lay a cable down on the ground in the form of a large loop maybe 1km diameter, then use their hand-held receivers to survey the area around the loop.

In order to use a small portable transmitter, I agree with WM6, that a small air core loop will probably work the best. From what I can see WM6 is very knowledgeable in how to make an efficient VLF transmitter, and probably understands the near field propagation and ground absorption better than someone who tells you it can be done best with putting probes in the ground.

Best wishes,
J_P

[g-sani]

Thank you J_P, I can undrestand that WM6 knows better the subject.
So what do you think it is best to use whith my gold gun?
Is it a necessity to transmit in exactly the same frequency as we receive?
Do you know if there is anything ready to be used in the market?

[g-sani]

Yes, low effective antenna, nothing else. Maybe without such antenna only by resistive end you can reach the same "Sphere of action". Those antenna act only as TX output load to prevent Tx damage not as real and effective VLF/ULF antenna..

It is understandable that no one can build effective resonate antenna for wide Tx range of 7Khz to 60kHz. Practically impossible.

And why one need such wide frequency range? This is not working on VLF/IB or BFO principle where are some differences in detecting between frequencies. Here not, except partially in the immediate vicinity of target, but we are asking for some remote detecting. Here you need only one frequency say between 10-30kHz and resonate Tx and Rx antennas to selected frequency and as good as possible directivity of Rx antenna.

I know that my gold gun AL707 receives in 19.6khz and also in another two lower freqs but how can I accurately measure the frequency myself WM6?
I think I have to verify the receiving frequencies myself first before I will see about the transmiter.
Thanks for helping.

[J_Player]

Thank you J_P, I can undrestand that WM6 knows better the subject.
So what do you think it is best to use whith my gold gun?
Is it a necessity to transmit in exactly the same frequency as we receive?
Do you know if there is anything ready to be used in the market?

Hi g-sani,
I have never used any hand-held detector on the market that was able to locate buried metals for me at a long range more than about 1/2 meter, or maybe up to 2 meters for very large metal things when using a VLF loop. I only hear stories that other people say there are locators that can find buried metals at long range.

I have no way to know if a Gold Gun is best for you to use. If you can find a gold gun, then you could check to see if it is locating buried metals for you. If you find it helps you to find buried treasure, then you will know whether you should use it or not.

From what I understand, the gold gun is a receiver without a transmitter. I have no idea of what RF or electronic principle it uses to locate buried metal. But if it is only receiving RF, then it could be looking for the strongest signal strength, or it could be looking for some specific kind of modulation or interference at the frequency it is tuned to. I have no way of knowing because I don't know what the circuit electronics are designed to detect.

One thing I can tell you that if it is an RF receiver with added signal processing circuitry and no transmitter, then it is designed to receive RF signals from a distance, not from a transmitter at close distance from the receiver. If you were use a small transmitter at your hunting site, then the signal coming from this transmitter will be broadcasting RF in the near field, whose propagation properties are not the same as transmitters far in the distance. You will find that the field strength and radiated power pattern does not follow the math formulas that are used to determine what that signal will be if it came from a distant transmitter. But at least any modulation you send from a nearby transmitter will be preserved in the near field area.

If you want to know more about how to actually build a transmitter and receiver, I would recommend that WM6 is very knowledgeable about this, and probably has more experience and knowledge than most people in this forum.

Best wishes,
J_P

[g-sani]

Hi J_P
Once many years back a friend of mine gave me a gold gun al718 for a month to see if it can detect anything or not.
There was a single page inside its box roughly explaining its operation.
All I paid attention then it was a part saying that if the pistol like detector was pointed to a precious burried target goes silent.
I discovered some guns from the 2nd world war once from about 50 meters and some other time it was 5 or 6 bullets spread close to each other but only 15cm deep.I was surprised to see that it was easy to go on target.
The gold gun has a digital voltmeter giving different readings as you sweep it from side to side apart from the amplified audio signal in the speaker.
I didn't use it many times to say the truth but I could tell whith the experience I had those days that this pistol could detect something.
This is how and why I got my goldgun later on from a shop that was closing down in States.I bought it for much less money than what Accurate Locators used to sell it.
I discovered later on that probably this type of lrl doesn't work any more since most of the VLF stations arround Greece closed down.
Some other users here in Greece say that there are some emmisions in certain days but thats not a solution for me.
Even accurate locators made a Tx later and started selling it again until it was for some reason discontinued.
So I am in position now looking for a Tx to duplicate the emf fields of the old days that don't exist now.
But the truth is I always leave it behind J_P because I can not reach to a right conclusion of what is best to do.

I can put photos down of the cct or the pistol itself but I think somebody put some already in the forum under some other thread.

[WM6]

I know that my gold gun AL707 receives in 19.6khz and also in another two lower freqs but how can I accurately measure the frequency myself WM6?
I think I have to verify the receiving frequencies myself first before I will see about the transmiter.

I don't know what of instruments do you have in your lab.

If you start from "Gold gun" which is real for you, you need first to measure all of (as you say) three frequencies of your AL707. Do not believe to producers data it may vary, but because of ferrite antenna ("widest" Q) real data can be inside of acceptable tolerances.

There are some way to measure antenna resonance but first rule have to be that we may not to over-burden input LC circuit by direct measure instrument connection in a way to change his resonate frequency.

So we will try to measure without to over-lasting antenna circuit. Maybe you have or can lent some sort of reliable audio signal generator or signal generator for general use. If so, you first wind your testing transmit antenna from about 10 turns (1mm Cul) 10cm in diameter (or 10 turns on ferrite rods) and connect such testing antenna together with serial connected 1k pot (trim to middle position) to generator output. Put generator output on unloaded (max peak to peak output) square signal (typically 15vpp). Now you have your testing measurement transmitter ready.

Put your AL707 "ON" and approximate it to test antenna at about 20cm. Now you start to gradually change generator frequency from 0Hz to about 35kHz and watch for react from AL707 speaker or led. If you catch signal, try to establish his maximum. Frequency at which signal reach his peak is resonate frequency of selected frequency position of your AL707. Try the same way to establish other two frequency. In case of strongest signal from receivers speaker you can use attenuator on signal generator to get weak signal or put AL707 so apart from TX antenna to get weak signal from speaker. By weak signal we can more accurate establish peak and by this more accurate resonate frequency too.

In case of no signal from AL707 you can first regulate serial pot to lower resistivity of about 100E, more approximate test antenna to AL707 and at the end try to open it and measure signal at amplification stage by mV-meter or scope. To prevent possible damage hope that this would not be needed.

After you establish all three of antenna circuit resonate frequencies your next step is transmitter adopted to middle of three frequencies (or on one of his lower harmonics).

Here may you suggest to buy very usable testing instrument Portable frequency counter with possible use as field strength meter. You can search for it on eBay under name "GE FC-1 Portable Frequency Counter 10Hz - 2.6GHz". Usable to detect in-depended of transmitter and receiver resonate frequency of TX antenna and cheap.

[J_Player]

Hi J_P
Once many years back a friend of mine gave me a gold gun al718 for a month to see if it can detect anything or not.
There was a single page inside its box roughly explaining its operation.
All I paid attention then it was a part saying that if the pistol like detector was pointed to a precious burried target goes silent.
I discovered some guns from the 2nd world war once from about 50 meters and some other time it was 5 or 6 bullets spread close to each other but only 15cm deep.I was surprised to see that it was easy to go on target.
The gold gun has a digital voltmeter giving different readings as you sweep it from side to side apart from the amplified audio signal in the speaker.
I didn't use it many times to say the truth but I could tell whith the experience I had those days that this pistol could detect something.
This is how and why I got my goldgun later on from a shop that was closing down in States.I bought it for much less money than what Accurate Locators used to sell it.
I discovered later on that probably this type of lrl doesn't work any more since most of the VLF stations arround Greece closed down.
Some other users here in Greece say that there are some emmisions in certain days but thats not a solution for me.
Even accurate locators made a Tx later and started selling it again until it was for some reason discontinued.
So I am in position now looking for a Tx to duplicate the emf fields of the old days that don't exist now.
But the truth is I always leave it behind J_P because I can not reach to a right conclusion of what is best to do.

I can put photos down of the cct or the pistol itself but I think somebody put some already in the forum under some other thread.

Hi g-sani,
The way you describe the performance of the gold gun sounds similar to a radio direction finder. It sounds like it works by tuning the VLF signal from a distant transmitter that is no longer transmitting. How it can detect buried guns, I don't know. But if it needs a VLF signal to work, then this would explain why there were VLF transmitters manufactured to make a new VLF transmission after the VLF transmitter was shut down.

From what you posted, I would think you first need to determine what frequency the gold gun is tuned to (I think I remember it is somewhere around 60KHz). You may be able to send an email to the company that sold the transmitters, and ask what frequency they are. Then you could build a transmitter that sends a VLF signal at this frequency to put near your treasure hunting area. I think WM6 can give some good information on how to do this.

Best wishes,
J_P

[Qiaozhi]

The Gold Gun has 3 ranges:

1. 9.5KHz for long distance and weak EM fields.
2. 26.7-27KHz for USA.
3. 19.2KHz England, Philippines, Greece and USSR.

Or so they claim.

[WM6]

If you were use a small transmitter at your hunting site, then the signal coming from this transmitter will be broadcasting RF in the near field, whose propagation properties are not the same as transmitters far in the distance.

Yes, but huge changing in propagation (like changing wave polarization etc) are in first line characteristic of very high frequency band as UHF not in VLF/ULF band. By local small transmitter we find some others aspect of problem. We are searching for weak source of reflected signal and at the same time we have in vicinity relative strong source of transmitted signal at the same frequency which cover weak target signal and disturb successive search . This is why I repeated that 0.3W is far enough and even too much for successive search. This is why we need as much as possible directive RX antenna to suppress direct TX signal in combination with some tricks and searching skill.

If we compare UHF and ULF frequency band from reflectivity view UHF are better to detect especially small target in air because of its directivity and worse to detect something underground because of his weak penetration ability, on other side ULF are weak on directivity and so worse to detect something in air but way better to detect something underground because of his excellent penetration ability in soil. Theoretically ULF radar can detect invisible objects (objects behind of hills or behinds of horizon) which UHF radar cannot. This is why ULF can reach targets on unusual way and why we speak about importance of RX sensitivity and Rx antenna directivity.

[g-sani]

I don't know what of instruments do you have in your lab.

If you start from "Gold gun" which is real for you, you need first to measure all of (as you say) three frequencies of your AL707. Do not believe to producers data it may vary, but because of ferrite antenna ("widest" Q) real data can be inside of acceptable tolerances.

There are some way to measure antenna resonance but first rule have to be that we may not to over-burden input LC circuit by direct measure instrument connection in a way to change his resonate frequency.

So we will try to measure without to over-lasting antenna circuit. Maybe you have or can lent some sort of reliable audio signal generator or signal generator for general use. If so, you first wind your testing transmit antenna from about 10 turns (1mm Cul) 10cm in diameter (or 10 turns on ferrite rods) and connect such testing antenna together with serial connected 1k pot (trim to middle position) to generator output. Put generator output on unloaded (max peak to peak output) square signal (typically 15vpp). Now you have your testing measurement transmitter ready.

Put your AL707 "ON" and approximate it to test antenna at about 20cm. Now you start to gradually change generator frequency from 0Hz to about 35kHz and watch for react from AL707 speaker or led. If you catch signal, try to establish his maximum. Frequency at which signal reach his peak is resonate frequency of selected frequency position of your AL707. Try the same way to establish other two frequency. In case of strongest signal from receivers speaker you can use attenuator on signal generator to get weak signal or put AL707 so apart from TX antenna to get weak signal from speaker. By weak signal we can more accurate establish peak and by this more accurate resonate frequency too.

In case of no signal from AL707 you can first regulate serial pot to lower resistivity of about 100E, more approximate test antenna to AL707 and at the end try to open it and measure signal at amplification stage by mV-meter or scope. To prevent possible damage hope that this would not be needed.

After you establish all three of antenna circuit resonate frequencies your next step is transmitter adopted to middle of three frequencies (or on one of his lower harmonics).

Here may you suggest to buy very usable testing instrument Portable frequency counter with possible use as field strength meter. You can search for it on eBay under name "GE FC-1 Portable Frequency Counter 10Hz - 2.6GHz". Usable to detect in-depended of transmitter and receiver resonate frequency of TX antenna and cheap.

Thank you very much for your help WM6.
The only thing that I have to ask you to explain me better is:

....After you establish all three of antenna circuit resonate frequencies your next step is transmitter adopted to middle of three frequencies (or on one of his lower harmonics). ....

Do you mean that if the lower freq. is 9khz and the higher is 10khz then the Tx must be adopted at 9.5Khz?

[J_Player]

Thank you very much for your help WM6.
The only thing that I have to ask you to explain me better is:

....After you establish all three of antenna circuit resonate frequencies your next step is transmitter adopted to middle of three frequencies (or on one of his lower harmonics). ....

Do you mean that if the lower freq. is 9khz and the higher is 10khz then the Tx must be adopted at 9.5Khz?

Hi g-sani,
Look what Qiaozhi posted:

The Gold Gun has 3 ranges:

1. 9.5KHz for long distance and weak EM fields.
2. 26.7-27KHz for USA.
3. 19.2KHz England, Philippines, Greece and USSR.

From this information, you need only one frequency for Greece to find the same VLF frequency you saw before.
19.2 KHz is the oscillator you want. This is much simpler than to build a variable frequency oscillator, and the antenna can be tuned for this frequency so it will send a strong signal at low power. Of course, you will want to make adjustments to find the exact tuning that gives good reception at your gold gun. See the WM6 post for this.

You could also build a transmitter that sends all 3 frequencies if you think this will help.

Best wishes,
J_P