ΑΜ radio detector

[taxma1981]

I will tell you a story from a machine that found gold in 1990.
I was told that there was a radio receiver on the ground somewhere ,another man with a small transmitter was walking opposite the receiver at a distance of 100-200 meter,
maybe there are two transmitters I'm not sure....the transmitter moves around the receiver and as the time passes it approaches the receiver,when something is found directly in the receiver and transmitter then the signal is reduced and a red light is on....in this way a box of gold was found, can a technician tell us a few words about this method?
https://ibb.co/SR5hzvh

[humhum]

Originally Posted by taxma1981

I will tell you a story from a machine that found gold in 1990.
I was told that there was a radio receiver on the ground somewhere ,another man with a small transmitter was walking opposite the receiver at a distance of 100-200 meter,
maybe there are two transmitters I'm not sure....the transmitter moves around the receiver and as the time passes it approaches the receiver,when something is found directly in the receiver and transmitter then the signal is reduced and a red light is on....in this way a box of gold was found, can a technician tell us a few words about this method?
https://ibb.co/SR5hzvh

It is very simple, the signal sent from the transmitter is reflecting from buried and moving
to Receiver , but here Receiver not is simpe Receiver !!!

[Mike(Mont)]

Maybe that guy has dyslexia? This is the whole reason why hand-held frequency locators have a hard time--the transmitter needs to stay in one place for about five minutes for the signal line to develop. Remember the signal line IS the discrimination.

Haven't seen any posts from Geo for a long time. Hope he is okay.

[taxma1981]

They did not say details so I do not know exactly how it works

[WM6]

Originally Posted by taxma1981

They did not say details so I do not know exactly how it works

This configuration could work (in fact it is very long known configuration).


Problem is, that it works with very large metal deposits only ... and.....

antenna should be as much directive as possible ... and ...

NOT directed straight toward transmitter as on those drawing, ... otherwise ...

only transmitter signal will be received and not much weaker reflective signal too.


Transmitter signal should be excluded (zeroed) by searching "from side" with

receiver antenna constantly hold at about 90 degrees to the transmitter signal.

Transmitter itself is best to be raised as high as possible above the surface.


To combine receiver with proper tuned GG AL718 antenna, would be a good solution.

This mean, you need to use stacked Ferrite core antenna (there is only one Ferrite core

antenna in commercial MW/LW receiver) to get improved directivity and more sensitivity

to reflected signal.





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[taxma1981]

the transmitter for experiments 1 watt is good or wants smaller?

[WM6]

Originally Posted by taxma1981

the transmitter for experiments 1 watt is good or wants smaller?

More watts - more unwanted mess of reflections.
Stay down till 300mW max, even 50mW of TX power is full sufficient.
Trick is in best possible antenna directivity and nulling TX signal
by "from the side" or lateral to TX signal searching.


If your multi-band radio receiver has LW (long-wave) band, use it rather than MW.
LW penetrate better. Of course Transmitter should also be working in LW band.





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[taxma1981]

thanks a lot for your reply, i have a radio that can receive a signal of 150 khz

https://imgbb.com/SyC5LcK

[humhum]

Originally Posted by WM6

This configuration could work (in fact it is very long known configuration).


Problem is, that it works with very large metal deposits only ... and.....

antenna should be as much directive as possible ... and ...

NOT directed straight toward transmitter as on those drawing, ... otherwise ...

only transmitter signal will be received and not much weaker reflective signal too.


Transmitter signal should be excluded (zeroed) by searching "from side" with

receiver antenna constantly hold at about 90 degrees to the transmitter signal.

Transmitter itself is best to be raised as high as possible above the surface.


To combine receiver with proper tuned GG AL718 antenna, would be a good solution.

This mean, you need to use stacked Ferrite core antenna (there is only one Ferrite core

antenna in commercial MW/LW receiver) to get improved directivity and more sensitivity

to reflected signal.





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''Transmitter signal should be excluded [/COLOR](zeroed) by searching "from side" with
receiver antenna constantly hold at about 90 degrees to the transmitter signal.''

Yes ,but So is when Tx and Rx Anettas is in Fix position 90 degrees , but when Rx is in Fix (without moving) and Tx is in moving position , so working method will be different.

[WM6]

Originally Posted by humhum

'

Tx is in moving position , .

Why you need TX moving?

If you use VLF (say 33kHz alike GG AL718 ) or MW or LW,
TX should be put at fixed position and RX only is moving.
In case of MW and LW, you can use existing radio transmitter
station - no need to build your own one.

If both, TX and RX, are moving, then we talk about radar (GPR),
but radar construction ask about UHF frequencies (in MHz and
even GHz band). No such radar construction is possible in VLF,
LW or MW frequency band due to long wavelength for worthwhile
antenna construction.


,

[taxma1981]

the receiver is tuned to 576 khz, the station is many kilometers away and I have my receiver straight with the transmitter, the loudest signal strength is 27 dBμ...at one point the signal drops to 12 dBμ and when I pass it and go straight with the transmitter it starts and goes up ... I think the radio does detect something, at another point nearby the receiver does not react like that.

https://youtu.be/SUyLngQESrM

[WM6]

Originally Posted by taxma1981

the receiver is tuned to 576 khz, the station is many kilometers away and I have my receiver straight with the transmitter, the loudest signal strength is 27 dBμ...at one point the signal drops to 12 dBμ and when I pass it and go straight with the transmitter it starts and goes up ... I think the radio does detect something, at another point nearby the receiver does not react like that.

https://youtu.be/SUyLngQESrM

If you are not able to zeroing transmitter signal by lateral angle of your RX Ferrite antenna
to direction of TX signal, then this approach will not work.


If you are able to zeroing TX signal, by correct angle of your antenna, then you should retain
such angle all the way during searching and not constantly changing it as on your video.


By constantly changing angle of RX Ferrite antenna you constantly get false signals.

[taxma1981]

turning the ferrite in the direction of the station you only lose the sound of the station and I hear noises, it does not completely reset

[WM6]

Originally Posted by taxma1981

turning the ferrite in the direction of the station you only lose the sound of the station and I hear noises, it does not completely reset

Probably you know wrong TX direction or it is about earth reflective signal and
not genuine direct TX signal.


It is always better to have your own control over transmitter (mean your own
local transmitter), than some distant radio transmitter with changing signal.

[taxma1981]

I will build a 500-800 mw transmitter and I would like to ask which is the most suitable antenna for the portable transmitter. 7-8 meters of wire wrapped in pvc pipe is ok?

https://ibb.co/vmFmrfG
https://ibb.co/tLhCgW9

[WM6]

Originally Posted by taxma1981

I will build a 500-800 mw transmitter and I would like to ask which is the most suitable antenna for the portable transmitter. 7-8 meters of wire wrapped in pvc pipe is ok?

It is best to use multiturn circular loop antenna.

Circular loop antennas can be easy angled to best wave propagation for your need.

Simplest way is to take plan for coil from BFO detector and use it as antenna (say about 20cm in diameter).

You ca use TX part circuit of adequate (to desired frequency) BFO detectors as Transmitter as well.

For local use full enough TX power.




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[taxma1981]

can the signal of the transmitter with this antenna pass to the ground 3-4 meters? And how far will it go approximately? I ask why I want to cover an area 600-800 meters distance and depth 3-4....My amplifier it is 800 mw

[Mike(Mont)]

Depends on soil type. Conductive ground is not good. Loose, dry sand not good. Saltwater very bad, graphite probably the worst. As for dry sand they recommend digging down until you get to some moisture before inserting the ground probes.

[abdou2014]

Originally Posted by WM6

Why you need TX moving?

If you use VLF (say 33kHz alike GG AL718 ) or MW or LW,
TX should be put at fixed position and RX only is moving.
In case of MW and LW, you can use existing radio transmitter
station - no need to build your own one.

If both, TX and RX, are moving, then we talk about radar (GPR),
but radar construction ask about UHF frequencies (in MHz and
even GHz band). No such radar construction is possible in VLF,
LW or MW frequency band due to long wavelength for worthwhile
antenna construction.


,

Thank you for help , my receiver receives the LW radio transmitter in all directions, how can I get a zero angle ???

[WM6]

Originally Posted by abdou2014

my receiver receives the LW radio transmitter in all directions,

how can I get a zero angle ???

Depend on daytime or year season LW cam be most problematic
for radio detecting use. It can reach you from different direction.

LW can travel along Earth surface, diffract on mountains and reflect
from ionosphere. Seems your position is fired by used TX frequency
from different directions. This changes during Daytime and year season.
You need to wait for best propagation or use some SW transmitter instead LW.

Probably you can get, not total zero, but some stable minimum direction. If so,
use it. If nothing help, go for SW TX.

And don't expect 800m detecting distance, in no case, Maybe, if you divide it by 100.
3m of depth on bigger metallic deposit, this is possible and real distances are about
10m at best, if your design works as it should and in ideal conditions.




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[Jeg]

Originally Posted by taxma1981

can the signal of the transmitter with this antenna pass to the ground 3-4 meters? And how far will it go approximately? I ask why I want to cover an area 600-800 meters distance and depth 3-4....My amplifier it is 800 mw

As a Transmitter you can easily use a Tesla coil grounded through a copper rod. Current oscillations move through the earth interacting with any metal in their way. Simple blocking oscillators can do the work. Look for example Kacher Brovina oscillator.

[taxma1981]

the problem is that I want to have the transmitter portable

[reza vir]

Originally Posted by taxma1981

I will tell you a story from a machine that found gold in 1990.
I was told that there was a radio receiver on the ground somewhere ,another man with a small transmitter was walking opposite the receiver at a distance of 100-200 meter,
maybe there are two transmitters I'm not sure....the transmitter moves around the receiver and as the time passes it approaches the receiver,when something is found directly in the receiver and transmitter then the signal is reduced and a red light is on....in this way a box of gold was found, can a technician tell us a few words about this method?
https://ibb.co/SR5hzvh

Treasure in its surroundings
There are many different frequencies
All frequencies that are at the same angle are merged
Here we have a new frequency that hits the treasure
The output of that variable
And it can not be properly picked up with a radio receiver
You have a lot of trouble finding
With respect

[taxma1981]

effort counts, changes will be made along the way

[WM6]

List of fixed SW beacon transmitters:


http://www.dl8wx.de/BAKE_KW.htm






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