gold gun al707 or 718

[Agraz]

swampy: Geo refers to the background reading, since there must be a high reading to be able to receive a low reading or null, I have gold gun Al707, and when I buy it from California I received here in Mexico high reading background, as 3000 mv . and when there was a null detect the reading low, (the amplifier and the meter must be used separately) but in 2003 I discovered that the ferrite antenna was broken in half, (it sounded something broken inside the white antenna) maybe that increased the reading because it received high frequencies, I returned it to accurate locators, and they put a new one and I no longer receive high reading ,,, maybe I should wind another broken (but pasted or overlapping) ferrite to try to receive frequency of about 50-100 khz, I have no idea how often I received it when it was broken, but the reading was more than three thousand milli-volts.

[SWAMPY]

swampy: Geo refers to the background reading, since there must be a high reading to be able to receive a low reading or null, I have gold gun Al707, and when I buy it from California I received here in Mexico high reading background, as 3000 mv . and when there was a null detect the reading low, (the amplifier and the meter must be used separately) but in 2003 I discovered that the ferrite antenna was broken in half, (it sounded something broken inside the white antenna) maybe that increased the reading because it received high frequencies, I returned it to accurate locators, and they put a new one and I no longer receive high reading ,,, maybe I should wind another broken (but pasted or overlapping) ferrite to try to receive frequency of about 50-100 khz, I have no idea how often I received it when it was broken, but the reading was more than three thousand milli-volts.

Well mate if you still have faith in the Gold Gun,probably the best thing you can do is try and find someone in your area with a Gold gun unit and compare his with yours.If his is giving both high and low readings like it should then I would suggest you contact Accurate locators again and tell them they didn't fix yours Properly the first time and explain to them why?

Good luck,let us know how you get on.

Cheers,Swampy.

[Geo]

Because weather these days are not good i decided to "see" my Geo Gun. I have 3..4 years to go out with it because at some frequencies it was oscillates.Maybe problem is at varicaps or at increasing of sensitivity. Also will try to supply it with Li batteries. I think that it is good for big buried objects.

Regards

[abdou2014]

HI Geo , i don't see lm324 , can we know your changes in schema ?

[Geo]

I did n't find the schematic yet. Maybe is inside the destroyed hard disk, i try to find it so to solve the problem. From what i see i use a TL071 a TLC272 and a LT?? for true RMS reading.
Also there is a 6 position selector switch so to select the right band. I change frequency via varicap.

[abdou2014]

expert parameter, I need your diagram , don't stop searching

[Geo]

Until now i did n't find full schematic...
The only that i found is the frequency selector.
Varicaps have capacitance between 20 and 500pF (if i remember ok).

[abdou2014]

thank you very much, we are missing only the receiver circuit and meter

[Geo]

Here is what i found from true rms meter.
There is n't schematic for receiver but it is the same as prototype with the difference of ic's.
I don't remember other changes...

[abdou2014]

thank you, I will try to find time for its realization I want to know does your gold gun have a good reception from VLF stations ?

[Geo]

Yes... always it receives at least one VLF station with signal more than 200mv.
As i saw at original GG when signal was lower than 150mv it was noise so no ability to detect any object.
Also is indicated only for big targets...

[abdou2014]

does it receive when the antenna is pointed towards the transmitter or in width or in both cases ?

[Geo]

I don't know who is the transmitter that it receives, i only look the meter for high signal and a narrow zero.

[abdou2014]

thanks, what is the length of each ferrite rod , wire diameter , number of turns ?

[Geo]

I use only one ferrite 20cm.
Inductance is near to 10mH per section.
Wire 0.2mm diameter
Turns... i don't remember