IDX-PRO+VDI

[golfnut]

As silver dollar says, its a bit of a suck and see. Thats what I did with the nel Hunter and got lucky.

If you can borrow some coils from a club and make adapter plug/socket to enable a trial. Or get a loan from someone on here.


making them is fun if your practical and have the time and kit - not for everyone I realise.

[ampirate]

Somewhere, I remember reading about Custom Coils done by somebody/website ...

- Does anybody know of such, who builds IDX Pro Coils ?

[Silver Dollar]

Until you try it you won't know. If each coil was pure inductance changes can be made on the pcb.
If caps are inside the coil it is difficult to change the frequency and might not work with your TX
oscillator. If it needs the coupling resistors like some White's it is unlikely to work unless it is a White's.

I just got an old Bounty Hunter ID 505 for $7 at the flea market it has 2.56 mh TX and 8.67 mh RX but
the TX will not work with my oscillator. So I have to open the coil and remove the TX cap or make a
different oscillator...

[ampirate]

Thanks,

My question is though, what about the Coils with the same 6KHz-7KHz Freq from other Vendors ?

* Rutus Argo 9.5x8in or 11in DD 6.6KHz Coil
* Mars Tiger 9x12in 7KHz Coil
* Minelab Xtera 7KHz Coils T305 / T505 / T705
* Coiltek 15in DD 7.5KHz

[golfnut]

Ive mucked about like this and you canbend these things into shape - often annoying tho.

There is a list of requirements

Almost all of these coils will not be plug and play. You must be prepared to change Cap values here and there and it is a fiddle.

Getting the phase relation of the Rx signal wrt to Tx signal correct so the groung can be nulled ( test with ferrite ). Wanted alloys accepted
(If you get double beep you must flip Rx coil terminations in the head )
Tx has a clean large signal ~15Vpp decent sinusoid. ( creates 1 Tx freq rather than a forest of spurs )
Rx preamp output not too large - reasonable null - doesnt have to be perfect ( doesnt saturate preamp over targets )
Rx front end resononance frequency about 75% of Tx frequency ( gives depth without too twitchy )


Dont stray too far from normal freq as the RC phase shifters may have too much or too little phas shift, I modelled 12kHz in spice and stock build worked well. ( my IDX was 12kHz Tx ) I use a nel hunter for a Tejon (14kHz on the Tejon )

I made C32 smaller to recenter the preamp a little higher, this only gave a couple of dB lift - probably not needed?


I did similar work on a ace 250 and made it 14kHz - Changed Tx and Rx cap in box - I had double beep on good targets, but I had ferrite reject. To fix I inverted the preamp output using a unity gain inverting buffer opamp, so -180deg. Simulates flipping the Coil wires in the head, worked real well.

[Silver Dollar]

Well on the Bandito (10 khz) I was able to use the Tracker Coil (6.6 khz) but had to remove the
TX cap in the coil housing and change a TX cap and the RX cap. I am now running it at 12.5 khz.
( Tracker Coil - TX 2.7 mh RX 2.4 mh Original Bandito Coil - TX 6 mh RX 6.5 mh)

The problem is that White's coils typically cross couple the RX and TX with caps and resistors in the coil.
So you might need to mess around with that coupling on the new coil....

http://www.geotech1.com/forums/attachment.php?attachmentid=27297&d=1385260803

[ampirate]

Would these Coils be compatible with the IDX Pro ? :

* Rutus Argo 9.5x8in or 11in DD 6.6KHz Coil
* Mars Tiger 9x12in 7KHz Coil
* Minelab Xtera 7KHz Coils T305 / T505 / T705
* Coiltek 15in DD 7.5KHz

And how about 3KHz - can we Half the Freq in the Design ?
How about 14KHz - can we Double the Freq .. ?

- While the Whites Blue Coils seem to be very hard to find ...

[zoomix]

Thank you golfnut et Koala

[Koala]

connections are here

Getting hold of the correct connector is both expensive and a PITA

If I was you I would use a cut the original connector off and change for a standard aviation connector you can get a set of 5 (10 pieces) for the price of one original slimline connector

[golfnut]

the low resistance one is tx

[zoomix]

Given the complexity and the difficulty I had for proper coil for TGSL, I'll buy a coil for IDX pro. I already have the PCB and components.

Does anyone could give me the connection diagram of the blue max 950 LOOP white's original?

Is it with my inductance meter I can identify TX and RX coils knowing that there are parallel capacitor?

Thank you to you

[golfnut]

some peopl like block diags rather than unpicking schematics,

Here is a simple block of these type of machines

[golfnut]

Yes, popular and effetive, a DD


In PP it will sound off, If the POT P4 is set too high ( Clockwise if wired correctly ) - you back off the pot to just NO Tone, then do slow mo sweeps to locate target,, precicely

for digging with a small hole,

Works best with a concentric really.


PP on idx isnt Non motion, so still need a sweep, its just a low frequency IF channel

Normall have pp off, so your in disc mode

[golfnut]

The assumption is that the RC Hold circuit is after an OpAmp amplifying each Channel.
The Diode is needed because the Voltage would usually average to Zero between Positive and Negative Wave Peaks.

"But all signals are too small to break thru the diode" You may try an opamp presision rectifier here, elliott sound products website has good one of these"

Of course, I am probably just approaching an OpAmp Integrator Circuit anyway ...

Attached is a few Integrator Examples.
[ATTACH]30316[/ATTACH]

"" attachment wont open ""

If Input Frequency is about 6.5KHz, then I would probably aim 6.5KHz in the Integrator.

"" no, after the mixer or sychronous detector, the I.F. or baseband has signals relating to sweep speed and are centred around 8Hz ""

[ampirate]

Well, via experimenting,
I find the best Shape, so far, for the D-coil is a Pair of SemiCircular Coils ...

Does this sound right ?

-

Also, What is the use of the PinPoint Button ?
- It ALWAYS Buzzes if I hold the PinPoint Button ON ...