WHITES GMT 3 Coil specs

[hoadlies]

HI TO ALL ,,I have bought a new- whites GMT3-48khz- detector & want to build a larger DD coil .. 14''x-8''..

I have measured the Inductance & ohms readings as follows ,,,TX = .28mh ,,,3.9 ohms [this measured at end of cable[ ie] the two-widest-pins..
RX= 2.88 mh ,,,17.5 ohms..[ie]]] the 2 x narrow pins the centre-pin seems N/C..

first tried for TX .2 mm-wire but ohms way out so I have now used .34 & seems OK aprox-20 turns..

As I've no smaller than.2mm wire I will wind the RX-coil with that but ohms will out ?????around 55 turns..


MORE LATER ,But I thought some-one may like the specs


CHEERS ,,,,,,,,,,,,,,BARRY.. from-OZ

[kt315]

Barry, anything to add to those pics? what size coil you measured of? good luck

[hoadlies]

HI,, KT315.. SORRY I have not dismantled the original 10x6'' DD Coil ,I just measured the inductance & ohms!!!

I am in the proccess of winding a 13-14'' x 7'' coil & found that ''now'' [after winding a couple TX that .34 wire 20-25 turns comes out the .28 mh & very close to correct ohms resistance ..
I ''now'' [after 2x try-outs ] are using the .34mm wire for RX aprox 75 turns [I wind untill I measure the aprox mh which is 2.88mh ..

I have the coils wound but not shielded yet to be able to test on gmt 3 48khz !!!!

I with post further results later..
I see your pictured coils are not DD ,but concentric ??

CHEERS MATE,,,,,,,,,BARRY..

[homefire]

Just acquired a GMT. Anyone have any more Coil Info ? Any Info at all. Concentric or DD. I have the DD 10x6 stock coil.

[kt315]

Just acquired a GMT. Anyone have any more Coil Info ? Any Info at all. Concentric or DD. I have the DD 10x6 stock coil.

my #2 post.

[homefire]

Just checked My 6x10

Pins 1 & 2 Rx 3.002mH 17 ohms

3 & 4 Tx No Inductance Reading and 87 ohms.

Something other then wire in it.

[kt315]

Homefire, difficult thing that nobody is able to help. i wait pics of board 16 years BTW. simple schematic, simple VLF coil, simple as Classic III, there are not something radical hard to remake. but full lack of infos does case impossible.

[homefire]

Yea, I scooped up that info on the Concentric. Second Tx coil is just a bucking coil I assume is 180 Out of phase with Main Tx .That should be enough info to make a Concentric for sure but I wish I knew what was in my DD to prevent me from getting a Inductance Reading on the Tx coil. No Bucking coil in the DD that I've ever seen.

[kt315]

bucking coil in DD is too. superduper geotechers are thinking there is not just cause did not see the coils in reality.
its done like small ball of wire. in this pic 8 form.

[homefire]

Never seen that done before. Must be easier to Null . Is that on the Tx side?

[kt315]

Never seen that done before. Must be easier to Null . Is that on the Tx side?

http://www.23hq.com/metaldetectorsse.../story/1674201
too big text for me ((

[kt315]

http://www.reviewdetector.ru/index.p...ost&id=2965233
fuma writes thats RX.
http://www.reviewdetector.ru/index.p...=155140&st=280

[kt315]

[homefire]

I can say Yes and No in Russian. Don't think that's going to work for me.