Surf PI DD coil

[plumabob]

I have tried many coils on the Silverdog SPI, but this 13 x 11 seems my best so far. It may be slightly less deep the the same sized mono but not by much, tough to even measure the difference. It is much quietier and because of that alone I'm thinking it will pull in more targets. I'm planning a trip down to the beach soon and I will update.

Bob

[bernte_one]

hello bob

more infos please

have tested an old co planar coil which i had here works great also, you can double the target signals

but a dd coil i dont have tested

[homefire]

Yep! More Info PLEASE?

[plumabob]

For now I can give you the coil specs if that is what you are asking. I believe the wire was stranded 22awg teflon tinned copper. I don't count turns so I can't help u there, sorry.

TX is .291uH 1.34R
RX is .452uH 1.89R
Shield is conductive rubber shielding tape.

I can sample at the lowest delay settings on the SPI. I can hit a nickel at 13-14 inches in air testing. A tuna can close to 30 inches.

Hope this helps out.

[bernte_one]

hello bob

and how did you connect tx and rx to surf pi board

[mehdi]

more info please!

[plumabob]

Now I can answer that I have a specific question. The connection is very simple. You must break the contact in between R6 and R7. Unsolder the end of R6 and solder the TX to that end of R6. The RX will go to the terminal marked coil. You must use a dual coax cable to your coil. I'm using Mogami 2552 which seems to work very well.

[bernte_one]

thx bob,

that are facts i can work with

[Vortxrex]

I was playing around with my surf PI the other night. I wound two 10 turn coils & set them in a DD or OO config. I was getting about 12" on a nickel with is consistent with what I am seeing on a monocoil. The coils are connected in series.

Looking forward to hearing how Bobs "Beach" test goes. I had mine out on the Oregon Coast last week (with a monocoil) and had lots of noise problems.

Dave Frank

[plumabob]

DD beach testing went well. In the wet sand coil was very quiet with just an occasionally blip if a wave washed by. Once submerged in the water she stayed quiet. I wish there were more targets around but I'm satisfied with the performance. Scratchy targets were usually small bits of iron. Solid hits were coins or some surface bobby pins. I had the delay right at 11u-12us which is as low as I could drop it. Ran slightly smoother a touch higher but was perfectly usable at my lowest settings.

[golfnut]

ALL, I may attempt a triple.

2 Tx's with Rx imbetween.

O0O type.


I was going to feed the same Tx pulse to both Tx fets.

Rx in the centre.

Im going to angle the 2 Tx coils so their fields converge about 12" beneath central Rx coil.

Maybe done before but Id like to try it.

Steve

[Dx-Digger]

Do you think I would be able to use a Whites Eclipse Deep scan DD1400
its apparently 3.0 Ohms on tx coil and 38.6 ohms on rx? I only ask as I have a spare one and would like to put it to good use.
Cheers Mark.

[DIVER]

yes

[Dx-Digger]

Verification of connections for whites 1400DD deepscan

yes

Ok so I connect the one end of the txcoil to R6 and one end of the RX coil to R7,
do the other two free ends just connect to gnd?
Just need some verification please.
thanks