Screening experiment

[satdaveuk]

Hi had very good results using Tesro spec coil inductance 5.7/6.2mh, black wire n/p shield return for RX/TX, coil socket on MD bonded to earth.
Trying this method too reduce chatter on ground tests using silver dogs mod for more depth.
Using shield braid from a good quality TV coaxl cable wound directly onto coil windings.

Will let you all know results soon, Watch this thread

Regards

[bernte_one]

attention material could be to thick

[satdaveuk]

attention material could be to thick

Yes it could well be bernte, infact in theory it is, but worth the experiment in real use dont you think?, so many theorys over the years have been proved wrong in practice.

Regards

[bernte_one]

thats exactly what i think
experience is the best teacher

i tried thick adhesive tape instead of thin mylar foil on my tgsl coil and a good tuned piece was crap i wasnt able to scratch the foil off it was easier to wind a new one

i only wrote because i had made it wrong but maybe your material is better

[satdaveuk]

I also tryed aloy tape and that was crap, best ive used so far is mylar, just trying for that extra mile.
The braid im using is just wound on tight with twin stick each end so will be a 30secs job to remove and the cables im using is from lenths left off from drums in the workshop, so theres know money outlay at all just a bit of time.

Regards

[Max]

I also tryed aloy tape and that was crap, best ive used so far is mylar, just trying for that extra mile.
The braid im using is just wound on tight with twin stick each end so will be a 30secs job to remove and the cables im using is from lenths left off from drums in the workshop, so theres know money outlay at all just a bit of time.

Regards

It works, I've used in at least 5-6 coils for VLF and a couple for PI; the braid solution is good as could be good using layers od litz wire over coils, it's also really cheap compared to mylar solution

what's important in shielding the coils is that very small currents may develop in the shield and there is a gap, somewhere, and not closed loops (unless conductivity is very low like with graphite)

if use copped tiny wires braid (like from coaxial cables for TV or radio stuff) gain good results this way, sometimes using silvery braids things get worse this way depending on wires material

it's a cheap alternative to using aluminium foil e.g. for kitchen purposes, that's thick and much respect to mylar layer

mylar is the best cause shields from EMI and gives enough conductivity to create a ground plane under the coil but is not cheap and not easy to apply most o the times

another alternative is using graphite, graphite based putty (like aquadag varnish), nickel spray or other conductive paints (e.g. based on copper or silver), and for PI the best is lead tape very thin (used in some satellites and military US things... expecially of 60-70s)

[Qiaozhi]

... and for PI the best is lead tape very thin (used in some satellites and military US things... expecially of 60-70s)

Eric Foster once told me that he uses lead tape in his PI detector coils.

[Max]

Eric Foster once told me that he uses lead tape in his PI detector coils.

Hi
yes, it's cause of signal decay time for lead, the lead tape could be substituted with other metallic tapes but lead is soft and easy to get so thin in rolls. In military applications I know it was employed both in satellites (in early ones) and missiles and other things... usually its purpose was to wrap wires for shielding purposes to reduce crosstalks and add interference and radiation shields to delicate signal path or instrumentation

of course in this use of lead tape has been exceeded by new materials and radiation-resistant or radiation-hardened semiconductors so today use is mostly for golf clubs balancing and few other "sport" applications as counterweight for tools etc.

not so easy to find, but still manifactured: today in the EU lead is illegal for too many purposes... I think

[Qiaozhi]

not so easy to find, but still manifactured: today in the EU lead is illegal for too many purposes... I think

It still seems to be on sale here in the UK.
http://www.gamolagolf.co.uk/acatalog/Lead_Tape.html
Might be worth a try.

[Alexismex]

http://www.golfsmith.com/product/300...tape-1-2-x-75-

[Max]

It still seems to be on sale here in the UK.
http://www.gamolagolf.co.uk/acatalog/Lead_Tape.html
Might be worth a try.

Hi,
yes, I think it's worth a try if one is making coils for PI detectors

there is also this one from 3M , don't remember well about required thickness for shielding but think something from 2 mils to 6 mils (say from 0.05 mm to 0.15mm) or the like could be ok

http://solutions.3m.com/wps/portal/3...beNG0PRPD79Lgl

I think anyway that the smalle the thickness the better cause of lower conductivity of the shield wrap, think in Eric Foster's coils was around 2 mils but not sure about

regards,
Max

[Skippy]

I have recently been looking at lead tape sold for golf club balancing. Finding good technical information is difficult, due to the use of golfing terminology, such as 'adding 65mm of this tape will increase swingweight by 2 points'.
However, I have found that the majority of tape for sale is 0.005 inch / 0.14mm thick. When sold as half-inch wide tape, a 2 inch / 51mm length will weigh 1 gram. This thickness tape is also available in quarter-inch /6.3mm width.
But be aware, some tape for sale is 0.015 inch / 0.38mm thick, usually the quarter-inch width type. This would be less suitable for screening, I assume.

[Max]

I have recently been looking at lead tape sold for golf club balancing. Finding good technical information is difficult, due to the use of golfing terminology, such as 'adding 65mm of this tape will increase swingweight by 2 points'.
However, I have found that the majority of tape for sale is 0.005 inch / 0.14mm thick. When sold as half-inch wide tape, a 2 inch / 51mm length will weigh 1 gram. This thickness tape is also available in quarter-inch /6.3mm width.
But be aware, some tape for sale is 0.015 inch / 0.38mm thick, usually the quarter-inch width type. This would be less suitable for screening, I assume.

Hi
thanks for the info, yes maybe 0.14mm is still good for shielding, but I think 0.38 is a way too thick for our purposes here, so it's good to know there's also this thickness on sale for golf clubs balancing

regards
Max