pi dd coil

[Anonymous]

hello there, good to see some helpfull people about.
please forgive me but as a newb i have a few q.
1)are there any programs for coil calculations?
2)are there plans for coil constructions?
3) what about dd coil plans?
thanks for your time.
appriciate reply.
greetings from down under. peter

 

[Anonymous]

Hi Peter,
Below is a link to one of the better coil calculator programs I have found. I find if I use .2 to .25 inch (5mm to 6mm) for the coil length and then use the read the .1% accurate calculation, the numbers closely match the readings I obtain on a LCR meter.
As for winding the coil, I just try to be reasonably neat and either use stranded or Litz wire. However, basic PI's seem to work ok just using magnet wire also. At least I never had any real problem using it on some of the kits I built.
Remember to shield the coil and have a space between the coil windings and the shield. Eric has mentioned in the past he wraps the windings with spirawrap and then uses a very thin lead tape for the shielding. This seems to work quite well. However, finding thin lead foil tape is a problem. Others use different types of conductive paint. I have even used semiconducting tape. However, I have noticed a slight increase in the noise level using this tape. I suspect I will have to increase the overlap to reduce the noise level. I suspect the use of a graphite based conductive paint will have about the same effect as the conductive tape.
I still haven't built a DD coil so I can't help you there.
Reg

 

[Anonymous]

thanks for that reg, will be very helpfull.
regards from down under.
peter.