Sovereign Coil.

[Geo]

Hi.
I want to make a 15'' coil for my Sovereign ST. Prototype Inductance is 1010uH as i measure with my inductance meter. So i need 39 turns for my 37cm Coil housing. But when i will put the foil for shielding, the inductance will change.
Knows somebody how many changes the inductance, so to calculate the coil exactly????

Regards

[bbsailor]

Hi.
I want to make a 15'' coil for my Sovereign ST. Prototype Inductance is 1010uH as i measure with my inductance meter. So i need 39 turns for my 37cm Coil housing. But when i will put the foil for shielding, the inductance will change.
Knows somebody how many changes the inductance, so to calculate the coil exactly????

Regards

Geo,

Adding the shield will make the inductance a little higher. As you wrap the coil and squeese it tighter the inductance will also go up. If you wind the coil with one less turn you will reduce the inductance by about 58uH per turn for your coil. This is based on my quick calculation but only in the range of 36 to 39 turns.

Also, as you change a round coil into an oval coil or "D" shaped coil the inductance will drop slightly. Try putting the coil in it's final shape before taking measurements. I suspect that each coil is actually about 11" (about 280mm) in diameter to fit the DD coil housing.

Try one less turn, shield the coil, take measurements and post the results.

Congratulations on winning the contest!!!

bbsailor

[WM6]

Knows somebody how many changes the inductance, so to calculate the coil exactly????

Dependent of way you produce coils (how tight is pressed, the intermediate thickness of insulation tape between shielding and windings).

My approach to construction increase basic coil inductivity about 3%.

[Geo]

Geo,

Adding the shield will make the inductance a little higher. As you wrap the coil and squeese it tighter the inductance will also go up. If you wind the coil with one less turn you will reduce the inductance by about 58uH per turn for your coil. This is based on my quick calculation but only in the range of 36 to 39 turns.

Also, as you change a round coil into an oval coil or "D" shaped coil the inductance will drop slightly. Try putting the coil in it's final shape before taking measurements. I suspect that each coil is actually about 11" (about 280mm) in diameter to fit the DD coil housing.

Try one less turn, shield the coil, take measurements and post the results.

Congratulations on winning the contest!!!

bbsailor

Hi bbsailor.
Yes the round coil has about 5...7% more inductance than the oval.
I made the Tx coil with 40 turns and it is 1250 uH. I did not fixed it so i will take some turns. If with shield the inductance is going higher then i must remove 5 turns, but i have the opinion that the shield decrease the inductance of the coil.

Regards

[Geo]

........... double publication

[Geo]

Dependent of way you produce coils (how tight is pressed, the intermediate thickness of insulation tape between shielding and windings).

My approach to construction increase basic coil inductivity about 3%.

3% at 35or 36 turns is 1 turn. So, not so big important if it is 1.65 or 4.4%... i will revove again 1 turn.

Thank you

[Geo]

Finally i removed 4 turns. Now with 36 turns coil has a Inductance of 995...1000 uH. It will take other 20...40 Uh from the shield, so it will go at 1020...1040uH. It is OK for the 1010 that has the original coil.
I used 0.40mm wire (i had not other more thick). I read somewhere that for the Tx power of Sovereign it is good to use 0.45mm wire, but i think that the difference will not be so big. Now i want to make the shield.
I made a lot of coils with foil for shield, but never with graphite??? It is difficult to find graphite at the shop of my City. I think that the spray graphite that we used before years at the display of CRT TVs is good and maybe to find it.
What are you think????

Regards

[WM6]

Finally i removed 4 turns. Now with 36 turns coil has a Inductance of 995...1000 uH. It will take other 20...40 Uh from the shield, so it will go at 1020...1040uH. It is OK for the 1010 that has the original coil.
I used 0.40mm wire (i had not other more thick). I read somewhere that for the Tx power of Sovereign it is good to use 0.45mm wire, but i think that the difference will not be so big. Now i want to make the shield.
I made a lot of coils with foil for shield, but never with graphite??? It is difficult to find graphite at the shop of my City. I think that the spray graphite that we used before years at the display of CRT TVs is good and maybe to find it.
What are you think????

Regards

Nice work, Geo. Instead of graphite you can try shielding with insulated stainless steel wire (as for garden use) tihten spiral winded over coil winding.
Not easy to make but maybe the best shielding in my use.
For solder stailess steel wire on copper wire, use (acid) solder paste and a powerful soldering iron.

[Geo]

Hi WM6

Another good way is to open a MK capacitor. With every capacitor i can shield about 15cm coil, so with 6..7 capacitors i have ready the Tx coil. The MK capacitor inside has a foil (very thin) that from the one side is insulated and from the other is sprayed with graphite. Very good results but it need more more time, and i am a little lazy.

Regards

[WM6]

Very good results but it need more more time, and i am a little lazy.

Yes, good idea.

Lazy? Imagine that Olympus is full of gold, and maybe helped.

[Geo]

Yes, good idea.

Lazy? Imagine that Olympus is full of gold, and maybe helped.

Hahaha.. other thing the gold, other the laziness.

But if you want gold, you are welcome to Olympus

[Geo]

I did not found graphite spray at my City . So i will look for at another City or at ebay. Does somebody knows one good type of graphite spray so to order it???

Regards

[WM6]

I did not found graphite spray at my City . So i will look for at another City or at ebay. Does somebody knows one good type of graphite spray so to order it???

Regards

Very good graphite spray (conductive) is Graphit-33 from Kontakt Chemie.

I am sure that can be found in your country too:

http://www.europe-audio.com/Product.asp?Product_ID=3308

[Geo]

Very good graphite spray (conductive) is Graphit-33 from Kontakt Chemie.

I am sure that can be found in your country too:

http://www.europe-audio.com/Product.asp?Product_ID=3308

Hi.
I ordered it. I believe next week to have it.
Today i had not how to spend my time and i opened the original coil (Tornado 1000). Maybe tomorrow to post some photos because it is a interesting coil for it construction method.
I revoved the amplifier but i lost one SMD resistor so i don't know what it is. Amplifier use the AD797, so if somebody has this schematic, please post it here....i want to check the amplifier and to put it in the new coil.

Regards

[bbsailor]

Geo,

Here is the Sovereign preamp schematic.

bbsailor