On Sep 21, 10:25 pm, Clayton wrote:
Hi,
I have a coil that is wound on a 1.125 inch diameter form and 3 inches
long space wound with 25 turns of 11 gauge aluminum wire...
I am trying to duplicate this coil only instead of using 11 gauge wire
I am using 12 gauge aluminum wire.
I was wondering if somebody could help me out and make sure my math is
right since I am unsure of how to go about making sure I match the
inductance.

I had this figured out once but mistakenly had the wrong wire
gauges...

Any help is greatly appreciated
Thank You

Back not so long ago when you posted a similar question on the antenna
newsgroup, Owen Duffy so kindly posted a url for an inductance
calculator, which I repeat here for your benefit:
http://hamwaves.com/antennas/inductance.html. It will do all the math
for you. Well, almost all. You still need to put your dimensions in
terms of millimeters, and make sure you enter the diameter of the coil
as the form diameter plus the wire diameter, so that it's the mean
coil diameter you enter.

Cheers,
Tom

I would just visually duplicate what the original looks like. It should
be fairly close and you can spread or squeeze the turns to "tune" it to
the inductance required.

Scott
N0EDV

K7ITM wrote:

On Sep 21, 10:25 pm, Clayton wrote:

Hi,
I have a coil that is wound on a 1.125 inch diameter form and 3 inches
long space wound with 25 turns of 11 gauge aluminum wire...
I am trying to duplicate this coil only instead of using 11 gauge wire
I am using 12 gauge aluminum wire.
I was wondering if somebody could help me out and make sure my math is
right since I am unsure of how to go about making sure I match the
inductance.

I had this figured out once but mistakenly had the wrong wire
gauges...

Any help is greatly appreciated
Thank You


Back not so long ago when you posted a similar question on the antenna
newsgroup, Owen Duffy so kindly posted a url for an inductance
calculator, which I repeat here for your benefit:
http://hamwaves.com/antennas/inductance.html. It will do all the math
for you. Well, almost all. You still need to put your dimensions in
terms of millimeters, and make sure you enter the diameter of the coil
as the form diameter plus the wire diameter, so that it's the mean
coil diameter you enter.

Cheers,
Tom


--
Scott
http://corbenflyer.tripod.com/
Gotta Fly or Gonna Die
Building RV-4 (Super Slow Build Version)

Thanks Tom,
That calculator doesn't work for me for some reason. Every time I
tried to use it,it comes up with an error.
I have tried several different calculators but get varying answerers.

Hi Scott,
If My math is right I would need 23.5 turns of 12 gauge wire to reach
the same inductance as the original coil.

Sorry for what may seem like a repeat post,but for some reason I can
not seem to get comfortable with coils and inductance.

Thank You

On Sep 22, 9:47 am, Clayton wrote:
Thanks Tom,
That calculator doesn't work for me for some reason. Every time I
tried to use it,it comes up with an error.
I have tried several different calculators but get varying answerers.

Hi Scott,
If My math is right I would need 23.5 turns of 12 gauge wire to reach
the same inductance as the original coil.

Sorry for what may seem like a repeat post,but for some reason I can
not seem to get comfortable with coils and inductance.

Thank You

I just ran the calculator at the referenced web site. It suggests
that you will have a hard time telling the difference between 25 turns
of 11AWG and 25 turns of 12AWG, wound on the same form and to the same
net length. The calc for the 12AWG shows inductance about 0.3% higher
than for the 11AWG. I'd have guessed it would be slightly lower. The
SRF's and Q's are similarly close, by that calc.

My feeling is that you are worrying the problem to death...

Cheers,
Tom