/diy/ - Do It Yourself

First time posting here. This thread seemed like the appropriate place to ask about this. If not, let me know and I'll start a new thread.

I was planning on building this using materials I have on hand. I have 24 and 26 gauge enameled wire, and several different diameters of PVC. (Also have the remaining parts.)

The author didn't note the inductance values of L1 and L2. To make matters a bit worse, the author notes the PVC actual diameter is 3.25", but the one I have is 3.5"

Using the formula below:
L= (a*a*N*N) / [(18*a)+(40*l)]
where
L= Inductance in microHenries
a= Coil diameter in inches (PVC diameter plus wire diameter)
N= Number of turns
l= Overall length of the coil in inches

Using 22 gauge wire (.0267") and assuming he did use 3.25" diameter PVC, I calculate L1 as 203uH and L2 as 143uH.

Not sure how to determine inductance value at the center taps. Also, I'm not sure what formula defines the space between L1 and L2.

My goal is to use 3.5" PVC and 24 gauge (0.0213") or 26 gauge (0.017") wire. Any input would be appreciated....