Assuming that core is mostly air... this would be ~ 18 uH

rob34 wrote:
rob34 wrote:

I have a big roller inductor made by E.F.Johnson model 226-5. It would
make a great coil for the homebrew linear as it could easily take 5kw
and has enough inductance for 10 through 80 meters. It is a beautiful
silver plated coil in excellant shape that measures 13.5 inches from
one end of the shaft to the other and the coil is 3.5 inches in
diameter. It measures 8.5 inches from end to end of the insulated
plates which holds the coil itself. Very heavy duty construction, just
a little too big for my needs. You can go to this website to see
pictures on it: http://photos.yahoo.com/rob34115 and look at Rob`s
photos. There are three pictures of it and some electrolytic caps and
parts for a HV power supply I am selling. Please make me a reasonable
offer on these items! WB8VWI Rob

As can be seen from the pictures there is 14 turns at 3.5 inches in
diameter which is more than enough inductance for 10-80 meters. I am not
sure what the actual inductance is, you might be able to go to a website
with the model number and get the exact specs. WB8VWI Rob