Sorry, Andy, I have no idea where the figures for the coils are now; most likely in the cardboard around someone's Christmas present
The former is 40mm plastic waste pipe. The wire is enamelled copper close wound; I think 26swg. There is an unknown number of whole turns occupying 16.0mm. (Protected by layers of tape.) The number 29.4 is written on the pipe; inductance in micro-Henries? (I know it took me a long time to get this correct and the two coils equal. The calculations (from some formula found on the Web) gave quite unsuitable numbers of turns; the end result is based on actual measurement in the garden and experience in the field suggests that a little more inductance would be handy as Allan pointed out on Tuesday that the band is noisy above 3.6MHz which is about where the coils give the best SWR. 3.77MHz was the optimum on Tuesday but this evidently varies with the terrain.
Maybe that will give you a decent start.
Edit - I made four coils; all are OK but the first two have joins in the wire and holes scattered over the pipe so the two Mk 2 version were made.