I found John’s description while looking for something else!
"I use a link dipole for 80 thru 20 on a 5m mast with 1m ends. There are break points in each leg for 40m. These are 9.77m from the centre. This is where I insert the loading coils.
Everything is home brewed and the coils weigh 39 grams each and are quite small as follows:
Coil former; 20mm dia x 74mm lg PVC tubing with modified ‘Monoject’ 5ml hypodermic syringe inside. 113 turns of 0.4mm dia enamelled copper wire, close wound over 51mm length of former.
Crush 3/4 of a ferrite toroid into powder, using a hammer. Mix powder with araldite and apply along abraded piston shaft. Paint white so that calibration marks can be added later. Fix on some terminals and fit to dipole. Adjust slug for desired freq. Covers 1.7 to 2.0 MHz, though bandwidth is narrow.
(Ferrite toroid is of unknown specification, 22.2mm dia x 13.3 inner dia x 6.3mm thick. Material is attracted by a magnet. They were just lying about in the garage.)
I wouldn’t say the design is eminently reproducible or even very efficient; just a good starting point for expt and light enough to be summitted easily."
The above dates back to March 2012, which explains my imperfect memory in the previous post. Tempus frangit!