I have now done a couple of exhibitions using the Alex Jackson couplings and have made a few tweaks. Initial problems I found were that they didn’t seem to drop well when over the magnet. On investigation I found that the droppers were too short and the magnets were not strong enough. I have now found that a 5mm length dropper is optimal. To this end I have made a small jig to make them . This consists of a 5mm brass tube, large enough to take the wire for the dropper, soldered to a piece of scrap brass. A small bend is made in the wire and flattened in a vice. The wire is then inserted into the tub and cut to length. The magnets work much better having changed to DC current.
The second problem was that when pulling a long train the couplings would lock because the wire being fine led to the bend to form the nose of the coupling opening out and locking. On the advice of Iain Rice I have now soldered all the noses and this has solved the problem.
I had persevered with the B&B couplings on my Broad Gauge stock, but despite trying all the tricks that various people have suggested they still become uncoupled at the wrong time and are inconsistent in coupling and uncoupling when shunting. I have now given up and have fitted AJ couplings to all the freight stock. In this case I have fitted the couplings the traditional way, ie pulling from the opposite end of the wagon. The coupling height bar now has a notch bent in it in order to centralise the coupling. The position of the notch is set using the coupling height gauge.
I feel I am now hooked [sorry for the pun!] on Alex Jackson couplings. They are unobtrusive, work well as delayed uncouplers and stay coupled when they should do. I find that being careful with handling the stock and storing it properly means that I do not have to spend loads of time at exhibitions checking the heights etc of the couplings, which is a criticism that some people have made of the design.