Many thanks to Joe W4TV and Mike W4EF for their most helpful replies.
I managed to find about 14uF worth of non-polarised capacitors, so cobbled them
all together and connected them across the CW and CCW leads. (I should point
out that we are having unseasonably warm-ish weather at the moment so my tests
are inconclusive!) The antenna rotates, but the phase difference is now about
120 degrees instead of 90. I think that implies that the original capacitor is
still operational, but of course there are number of ways in which a capacitor
can fail. If that failure is resistive leakage then the extra capacitance might
not help. I am quite confident we will get some horribly cold weather quite
soon and I can then repeat the test.
I did already have a copy of the instructions for the units, but not the
marketing brochure which does contain some useful information. The schematics
in the instructions are all wrong, certainly when compared to my unit: My
transformer has two secondary windings - the tapped one for the motor drive and
a separate one for the control/indication. Also, the transformer is clearly
marked as 28V. I did purchase the equipment a long time ago when I was G3RBP so
it is 240V 50Hz but I can't see that would make any difference except for a
small phase change.
Anyway, thanks again for the help.
73 Roger
VE3ZI
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