Tom's points are very interesting: I've always been accustomed to switches where
you actually design them yourself on the templates provided by the manufacturer,
so you can decide on make before break, as well as (in some types), fancy
features such as insulated back contacts, short clips, dummy clips, etc. Non US
readers note that the US terminology doesn't necessarily apply elsewhere, BTW.
Of course, for home brew, it's a matter of what you can get.
Using a 'progressively shorting' switch may not always be necessary: a straight
forward 'break before make' wired to short out all the unused portion of coil,
rather than all the taps on the coil, can work just as well. 'Progressively
shorting' switches are of course limited in the number of positions available.
One problem with rollers is if you need to short just a few turns at the end:
they can then get very hot. I built one of the 'ultimate transmatch designs';
that had the problem on 160 of the last two turns overheating. Rewired so as not
to short the unused portion, the strays and the unused L resonated at 14 MHz and
arced over to chassis!
Note Murphy working overtime........
Those switches from Fair Radio are a good bargain, although possibly marginal at
1500 watts. Cheap enough to keep a spare or two for if they do
flash......although as the contacts are just hard copper sheet (as opposed to
annealed), attached with 6-32 brass hardware, they're easily replaceable.
73
Peter G3RZP
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