OK - I'll try that out on some off-cuts, assuming that such
things are available.

Otherwise - I'm collecting various bits of metal to make up a
bug key but am distracted by vertical antenna and its ATU.

I am trying to conceive of a minimal switching scheme to accommodate
the 10 ATU configurations discovered so far....
Straight through
Series C
Series L
Series C-L
"L" network with C on TX side
"L" network with C on ant side
"PI" network
"T" network
Parallel tank, series fed
Parallel tank, parallel fed

"john jardine" wrote in message
...
"Airy R. Bean" wrote in message
...
Assuming that one could obtain a slab of marble for the
base of a home grown bug key, is it an easy thing to
polish and to drill?
Does one use ordinary masonry drills?
Any undertakers out there?
An ordinary masonry drill is perfect.It goes through it like cheese. The
material is basically quite soft and can be easily shaped with an angle
grinder and a cheap diamond cutting disc (those for cutting bricks, flags
etc) . For final levelling use various grades of car 'wet-n-dry'
(Silicon
Carbide paper) and finish using Silicon Carbide (or even diamond!)
'lapping
paste' slurries.
(nb. for rust stains soak in oxalic acid)
regards
john