Raith: please don't use 15-20.9KV or 23-30KV

[Mark Topinka]

(in other words, 0-15KV is ok and 21-23KV are probably ok, but DO NOT set 
it to 15-20.9KV or 23-30KV : these ranges cause intermittent EHT trips, 
which can occasionally turn into the more serious and dreading "arc", which 
can ultimately seriously damage the instrument)   Sylvia had problems with 
repeated EHT trips (even after a LONG pumpdown) today and we do not want a 
repeat of what happened earlier this year (right!?) until we sort out what 
exactly is going on.  -Mark