Quote:
Originally Posted by David G4EBT
I always warm up the tubes for five minutes before I use the box. No idea whether the need to do that is just an 'urban myth' or whether it does make a difference
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I've always warmed my lightbox tubes too (although for 15 mins) and did find that if they weren't warmed, the exposure results were variable at times.
One place I worked at had theirs permanently on during the day (it had shutters that opened and closed to admit the light to the pcb material).
Terry