I never knew glow starters were this bad until today! I've just acquired a GE F18/35 which is completely mercury starved, it's turned out to be more useful than I first thought. Because so little light is produced from the discharge you can see the damage done when the cathodes aren't sufficiently preheated! Almost every time on a standard ballast
and starter switch. Upon switch-on, the starter closes and preheats the tube's cathode filaments. Upon opening, the magnetic field within the ballast
collapses, causing a voltage pulse which strikes the tube. This is often repeated twice or more, causing the distinctive blinking at startup.">switchstart circuit with a 115/500 starter the cathodes flash bright blue when the starter opens, even on a successful start!
This is good clear evidence of the emitter being sputtered off the cathodes much like you see after the ignition of a brand new SOX
I've found that by using 115/200 starters the damage is significantly reduced, probably only about a third of time the arc strikes with cold cathodes. Next thing to try was a Pulsestarter, as I suspected the arc struck without appearing to do any damage to cathodes, not the slightest evidence of sputtering at all!
Ideally I need a clear tube to get a proper look at what's going on and I need to test it on the 3 common types of gear (SS
, SRS and QS
). This has put me right off glow starters now though!