[AMRadio] 20V3 bulbs


Donald Chester k4kyv at hotmail.com
Sun Jan 16 15:22:46 EST 2005



>
>My Collins 20V-3 has those dropping resistors as well.  Seems like the
>"experts" blew this one.
>
>Oh, well, not everyone can be perfect.
>

Actually, the 120 volt bulbs with dropping resistors should last longer.  
The series resistance will buffer the inrush current.  The cold filament of 
an incandescent lamp has but a fraction of the resistance of a hot filament. 
  The series resistor will limit the current until the filament heats up.

The Gates BC1-T also uses those bulbs.  Right now mine are running off the 
DC control voltage I modified into  the rig.  I'm going to have to change 
the circuitry, because the bulbs have a very short life when they run off 
DC.  I forget what it is called, but there is a physical effect that causes 
incandescent filaments tot to last long on DC, even though the effective 
voltage is the same as their rated a.c.  voltasge.

Don K4KYV





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