The G800/1000/2800 manual shows the lamp to be 12V/100mA, and running on a
12VDC regulated source that is not current-limited. As we know, a lamp's
filament has a very low cold resistance, and inrush current typically exceeds
5X the running current. High inrush current causes mechanical shock to the
filament and early failure. A resistor will limit the inrush current but also
limit the running current. You need a "brick wall" current regulator. The
ubiquitous and inexpensive LM317 can easily be configured to do that with one
resistor. I did that many years ago with the GOW dial lamps in my olde Kenwood
rig, and the lamps are still FB. Hint: the '317 will drop 1.2V so, use a lamp
rated a bit lower than the supply voltage if you want full brightness. RS
stocks the 317T for $2.69 but they can be found for pennies elsewhere (Mouser
#863-LM317TG = $0.51).
Single LEDs have a narrower dispersion angle and typically give you that
"lovely" spotlight effect. Some LED lamp assemblies get around that by using
multiple LEDs arranged in different positions. Another technique is to choose
a wide-angle LED and/or scuff the lens so the spotlight effect isn't quite so
bad.
vy 73,
Bryan WA7PRC
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