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Author Topic: Drake L4B Pilot Lamps Voltage?  (Read 1150 times)
DK8NX
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Posts: 4




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« on: April 05, 2009, 08:53:47 AM »

Hi, using a Drake L4B:
do someone know the voltage of the pilotlamps, used for the plate and grid meters
thanks,73
Wolfram
DK8NX
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W1QJ
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« Reply #1 on: April 05, 2009, 03:10:41 PM »

The lamps themselves appear to be simple neon bulbs which are fired by the 120vac with about a 100K resitor in series with the neon bulb.  If your bulbs do not light, it could be a bad resistor or a blown neon bulb.  It seems that the resistor might be inside the bulb housing.
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VR2AX
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Posts: 577




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« Reply #2 on: April 05, 2009, 05:53:00 PM »

Wolfram/Lou,

I believe the meter lamps they are 5V AC bulbs, which take their power of the 5V filament supply to the 3-500 tubes. Lou is possibly thinking of the 120V neon lamps related to the on/off and ssb/cw switches.

I have the bulb model number ..somewhere...from memory, they are Chicago Minature bayonet incandescent types. Mouser sell (or used to sell) them. Bulbs are clear glass, if you paint them with blue acrylic paint, the illumination on the meters will be less.

I will try to dig out the information on the bulb number, but it should be on the schematic (just check the Mouser catalog).

73,
Wyn, VR2AX
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VR2AX
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« Reply #3 on: April 05, 2009, 06:13:19 PM »

The meter bulb is a Chicago Minature #1850 (or CM1850).

Mouser part # is 606-CM1850.
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W1QJ
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« Reply #4 on: April 05, 2009, 08:22:28 PM »

Indeed, I was thinking of the on off bulbs.  I forgot which bulb I was looking fore on the schematic.  The meter bulbls are off the filament voltage like the Sb-220's.  The bulb number should be a typical #47 bayonet type.  Thanks for the correction Wyn.
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DK8NX
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« Reply #5 on: April 06, 2009, 01:47:31 PM »

Many thanks dear friends, very helpfully, found a dealer in germany
73 from Ochsenfurt
Wolfram
DK8NX
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KL0S
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Posts: 132




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« Reply #6 on: April 07, 2009, 04:59:32 AM »

The meter lamps in the L-4B are GE 1850:

Miniature Lamp Voltage Rating 5 Volts Trade Lamp Number 1850 Power Rating 0.09A Lamp Description Signal Plane of Filament Perpendicular Candle Power 0.25 Candela Rated Average Life 1500 Hours Base Miniature Bayonet Bulb T-3 1/4 Maximum Overall Length 1.19 Inches

As I recall the #47 is not a direct replacement.

Dino KL0S
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