[Elecraft] (OT) smoke test

[williamsonr at pbtcomm.net]

I too have had one of these "let go".  I have a lamp near my reading chair that used a 3 way Fluorescent lamp.  While reading one day I began to hear a hissing sound followed by a loud bang (like a fire cracker) and "lights out".  Upon examination the class envelope of the tube near the base had overheated to the point of flowing and eventually bursting.  Not a great feeling - and again if I had not been home at the time to pull the plug????? Do these things have a safety issue?

Rodger, N4NRW

---- Original message ----
>Date: Sat, 04 Oct 2008 20:39:55 -0800
>From: Jim Wiley <jwiley at alaska.net>  
>Subject: Re: [Elecraft] smoke test  
>To: w1tf at yahoo.com
>Cc: Elecraft at mailman.qth.net
>
>Ralph -
>
>
>Many - not all - fluorescent  lamps (I am assuming you are  talking a 
>CFL , or Compact Fluorescent Lamp) have a small  resistor used as a fuse 
>for the ballast.  The ballast is in the base which supports the 
>discharge tube (the fluorescent portion).  The ballast develops the 
>voltages needed to initially fire the tube (when cold)  and limit the 
>current once the arc is initiated.  It consists of several capacitors 
>and resistors as well as a few semiconductors.  As the tube ages, the 
>current draw increases.  At some point, it becomes too much, and the 
>ballast fails.   To prevent a really catastrophic failure, a small 
>resistor (typically a 1/8 or 1/4 watt unit) is used as a fuse.  Overload 
>destroys the resistor, cutting off the current.   Why a resistor?   They 
>are much less expensive than fuses, particularly at low current 
>ratings!  The light from a CFL comes from a mercury-vapor arc inside the 
>tube, which emits large amounts of ultraviolet light.  The phosphor on 
>the inside of the tube converts the ultraviolet energy into visible light.
>
>
>- Jim, KL7CC
>
>
>
>Ralph Tyrrell wrote:
>> As I sit at my computer the radio desk is to my back. I heard a burst of static behind me. That was odd since no radios were on.  The only thing on at the radio desk was the desk lamp and a power supply that keeps the batteries charged. Both are plugged into a strip that switches power to them.
>>
>> I went over to the radio desk and looked at my equipment, both off. Still puzzled I turned on the 2m rig, all normal. Then I turned on the K3. All normal. I turned them off again. The K1 sits by, not connected to anything at this time.
>>
>> Still puzzled  I sat there wondering if something had happened to my battery bank or one of the batteries.  I have three 26AH batteries in parallel. Each battery is fused before to goes to a fused buss.
>>
>> Then my nose began to notice the smell we all dread. Something electrical was over heated.  Still I did not noticed a symptom I should have noticed earlier, the desk lamp was off. I touched the top of the lamp and it was very hot.  The bulb, a 13 Watt Florissant had failed. The ceramic base was too hot to touch. 
>>
>> How often do Florissant bulbs fail this way?
>>
>> I had the feeling that if I were not there a fire may have started.
>>
>> 73, Ty, W1TF, K3 #696, K1 #1423
>>
>>
>>
>>       
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