[Heathkit] HW-16 question

[Bill Cromwell]

Hi Lynn,

While waiting to hear from somebody who can answer your question about 
why, I might suggest installing the replacement and trying it out. Then 
reversing the leads and trying it again. See if there is a discernable 
difference. The neon bulbs are not polarized in the way that diodes or 
electrolytic caps are and nothing catastrophic should happen. Some neon 
bulbs have the needed series resistor (current limit) built-in and the 
dot may indicate which lead is connected to that resistor.

One of the key characteristics of the neon bulbs (and other gaseous 
tubes) is their striking voltages and operating voltages. Maybe somebody 
else can confirm what part number should replace the broken one.

I have an HW-16 that I got as a basket case and has been waiting for my 
attention, I am getting more motivated to move it into my bench and 
start down the same road you are on. Good luck to you with yours:)

73,

Bill  KU8H

On 8/22/19 10:49 PM, lynn simons via Heathkit wrote:
> Hey Guys,
>     I am in the process of restoring an HW-16 and found the neon bulb that is used in the sidetone circuit was broken. The schematic just lists this as a "neon bulb" as does the parts list. In the assembly instructions it mentions the bulb has a red dot on one side and it should be installed on the circuit board with the red dot on the side depicted on the silk screening of the circuit board. The sidetone circuit is a relaxation oscillator and my understanding is that I can just replace this bulb with another neon bulb like a NE-52 or such. Is this correct? Also, I didn't know that neon bulbs could be polarized such that they had to be installed in a certain orientation. Can someone elaborate on this for me?
> Thanks,
> 73, Lynn,  KJ3V
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