[Milsurplus] Need settings for OA3 and OD3 tubes for my Simpson 600 tester

[Bruce Gentry]

The two tubes are totally different even if they glow beautifully. The 
0A4 is a cold cathode gas filled triode for timer and control circuits, 
and functions very much like an SCR.  The 0A3 and 0D3 are gas diodes 
that within design limits and operating parameters have a steady voltage 
drop, acting much like a Zener diode. They are used as shunt regulators 
or voltage references.   Testing the 0A4 on many testers involves 
turning a control until the tube fires and then comparing that point to 
the reference on the chart. Testing the regulators on a tester equipped 
for them usually involves watching the meter while increasing the 
voltage applied to the tube to check the firing voltage. Once this is 
found to be satisfactory, the meter is observed to see that it remains 
steady as other controls are turned to change the current flowing 
through the tube. 0A4s do become lazy and unstable with age and use, but 
regulators rarely fail, and when they do, they either won't fire at all 
or the glow starts to flicker and the voltage drop becomes erratic.

         Bruce Gentry, KA2IVY

On 3/15/16 3:19 PM, Doug Hensley wrote:
>
> My 600 tube list shows an 0A4 and under that setting some new 0A3's 
> test low but
>
> test.  I have nothing similar to the 0D3 on the chart.
>
>
> Any ideas or past notes that might assist?
>
>
> Thank you,
>
>
> Doug W5JV
>
>
>
>
>
>
>
>
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