[Test-Equipment] nixies and hp counters

[Eugene Hertz]

Anyone out there in test-equipment land have the maint/service manual? Serial number is 716-14027

thanks

>-----Original Message-----
>From: J. Forster [mailto:jfor at quik.com]
>Sent: Thursday, August 25, 2005 02:22 PM
>To: 'Eugene Hertz'
>Cc: test-equipment at mailman.qth.net
>Subject: Re: [Test-Equipment] nixies and hp counters
>
>Eugene Hertz wrote: 
> 
>> Hello all, 
>> 
>> I have an HP 5245L nixie counter with a 5253A plug in that will let it go to 500mhz. 
>> 
>> I think I have two problems. First, one of the nixie displays has a strange behavior where certain numerals (not all) will sort of "half display" like the number 4 might have some of its legs glow. But oftern after 5+ seconds the rest of it will glow as it should have originally. Seems that some numerals slowly "reveal" themselves after several seconds. Other times the numeral does not display. 
>> 
>> Could this be a nixie tube problem or perhaps a driver problem? (or whatever discrete components make the nixie work?) I am really hoping it could be a faulty cap or something simple. 
> 
>It's most likely a Nixie problem. Nixies contain a small amount of radioactive material, either as a gas or a solid to 'pre ionize' the gas. Over time some of the radioactivity goes away. Some tubes may also have Helium, but I don't really know. That's why some Waber strips and switches with pilot lights flicker or fail. AFAIK, there is no cure. You can test this by shining a strong light on the 
>thing. Often they will work after being illuminated. I have an HP Numeric Display and an ESI RLC meter that has that problem. The display on the RLC meter is dark until you remove the red filter... then it works. LoL. 
> 
>> Any one on any piece of nixie equipment ever see a numeral slowly display itself? 
> 
>Yes. Could be a leaky driver, but the tube more likely. Try swapping it into another position. You might be able to trim the HV a bit to solve the problem also. 
> 
>FWIW, 
>-John 
> 
>