[volt-nuts] Neon bulbs for HP 3420B or 419A chopper circuit

[Charles Steinmetz]

David wrote:

>> to buy NEW bulbs from a reputable manufacturer who provides specs
>
> Any recommendations - I can't find a source in UK.   I know Philips used to make them, but where I'd buy a few &deity only knows.

Google is your friend.  neon, bulb, lamp, radioactive, and "dark effect" 
are good search terms.  Here's what I found in about 5 minutes (all 
US-centric):

Mouser and Digi-Key both have quite a variety of neon bulbs available, 
including bulbs with wire leads from VCC, JKL, and Lumex.  You would 
need to review datasheets and contact the manufacturers to inquire about 
radioactive additives:
<https://www.mouser.com/Optoelectronics/Lamps-Holders/Lamps/_/N-5g6r?Keyword=neon&FS=True>\

Other large distributors probably have similar selections.

This catalog from  VCClite indicates that some of their bulbs have 
reduced dark effect, including the A1D-T and A2B, both of which Mouser 
and Digi-Key carry:
<https://vcclite.com/wp-content/uploads/wpallimport/files/files/NeonIndicatorLamps.pdf>

You will probably still want to find out for sure if the dark effect 
reduction is due to a radioactive additive.

Here's some general information on glow lamps:

25 pages of glow lamp specifications from GE back in the day.  Quite a 
few of them are listed as having a "mild radioactive additive" to reduce 
the dark effect:
<https://static1.squarespace.com/static/57ae25c75016e1690c41b053/t/57ae2fd003596ed24fa8f54c/1471033297306/Glow+Lamp+Specifications.pdf>

The 1966 edition of the GE glow lamp manual can be found here:
<http://www.ko4bb.com/getsimple/index.php?id=download&file=06_Misc_Test_Equipment/GE/General_Electric_Glow_Lamp_Datasheet_1966.pdf>

Best regards,

Charles