B7971 - better contrast

[Robert]

Not my auction but I saw this https://www.ebay.co.uk/itm/266322565516?mkcid=16&mkevt=1&mkrid=711-127632-2357-0&ssspo=v3sg3SvYRJa&sssrc=4429486&ssuid=U1YeAcPgQ5y&var=&widget_ver=artemis&media=COPY

In the description it says “This sale is for lots of "Pin-Top" version of the B-7971. The rare "Pin-Top" versions are made with a darker background on the segments that provide better contrast.”

I have some of these but have never noticed this

Rob

[Jeff Walton]

I have a number of these "rare pin-top" B-7971's and do not find any significant difference in contrast with the Ultronics versions of the 7971s .  The pin-topped or "antenna top" construction is an early format that uses a wired backplane instead of the PCB style interconnect.  It's a nice tube that looks good as a group in any clock.  There is no practical difference in operation  or appearance and there are certainly some MOD-6 clock owners that have full sets of these tubes in operation will tell you that they are equally reliable.   They will have date codes in the mid-1960s. 

It is uncommon to see a group like this available.   $250 to $275 each per tube seems to be the going price on ebay these days.  Overpriced but worth whatever someone is willing to pay.  

My first tubes were $8/pair from Buckbee-Mears and Polypaks back in the early 1970's and included the boards with each pair.  

Jeff 

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[Robert G. Schaffrath]

I have one of the pin top tubes (https://n2jtx.com/NixieClock/Used%20Burroughs%20B-7971.jpg). Unlike most of my other tubes, it is a Burroughs branded tube and not Ultronics. The only thing I ever noticed different about it was it seemed to have a deeper red glow than the Ultronics tubes which are more orange. Perhaps a different amount of mercury in it. Someday when I think about it I'll test it again.

[Nicholas Stock]

I have a MOD_6 with pin-top tubes in them. Absolutely no visual difference to the non-pin ones when compared side by side.

Jeff, you should have bought more when you could!!!! 😀

I still rue the day when I thought a box of 100 IN14's at $99 was expensive.....

Nick

Sent from my iPhone

On Jul 6, 2023, at 07:34, Robert G. Schaffrath <robert.s...@gmail.com> wrote:

I have one of the pin top tubes (https://n2jtx.com/NixieClock/Used%20Burroughs%20B-7971.jpg). Unlike most of my other tubes, it is a Burroughs branded tube and not Ultronics. The only thing I ever noticed different about it was it seemed to have a deeper red glow than the Ultronics tubes which are more orange. Perhaps a different amount of mercury in it. Someday when I think about it I'll test it again.

To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/7e3257e3-e81f-4f76-b97e-9d564641af74n%40googlegroups.com.

[Michail Wilson]

Same here.

I have 5x MOD_6 clocks (various versions).  2 with ‘antenna’ tubes. I notice no difference; however, I pride myself on having the antenna tubes.  Maybe it was just me, but having had hundreds (if not a thousand) of B7971 tubes, I have only run across the 13 antenna tubes  (yes, only 1 spare).

 

Michail

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[Robert]

I’ve seen 12 of these tubes and two have had the top pin antenna 

Thanks

Rob

On 6 Jul 2023, at 16:20, Michail Wilson <M...@michail.com> wrote:



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