On Nov 18, 7:32 am, Accutron <[email protected]> wrote: > The Martin Company was an aircraft manufacturer - the same Martin that > would end up as part of Lockheed Martin. They also produced missiles > and other military stuff. The tubes are probably replacement parts for > a Martin aircraft display, or were possibly used as part of the > Project Vanguard rocket program, which was going on in the late 1950s. > > Do the boxes have a USAF contract number? The contract number would > provide a base of origin and you might be able to find out the exact > program.
Just found a box of GI-21s, NIB. They are dated 5/60 or 6/60 and have a label which reads: 5960-552-0265 ELECTRON TUBE 1 EACH ITEM 1-2498 7901-PP-60-54-54-GFP THE MARTIN COMPANY GI-21 P/N SM-C-209280-1 EXPORT PACKING AND CRATING Co., INC. A IIIX 6/60 The end of the box is printed (not on a lable, on the box itself) with: NU GI-21 MADE IN U.S.A. The digits are stacked (looking from the top) 0,9,8,7,6,5,4,3,2,1 There is no anode as all unused digits are used as anodes by means of tying them each high with a high value resistor (typically 330K) and then pulling the digit you wish to light low. The advantage of this is that no anode mesh is required, so no patent infringement. Downside is the need for 9 extra resistors (10 needed vs. 1 if you have a single anode). The GI-10 patent, #2,769,939 - Charles R Williams, Northrop Aircraft Inc., (granted) November 6th 1956 (application) June 12th 1950 covers this well... Interestingly, a major claim of this patent is that the current draw of the tube is substantially reduced (to about 1mA). Nick -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To post to this group, send an email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/neonixie-l?hl=en-GB.
