Raytheon 7978 & 8262 Dekatron Tubes  
Written by AnubisTTP on 2009-01-23  



Devices included in this entry:

Raytheon 7978 selector (13-pin compact base)
Raytheon CK8262 selector (engineering sample,13-pin compact base; pictured in thumbnail)

Though Raytheon manufactured many second source variants of Sylvania dekatrons like the 6802 and 6910, Raytheon developed few new dekatron part numbers themselves. The hard to find 7978 and nearly unobtainable 8262 are the only two dekatrons existent that were manufactured exclusively by Raytheon. With the exception of its pedigree the 7978 is otherwise a fairly standard neon filled compact dekatron, it operates in a conventional double pulse fashion and counts at 5kHz. The tube's electrical characteristics are very similar to a Sylvania 8353, though its envelope and pinouts are different. The 7978 tube is substantially rarer than an 8353 however, and heavily sought by collectors seeking a example of a Raytheon-manufactured tube.

The 8262 is Raytheon's high-speed counterpart to the 7978, it's strangly colored mixed-gas fill is responsible for the tube's brisk 100kHz counting speed. The 8262 is so rare as to practically only exist in the annals of tube lore, but as a counting device it is probably best left to the crushed velvet shelves of tube collectors. Raytheon's high speed decade counter gas has a notorious habit of vacating a tube's envelope long before the tube falls in the hands of a modern hobbyist, which makes the 8262 an extremely poor choice for a dekatron-themed project.

Raytheon 7978 Datasheet (PDF)


Raytheon 8262 Dekatron Tube
Raytheon 8262 compact envelope dekatron tube.

Raytheon 8262 Dekatron Tube
This particular example of the 8262 is a rare engineering sample variant.

Raytheon 7978 Dekatron Tube
Raytheon 7978 compact envelope dekatron tube.

Raytheon 7978 Dekatron Tube
The CK7978 and CK8252 are the only two glow transfer counting tubes that were manufactured by Raytheon exclusively. Other Raytheon counting tubes are originally of Sylvania origin.

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