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BU28/4

Sensibly equivalent to:
CV5003
    
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We have no details on this Barretter. Measurements show that the iron wire connects between pins 2 and 7 - the standard heater connections for octal valves. The cold resistance is 5.9Ω.
Ralph has found details of a BU29/4 in edition 7 of the Wireless World data book. Neither is listed in the eighth edition. The Type designation seems to suggest the rating. The best guess is that a current of 0.285 Amps is stabilised for voltage drops of between 2.5 - 6.0 Volts.
The wire is looped over a single central support.
The wire is a single strand.
Thanks to Ralph Rayner for donating this exhibit.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins is 83 mm tall.
Reference: Observation.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
-
f
-
-
-
-
f
-

 

Updated January 06, 2016.
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