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5B/254M


The John Lawrence Collection
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Sensibly equivalent to:- 5B/251M - CV428
 
See also:
Beam Tetrodes and the 807 - STC 5B/254M, 5B/255M, 5B/257/M & 5B/258M Advert - STC 5B/254M, 5B/255M, 5B/257/M & 5B/258M Advert
 
This exhibit was last updated on 18 February 2013
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The 5B/254M miniature beam tetrode was designed to have the same ratings as the classic 807. The difference in size between the 807 and this valve shows the extent to which valve technology matured during WWII and the effect of the introduction of the pressed glass base. This particular base was the earliest to be developed with eight equi-spaced pins and an external metal collar to hide the envelope seal and provide a locating spigot.
The valve is also very similar to the STC 5B/251M and electrically identical to the 5B/255M. The latter has the anode connected at the base and one less connection to the cathode.
The wide glass tube envelope is 30 mm in diameter and, excluding the B8B base pins, is 85 mm tall.
References: Datasheet & 1040. Type 5B/254M was first introduced in 1957.
 
Pin Connections
B8B
1
2
3
4
5
6
7
8
tc
h
k,bp
g2
k,bp
g1
g1
k,bp
h
a
 
Absolute Maximum Operating Conditions
Beam Tetrode
Vh
Ah
Va
Vs
Vg
mAa
mAs
Pdriv
Pdiss
Pout
freq
6.3
0.9
600
250
-45
100
8
0.3W
25W
40W
60MHz

Thanks to Frank Philipse for supplying the above PDF datasheet