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SP61

Sensibly equivalent to:
ARP36 CV118 CV260 CV1065 VR65
See also:
Valves and their Habits - SP61 SP41 P61 & P41 Advert - A Magnetic Digital Storage System - Electron Tubes for the Transatlantic Cable System
    
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The SP61 was a commercial television RF pentode that became adopted by the military during WWII. We have several variants in the collection, but this is the original livery of the manufacturers and is covered by an external screening metallisation. For mixer use a separate low noise oscillator was designed this was the P61 also known as the VR66.
A special batch, made in 1942, was the source of valves for the Anglo-Irish undersea telephone repeater cable laid in 1944.
With the grid at the top cap, this is the normal pattern for RF and IF amplifier valves of the period. Providing high gain in tuned anode circuit applications.
The rear of the envelope is just plain zinc paint.
Little detail is revealed by looking into the top.
The classic envelope is 32 mm in diameter and, excluding the MO (Mazda Octal) base pins, is 81 mm tall.
References: Data-sheet, 1043 & 1040. Type SP61 was first introduced in 1941.

 

Pin Connections
MO
1
2
3
4
5
6
7
8
tc
h
k
a
g2
g3
m
nc
h
g1

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
6.3
0.6
200
200
-1.5
10.9
2.7
0.7M
8.5
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated October 16, 2020.
shape:classic construction:pinch type:pentode age:1940.1950 base:mo heater:6.3v pins:8 pin:1.h pin:2.k pin:3.a pin:4.g2 pin:5.g3 pin:6.m pin:7.nc pin:8.h pin:tc.g1
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