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DK32

Sensibly equivalent to:
1A7G 1A7GT CV1802 X14
    
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The DK32 is a heptode frequency changer designed for battery superhet radio receiver use. Ever Ready made valves in the early days but remained a major supplier of batteries both LT and HT up until the end of the valve receiver era. This exhibit was probably made by Mullard.
As a frequency changer, the local oscillator is formed between the cathode and grid 2. Grid 1 being the oscillator control grid. The pulsating electron flow is screened by Grid 3 from the oscillator and grid 5 from the anode. In this screened space is the mixer control grid g4. For maximum isolation between oscillator and signal circuits the mixer control grid is taken to the top cap.
The signal grid, g4, is taken to the top cap for maximum isolation from the oscillator circuit that would be located beneath the chassis.
This photograph shows the grids. Note that g2, the oscillator anode, is just the two stout rods.
The wide glass tube envelope is 30 mm in diameter, and excluding the IO base pins is 85 mm tall.
References: Datasheet, 1040, 1043 & 3002. Type DK32 was first introduced in 1945.

 

Pin Connections
IO
1
2
3
4
5
6
7
8
tc
s
f+
a
g3,g5
g1
g2
f-
-
g4

 

Absolute Maximum Operating Conditions
Heptode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
1.4
0.05
110
60
-0
0.6
0.7
0.6M
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated February 08, 2013.
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