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VMP4G

Sensibly equivalent to:
CV1169 CV3785 CV3786 NR45
See also:
CV1169 short entry
    
Extras ▼

 

The VMP4G is a variable μ screened amplifier pentode for RF and IF amplification in superhet receivers.
The silvering on the glass prevents inspection. Originally the whole envelope was covered in a metal paint. This has broken off to reveal the etched identification applied to the glass itself.
We also have the Catkin version the VMP4K.
Here is another example of VMP4G where the zinc paint has fallen off to reveal the etched identification below.
On a remaining part of the external metalising can be seen the printed lettering.
Here the first two letters of Marconi survive on the external paint.
The lower shield with a gap for the electrodes. The insulated heater is easily seen.
The wire from the base that once connected the zinc paint to base pin one.
The classic envelope is 45 mm in diameter and, excluding the B7 base pins, is 118 mm tall.
References: Datasheet & 1043. Type VMP4G was first introduced in 1935.

 

Pin Connections
B7
1
2
3
4
5
6
7
tc
m
g1
g3
h
h
k
g2
a

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
gm
4.0
1.0
250
100
-2.0
8.0
5.0
2.7
Thanks to Frank Philipse for supplying the above PDF datasheet.
Updated April 06, 2015.
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