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VP4

Sensibly equivalent to:
A50M AC/VP1 CV3788 MVSPen VP4A VPT4B
See also:
Mullard SP4 & VP4 Advert
    
Extras ▼

 

The VP4 is a variable μ RF pentode that was introduced in 1933 on the B5 base. A year later the B7 base version was introduced.
The gain is controlled by altering the bias on the control grid, normal operation is with the bias ranging from -2 to -22 Volts. In a superhet receiver this variation would be derived from the rectified voltage at the end of the IF chain (AGC). The stronger the signal the greater the rectified voltage and this the more negative the control grid is driven and that in turn reduces the amplification of the VP4 in the IF stage.
Both images have been sent by Mike and this shows a VP4 minus the external metalisation paint. The mesh anode and suppressor grid can easily be seen, the screen grid is just visible.
The classic envelope is 50 mm in diameter, and excluding the base pins is 122 mm tall.
References: Datasheet & 1043. Type VP4 was first introduced in 1933.

 

Pin Connections
B5
1
2
3
4
5
tc
g2
g1
h
h
k,g3
a

 

Absolute Maximum Operating Conditions
Pentode
Vh
Ah
Va
Vs
Vg
mAa
mAs
ra
gm
μ
4.0
1.0
200
100
-2
4.5
1.9
1.0M
2.3
Thanks to Andy Cowley for supplying the above PDF datasheet.
Updated August 11, 2013.
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