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Valve Data: Osram 6.3V A.C. Miniature Range of Valves for AM Radios

Designed so that the heaters are all supplied 6.3V these miniature valves were ideal for the period's shrinking radios. To the right you can see their useful advertisement from the "Wireless and Electrical Trader"  of 21st July 1951.  Briefly the set consists of;

X79 - For front-end use, a triode hexode frequency changer
W77 - Their R.F. remote cut-off pentode perfect for IF amplification
DH77 - Double diode triode for signal rectifying
N78 - Output pentode to drive the speaker.
U78 - Rectifier for mains powered radios.

The valves were all B7G except the X79, being a B9A.

Osran Advert from 1951

Valve Data: X79

Triode Hexode Frequency Changer
(Data taken from Osram Valve Data sheet)

0.3A, 6.3V Heater
B9A base

Equivalents: 6AE8, V5115

Pin 1 Gs gc 0.78 mA/V
Pin 2 Gc Va 250V
Pin 3 C Vs 100V
Pin 4 H
Pin 5 H
Pin 6 A
Pin 7 Go
Pin 8 Ao
Pin 9 IC

Valve Data: W77

R.F. remote cut-off (variable mu) pentode
(Data taken from Osram Valve Data sheet)

0.2A, 6.3V Heater
B7G base

Equivalents: 9D6, EF92, 12K7GT, KTW74M, 6CQ6, 6F21, 6065, M8161, CV131, CV4015, CV8017

Pin 1 Gc Ra 0.5m ohm
Pin 2 C gc 2.5 mA/V
Pin 3 H Va 250V
Pin 4 H Vs 250V
Pin 5 A
Pin 6 Ge
Pin 7 Gs

Valve Data: DH77

Double Diode Triode
(Data taken from Osram Valve Data sheet)

0.3A, 6.3V Heater
B7G base

Equivalents: EBC90, 6AT6, 6BT6, 6066

Pin 1 Gc Ra 58k ohm
Pin 2 C gc 1.2 mA/V
Pin 3 H Va 250V
Pin 4 H ? 70
Pin 5 D2
Pin 6 D1
Pin 7 A

Valve Data: N78

Output Pentode
(Data taken from Osram Valve Data sheet)

0.64A, 6.3V Heater
B7G base

Equivalents: 6BJ5, CV3711

Pin 1 Gc Ra 40k ohm
Pin 2 C, Ge gc 10.5 mA/V
Pin 3 H Va 250V
Pin 4 H Vs 250V
Pin 5 A
Pin 6 IC
Pin 7 Gs

Valve Data: U78

Indirectly heated bi-phase rectifier
(Data taken from Osram Valve Data sheet)

0.6A, 6.3V Heater
B7G base

Equivalents: 6X4, EZ90, 6BX4, 6Z31, 5993, 6202, CV493, CV3734, CV4005, CV5185, CV8203, CV8223, CV8237

Pin 1 A2 Ra 40k ohm
Pin 2 nc gc 10.5 mA/V
Pin 3 H Va 325+325V rms max
Pin 4 H Io 70mA
Pin 5 nc
Pin 6 A1IC
Pin 7 C