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Mullard: Series Operated 100mA B9A Range of valves for VHF/FM
Designed so that the heaters are wired in series at 100mA, this set of valves was issued in 1954/5 to cope with the burgeoning VHF/FM demand as the UK went high frequency.  Briefly the set consists of;
UCC85 Useful for the front end of the VHF radio as one triode can be used for and RF amplifier, and the other as an oscillator / mixer.
UCH81 Designed to be used as the AM IF amplifier (the triode) and first stage FM IF amplifier.
UF89 Flexible valve in its own right but commonly used for second and third stage IF amplifiers.
UABC80 Four sections, two diodes that can be used as an FM ratio detector,  the third diode can be switched to an AM signal detector and the final triode used as an audio amplifier.
UL84 Final audio amplifier valve for over 5W output.
UY85 Rectifier for mains powered radios.


Valve Data: UCC85

VHF Double Triode
(Data taken from Mullard Valve Data sheet)

0.1A, 26V Heater
Noval B9A base

Equivalents: 10L14, 28AQ8, B109

Vh 26V 48 gm 5.8 mA/V
Ih 100mA -Vg 2.1V Ra 8.3k ohm
Va 200V
Ia 10mA

Valve Data: UCH81

High Frequency Triode Heptode Frequency changer
(Data taken from Mullard Valve Data sheet)

0.1A, 19V Heater
Noval B9A base

Equivalents: 10C14 19AJ8, 19D8, X119

Triode Heptode Triode Heptode Triode Heptode
Va 170V 200V Ia 4.5mA 5.4mA Ra 6K ohm 1m ohm
-Vg1 0V 2.6V Ig2 --- 8.1 mA Rk --- 150 ohm
Vg2 --- 119V Ig3 --- 230uA Rg2 --- 10k ohm
Vs --- 119V gc 0.750 mA/V 0.775 mA/V Rg3 --- 47k ohm
Rgt 47K ohm

Valve Data: UF89

HF Pentode Variable-mu Amplifier
(Data taken from Mullard Valve Data sheet)

0.1A, 12.6V Heater
Noval B9A base

Equivalents: 12DA6

Vh 12.6V Vg2 110V gm 3.8 mA/V
Ih 100mA Ig2 3.9mA Ra 0.53m ohm
Va 170V -Vg1 2.0V
Ia 12mA

Valve Data: UABC80

Triple Diode Triode
(Data taken from Mullard Valve Data sheet)

0.1A, 28V Heater
Noval B9A base

Equivalents: 10LD12, 28AK8, DH109

Vh 28V 70 gm 51.4 mA/V
Ih 100mA -Vg 2.3V Ra 50k ohm
Va 200V
Ia 1mA

Valve Data: UL84


Audio Output Pentode
(Data taken from Mullard Valve Data sheet)

0.1A, 45V Heater
Noval B9A base

Equivalents: 10P10, 10P18, 45B5, 45BQ5, N119

Vh 45V Vg2 200V gm 8.8 mA/V
Ih 100mA Ig2 4.1mA Ra 8.0k ohm
Va 200V -Vg1 17.3V Pout 5.2W
Ia 60mA Rg2 470 ohm Pa max 12W

Valve Data: UY85

Half Wave Rectifier (indirectly heated)
(Data taken from Mullard Valve Data sheet)

0.1A, 38V Heater
Noval B9A base

Equivalents: 38A3, U119, U381

Vh 38V
Ih 100mA
Va max 250Vrms
Iout max 110mA