Mullard Letter Symbols
and Abbreviations

1. Base and Connections:

        a               Anode
        B               Base
        C               Collector
        d               Drain
        E               Emitter
        f               Filament
        f+              Filament positive
        f-              Filament negative
        fct             Filament centre tap
        g               Grid, Gate
        h               Heater
        hct             Heater centre tap 
        htap            Heater tap
        IC              Internal connection (must not be connected
                        externally)
        k               Cathode
        M               Metallising (external) or base sleeve
        NC              No connection
        NP              No pin
        S               Internal shield, Source
        t               Fluorescent screen or target

NOTE 1 - In valves or tubes having more than one grid or anode, the 
electrodes are distinguished by numbers: g1, g2, etc., g1 being the 
grid nearest the cathode.

NOTE 2 - In multiple valves, electrodes of the different sections 
are distinguished by adding one of the following letters:

        Diode           d
        Triode          t
        Pentode         p
        Hexode  }
        Heptode }       h
        Octode  }

Thus the grid of the triode section of a triode pentode is denoted by gt.

NOTE 3 - Two or more similar electrodes which cannot be distinguished by 
any of the above means are denoted by adding one or more primes to 
indicate of which electrode system the electrode forms a part. Thus, the 
anode of the first diode in a double diode valve is denoted by a'.


2. Characteristics

        f               Frequency
        gc              Conversion conductance
        gm              Mutual conductance
        hfe             Small signal current amplification factor 
                        (common emitter)
        hFEL            Large signal current amplification factor 
                        (common emitter)
        Ia              Anode current
        ia(pk)max.      Maximum peak anode current
        Ia(av)max.      Maximum mean anode current
        IC              Collector current
        ICBO            Collector cut-off current (common base)
        If              Filament current
        Ig2             Screen-grid current
        Ig2+g4          Screen-grid current (frequency changers)
        Ih              Heater current
        Iout max.       Maximum output current
        It              Target current (tuning indicators)
        pa max.         Maximum anode dissipation
        Ptot max.       Maximum total dissipation
        P.l.V. max.     Maximum peak inverse voltage
        Pout            Power output
        ra              Anode impedance
        Ra              Anode load
        Tamb            Ambient temperature
        Va              Anode voltage
        va(pk)max.      Maximum peak anode voltage
        Vb              Supply voltage
        VCE             Collector-emitter voltage
        VCB             Collector-base voltage
        Vf              Filament voltage. D.C. forward voltage
        Vg1             Negative grid voltage
        Vg2             Screen-grid voltage
        Vg2+g4          Screen-grid voltage (frequency changers)
        Vh              Heater voltage
        vh-k(pk)max.    Maximum peak voltage between heater and cathode
        u               Amplification factor
        0j-amb  }        
        0j-case }       Thermal resistance


3. Other Abbreviations:

        Hz              Unit of frequency (formerly 1 c/s)
        kHz             Unit of frequency (formerly 1 kc/s)
        MHz             Unit of frequency (formerly 1 Mc/s)
        nF              Unit of capacitance (1nF = 0.001uF = 1000pF)

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