Downloaded from https://www.everyspec.com MIL-STD-1311D CONVERSION TRANSCONDUCTANCE Conversion transconductance shall be determined from measurements of the magnitude of a single-beat frequency component (F' - F") or (F' + F"), of the output current, and of the magnitude of the input voltage of frequency F', and shall be within the limits specified.
The standard method of measurement of conversion transconductance shall be by application of 60-Hz voltages of identical phase and frequency from a source of less than 100 ohms impedance, to the specified electrodes, such as the signal and oscillator grids, with provisions for a phase reversal of 180 ° of one with respect to the other (see figure 1326-1). The time constant of the grid-coupling capacitor (C1) and grid-resistor (R1) at the oscillator grid-signal frequency (F 0 ) shall satisfy the equation METHOD 1326A . 16 .0 1 1 1 = C R Fo The change in dc anode current due to the phase reversal represents the difference frequency anode current component.
The rms value of the signal frequency voltage shall be 0.354 volt. The quotient of the change in anode current and twice the peak value of the sinusoidal voltage applied to the signal input electrode shall be the conversion transconductance. Specified operating potentials shall be applied to the tube, and the oscillator injection voltage shall be adjusted to the specified oscillator grid current.
Ba - Bucking battery M4 - dc microammeter (low resistance) Ch - Choke (filter) incremental anode current C1 - Coupling capacitor M5 - dc milliammeter (anode current) C2 - Capacitor (filter) R1 - oscillator grid resistor Eac - 60 Hz supply (sinusoidal) R2 - Rheostat (bucking current) M1 - Voltmeter (signal) SW - Reversing switch M2 - Voltmeter (Oscillator injection) T1, T2 - Isolation transformers M3 - dc microammeter (oscillator grid current) T3, T4 - Variable auto transformers FIGURE 1326-1. Conversion transconductance test. METHOD 1326A 1326-1 25 March 1970