This triode-pentode with separate cathodes and a 0.3 Amp heater, for use in AC/DC equipment, has a number of advantages over other mixer-oscillator valves designed for similar applications.
The high slope (8.5 mA/V) of the triode section permits the required oscillator voltage to be obtained with the minimum generation of oscillator harmonics and a low value of oscillator grid current.
Although it is necessary to have a high conversion conductance available for BAND 3 reception, this parameter is not so important as at low frequencies. One of the other factors which is of importance is the input impedance and its variation with frequency and bias voltage. The Brimar PCF82/9U8 has a high input impedance pentode which maintains an appreciably constant tuner gain over BANDS 1 and 2. The low anode-grid capacity of the pentode (.006 pF max.) and low pentode anode-triode anode capacity helps to keep the oscillator radiation to a minimum. Very low variation of conversion conductance is obtained by the use of combined grid leak and cathode bias.