CH1

The CH1 is a variable-gain hexode for frequency conversion and radio-frequency or intermediate-frequency amplification. As a mixer it requires a separate oscillator: Tungsram, which calls it TCH1, proposes the TCC2. Its heater requires 13 V and 0.2 A; the cathode is indirectly heated. Philips describes use in AC/DC receivers with heaters in series or parallel. The European base has eight side contacts; the first grid connects to the top cap, while the third receives the oscillation in mixer service. Philips’ 1935 documentation relates it to AH1 while distinguishing heater ratings. The sheet of 19 March 1940 gives maximum height 110 mm and diameter 46 mm.

For conversion, Philips in 1940 gives a point with anode at 200 V, second grid at 100 V, fourth at 50 V and third at −12 V, with 9 V RMS oscillation. With first grid at −2 V, anode current is 2.2 mA, conversion transconductance 550 µA/V and internal resistance 2 MΩ. Moving the first grid to −24 V reduces current below 0.015 mA and conversion transconductance below 2 µA/V, while internal resistance exceeds 10 MΩ. This illustrates the wide gain-control range. In amplifier service, however, the third grid is controlled together with the first: at the same anode and screen voltages and −2 V bias, anode current is 4 mA and transconductance 2 mA/V. These figures describe different functions and are not interchangeable.

The Philips 1940 sheet allows 250 V anode voltage and 1.5 W anode dissipation; each screen, g2 and g4, is rated at 125 V and 0.5 W. Cathode current is limited to 10 mA. Maximum grid-leak resistances for g1 and g3 are both 2.5 MΩ; external resistance between heater and cathode must not exceed 5 kΩ. Listed capacitances are 6.9 pF input and 15.3 pF output, with less than 0.25 pF between g1 and g3 and less than 0.003 pF between g1 and anode. Editions also require attention: the 1935 Philips catalogue gives 2.4 mA anode current for a conversion point with 200 V anode, whereas the 1940 sheet gives 2.2. Keeping the specific table reference avoids combining values from different documents into a single assumed characteristic.