Three valves,

Valve # 1, 2 and 3:
Remote cut-off pentode for radio frequency (RF) and intermediate frequency (IF) amplification in battery powered radios. Replaced by the octal equivalent 1M5-G in about 1938. 2 V directly heated cathode.

Valve # 3:
Valve is screened from interaction with other valves and stray signals

Physical Description

Shouldered glass bulb with top cap and American 4 pin base (Valve # 1). Mounted on display block with a sectioned example of the same type (Valve # 2). Valve # 3: Shouldered bulb with four pin UX style base with top cap, encased in rusty metal screening can ('goat shield').

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