1M3

1M3 is also designated DM70.

Description

The 1M3 is a subminiature tuning indicator tube with a directly heated filament. It is designed for use in FM tuners where accurate tuning is desirable, and is also suitable for wire and tape recorders to indicate depth of modulation.

Ratings

The filament is directly heated and may be operated on A.C. or D.C., in series or parallel. The heater voltage is 1.4 volts and heater current is 25 mA. In battery receivers, the filament voltage is 1.4 V and current is 25 mA. For A.C./D.C. receivers, the filament voltage is 1.3 V. In A.C./D.C. receivers, the filament can be connected in a heater chain with a shunt resistor, provided an N.T.C. resistor is present.

The Miniwatt datasheet gives a maximum plate voltage of 150 V, a minimum plate voltage of 45 V, a maximum plate dissipation of 75 mW, a maximum cathode current of 0.6 mA, and a maximum grid resistance of 10 megohms.

Physical Characteristics

The maximum overall length, excluding pins, is 1 3/4 inches, and the maximum diameter is 0.4 inches. The tube has a miniature 8-pin base. The Amperex datasheet gives the socket as Amperex #S-19883.

Equivalence is asserted only where the archive's own literature states it directly, in at least 40 separate documents. Tubes that merely substitute in some circuits are not listed here.

Original manufacturer datasheets for 1M3, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• "Miniwatt" (filed under DM70)
• 1M3

1 further designation appears alongside 1M3 in the literature but below the evidence threshold used here, so it is not listed as equivalent.