Voltage Pentode - Sharp Cutoff (single) ·Pentode
1221
Special low-microphonics version of the Sylvania 6C6 sharp-cutoff pentode, designed for receiver and amplifier stages requiring reduced mechanical noise. It uses a six-pin base and retains the electrical characteristics of the standard 6C6.
- Sections
- 1
- Base
- -
- Socket code
- -
- Base pins
- 6
- Nominal heater
- 6.3 V / 300 mA
General specifications
Tube and section characteristics
Properties common to every published source and operating point.
Heater and base
- Base
- -
- Socket code
- -
- Base pins
- 6
- Nominal heater voltage
- 6.3 V
- Nominal heater current
- 300 mA
- Parallel heater voltage
- -
- Parallel heater current
- -
- Series capable
- No
Terminal pinout
Electrical assignments shared by every tube using this base designation.
No verified pinout is recorded for this base designation.
Section ratings
1 physical section, each with unique specifications.
Section 1
Pentode
- Plate resistance
- 1500000 Ω
- Transconductance
- 0.001225 S
- Max plate voltage
- 300 V
- Max screen voltage
- 125 V
- Max plate dissipation
- 0.75 W
- Max screen dissipation
- 0.1 W
Sylvania 1221 special low-microphonics sharp-cutoff pentode electrically equivalent to 6C6, with six-pin base and 6.3 V 0.3 A indirect heater. Published 6C6 pentode service maxima: anode voltage 300 V, screen voltage 125 V, plate dissipation 0.75 W and screen dissipation 0.10 W. At the specified Va 250 V pentode operating point gm ~1.225 mA/V and plate resistance approximately 1.5 MΩ; these are typical, not limits. Manufacturer states 1221 non-microphonic construction differs from ordinary 6C6; interelectrode capacitances published for 6C6 and applicable by stated electrical equivalence.
Source-dependent data
Operating conditions by source
Each block preserves the test conditions and published values from one reference. Values from different sources are intentionally kept separate.