Heater-to-Cathode Voltage (max)Max Heater-Cathode Voltage90V
Max Grid Resistor
Notes
The A2900 is a GEC proprietary designation for a premium-grade ECC81 with tightly controlled section balance and low noise. It is functionally interchangeable with any ECC81/12AT7 circuit.
Also branded as Marconi A2900 (manufactured by MO Valve Company, England). CV6091 is the UK military designation for this high-reliability grade.
Some vendor sources claim the A2900 draws 0.4A heater current (0.1A more than standard ECC81). This is unconfirmed by manufacturer datasheets and likely refers to a specific variant or measurement anomaly. Standard ECC81 heater ratings apply.
Pin Layout — Noval
1Anode 2 (Triode section 2)
2Control Grid 2 (Triode section 2)
3
Socket-Compatible Tubes ⚠ Not electrically compatible