6AL5

6AL5 is also designated 5726, EB91, EAA91. Completed sales put the typical price at $9.00 per tube.

The 6AL5 is a miniature double diode with separate cathodes and internal screening between sections, intended for detection and phase-comparison service. It is a high-perveance tube comprising two diode elements with oxide cathodes that are indirectly heated, and can be used separately or in parallel in RF detection circuits, automatic volume control, or low-current rectification circuits.

Construction

The 6AL5 has an indirectly heated oxide cathode and a miniature 7-pin base, type 7C10. The tube includes an internal shield between the two diode sections, and an external shield with an internal diameter of 19.2 is connected to the filament. The internal structure is reinforced for high mechanical robustness and operational reliability, and the tube can be mounted in any position. The net weight is 6 g. The resonant frequency of each diode element is greater than 700 MHz.

Ratings

The filament is rated at 6.3 V and draws 300 mA, and may be powered in series or in parallel. The filament voltage tolerance is ±10%, and the filament current tolerance is ±1%. The maximum resistance between filament and cathode is 20 kΩ. The maximum voltage between filament and cathode is 150 V with the filament positive and 330 V with the filament negative. For each diode, the anode-to-cathode and filament capacitance is 2.5 pF, and the cathode-to-anode and filament capacitance is 3.4 pF; the capacitance between the anodes is 0.068 nF maximum.

In half-wave rectifier operation, the maximum anode voltage is 150 Veff, the maximum peak inverse anode voltage is 420 V, and the maximum anode resistance is 300 Ω. The maximum anode current is 9 mA, the maximum peak anode current is 54 mA, and the maximum rectified current is 9 mA. The maximum filter input capacitance is 8 μF.

Applications

The 6AL5 is specially intended for military and professional equipment. It was developed under contract from the Service Technique des Télécommunications de l'Air.

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.

Per-tube prices from completed sales, 2026-06-25 to 2026-09-14. Matched pairs and quads are divided out. See the price index for how these move over time.

Original manufacturer datasheets for 6AL5, hosted by Frank Philipse's Electron Tube Data sheets.

Documents held here and used to write this page.

• VALEURS LIMITES DES CARACTÉRISTIQUES POUR PROJETS D'ÉQUIPEMENT (filed under 5726)
• DVOJITÁ DIODA (filed under EAA91)
• 6 AL 5
• EB91 (filed under EB91)

2 further designations appear alongside 6AL5 in the literature but below the evidence threshold used here, so they are not listed as equivalent.