Professional Tube Laboratory Test Report
Every tube listed in my shop undergoes a rigorous testing procedure to ensure the highest fidelity and performance for your equipment.
- Testing Equipment: Professional Kalibr L3-3 Tube Tester.
- Precision Measurement: Measurements are verified using a calibrated Metrix MX 51EX digital multimeter.
- Transparency: All results are provided in the product photos, displaying specific Anode Current (Ia) and Transconductance (S) values compared to manufacturer specifications.
Why buy from us? Validated Quality (no guesswork, just documented performance) | Safe Shipping (double-boxed with anti-vibration materials) | Expert Service (specializing in high-end vintage electronics).
For sale is a museum-grade, historic vintage EL84 / 6BQ5 audio output power pentode (Internal Reference: TID6ZT), manufactured in France by La Radiotechnique (Suresnes) under strict military contract for the French Navy (Marine Nationale). This rare specimen comes with a classic original RT cardboard box in good vintage condition.
French Navy Military Provenance & Acid Etched Codes
This specimen represents the ultimate iteration of French military-grade electron tube manufacturing, carrying verified historical markings:
- Military Insignia: Official green French Navy Anchor (Marine Nationale) stamped directly on the glass, alongside a circled military acceptance badge "18".
- Internal Structure Marking: Secondary anchor insignia stamped above the upper mica spacer with code "00".
- Factory Acid Code: Permanent glass etching
bq 6743 — confirming production at La Radiotechnique Suresnes during the 43rd week of 1967.
Key Specifications
- Brand / Manufacturer: RT (La Radiotechnique France)
- Designation: EL84 / 6BQ5 Power Pentode (French Navy Military Spec)
- Condition: Vintage Used - Lab Bench Tested Outstanding
- Packaging: Classic original RT commercial box included (Good condition)
Detailed Test Results (Kalibr L3-3)
Test Voltages: Ua=250V | Ug2=250V | Ug1=-8.5V | Uf=6.3V
(Manufacturer specifications for a 100% brand new reference tube: Ia = 48.00 mA / S = 11.30 mA/V)
• Anode Current (Ia): 47.60 mA (99.2% of factory spec — Full power output)
• Transconductance (S): 10.06 mA/V (89.0% of factory spec)
Structural & Insulation Tests Passed
- Insulation test between Cathode (k) and Heater (H): PASSED (No leakage)
- Insulation test between Cathode (k) and Control Grid 1 (g1): PASSED (No shorts)
- Insulation test between Control Grid 1 (g1) and Screen Grid 2 (g2): PASSED (No leakage)
About our testing methodology
To provide full transparency, our laboratory testing uses a professional Kalibr L3-3 tube tester, cross-verified with a calibrated Metrix MX 51EX multimeter.
- Example of our calculation (Transconductance S):
Using a raw Metrix multimeter reading of 100.6 on a standard scale of 150 with a tester multiplier of 15:
(100.6 x 15) / 150 = 10.06 mA/V
- Percentage vs. Factory Specs:
We then benchmark this result against the manufacturer nominal value for a factory-new tube (11.30 mA/V):
(10.06 / 11.30) x 100 = 89.0% of factory specification.
Worldwide shipping with bulletproof packaging. Tracking number provided immediately.