ECC40 Triode Vacuum Tube
Medium-gain triode for voltage amplification applications
Philips, Eindhoven
Philips sheets dated 1951.02.02, 1951.06.06, 1953.10.10; index page 1999.04.19 · 8 pp · EN · FR · DE · NL
Most complete manufacturer set: capacitances, applications, limiting values, two characteristic graphs, microphony note.
Philips English reprint
1966-11-11; page codes 7Z2 6996-7000 · 6 pp · EN
Quick reference, heating, pinout, typical point, output valve, push-pull, phase inverter, LF amplifier, limiting values, Ia/Va curves.
La Radiotechnique (Suresnes, Philips subsidiary)
12-1951 · 4 pp · FR
French nominal data, capacitances, BF amplifier table, limits, dimensions and both transfer/anode-curve graphs.
CIFTE / Mazda
I-1968 · 3 pp · FR
Nominal data, capacitances, pinout and anode-curve page; useful for late French/Mazda variant cross-check.
Philips Technical Article
Manufacturer-agnostic abstract · 1 pp · EN
Long-form descriptive article: general description, microphony guidance, AF amplifier use, output valve (SE + push-pull), three phase-inverter circuits (A/B/C), saw-tooth blocking oscillator, electronic counter flip-flop, with figure captions for curves 12-15.
| Capacitance | Philips · Section I | Philips · Section II | Radiotechnique | CIFTE / Mazda |
|---|---|---|---|---|
| Cg | 2.8 pF | 2.6 pF | 2.8 pF | — |
| Ca | 1.1 pF | 0.55 pF | 1.1 pF | — |
| Cag | 2.7 pF | 2.8 pF | 2.8 pF | — |
| Cgf | <0.1 pF | — | — | — |
| Ckf | 3 pF | — | — | — |
| Ce | — | — | — | 2.8 pF |
| Cs | — | — | — | 1.1 pF |
| Cg_a | — | — | — | 2.6 pF |
| Vb | Ra | Ia | Gain | Vo max | dtot |
|---|---|---|---|---|---|
| 400 V | 47 kΩ | 4.1 mA | × 21 | 72 Vrms | 4.4 % |
| 350 V | 47 kΩ | 3.6 mA | × 20 | 60 Vrms | 4.1 % |
| 300 V | 47 kΩ | 3.1 mA | × 20 | 50 Vrms | 4 % |
| 250 V | 47 kΩ | 2.6 mA | × 20 | 40 Vrms | 3.8 % |
| 200 V | 47 kΩ | 2 mA | × 20 | 30 Vrms | 3.4 % |
MU=31.92 EX=1.33 KG1=591.1 KP=1997.6 KVB=6269.5 VCT=0MU=30 EX=1.33 KG1=634.9 KP=1997.6 KVB=6269.5 VCT=0MU=30 EX=1.33 KG1=634.9 KP=1997.6 KVB=6269.5 VCT=0MU=31.92 EX=1.33 KG1=591.1 KP=1997.6 KVB=6269.5 VCT=0Ia vs Vg at Va = 250 V — each manufacturer Koren fit overlaid. The de-rated French families (μ=30) read lower than the Philips/1966 high-gm family (μ=32) at the same grid voltage.
Verbatim excerpts from the four manufacturer datasheets. Expand each section to read the original text — the Philips technical article carries the richest application content.
Source datasheets
4 manufacturer datasheets cross-checked for ECC40
The ECC40 is an indirectly heated double triode (6.3 V / 0.6 A) on the Philips B8A Rimlock 8-pin side-contact base, published 1951–1953 by Philips and reprinted in English through 1966. The two sections are wired with separate cathodes and share only the heater; the datasheet operating point is Va = 250 V, Vg ≈ −5.6 V, Ia = 6 mA per triode. Published parameters split into two manufacturer families: Philips/1966 give μ = 32, gm = 2.9 mA/V, rp = 11 kΩ; the French La Radiotechnique (1951) and CIFTE/Mazda (1968) editions publish μ = 30, gm = 2.7 mA/V at the same rp. Limits per triode are 300 V plate, 1.5 W plate dissipation, 10 mA cathode current, and an asymmetric 175 V (f−/k+) / 100 V (f+/k−) heater-to-cathode rating that earned the ECC40 its use in elevated-cathode phase inverters. The datasheet covers single-ended Class A output (280 mW into 15 kΩ at 8.5 % dtot), Class A push-pull (520 mW into 30 kΩ Raa at 1.0 % dtot), LF voltage amplification across Ra = 47 / 100 / 220 kΩ × Vb = 200…400 V, two-section cascade with gain 740–780, three phase-inverter circuits, and saw-tooth blocking-oscillator + flip-flop service for early electronic counters. The Rimlock base was retired in favour of the 9-pin Noval (ECC81/82/83) within a decade, which is why surviving NOS Philips, Mullard, Valvo and Mazda examples now read as collector pieces rather than a current-production part.