KT66

Basing (pinout)

Bottom view — the socket as you see it from the wiring side. Hover, tap, or focus a pin to name it. Read from the datasheet basing diagram (how to read these →).

Datasheets

Primary manufacturer data, via public tube-data archives. The model below is fitted to the tabulated "average characteristics" in these sheets; the datasheet files themselves are linked, never rehosted.

Circuit Codex model

A CC0 ngspice model in the Koren form, fitted here to the published anchor — no parameters copied from other model collections. Methodology →

Anchor

Va=250 V, Vg2=250 V, Vg1=-15 V → Ia=85 mA, gm=7000 µmho (gm test point)

Source

GEC / M-O Valve Co. KT66 data sheet, Issue 4, April 1963

Note

µ is the grid-No.1-to-grid-No.2 amplification factor (9.5), from the triode-connection gm·ra on the same sheet. KG2 is anchored on the Class AB1 push-pull quiescent point (Vg2=300 V, Vg1=-27 V → Ig2=2.5 mA).

File

models/kt66.inc ↗

See these parameters drawn: the load line explorer plots the KT66's plate-curve family from this model and solves an operating point on it.

Maximum ratings

GEC prints two columns — a design maximum and an absolute maximum. The design figures are the ones a circuit is laid out against; the absolute column is the line beyond which the valve is out of specification. The 25 W design anode dissipation is what lets the KT66 sit where a 6V6 could not.

Anode voltage

500 V design · 550 V absolute

Screen (grid No.2) voltage

500 V design · 550 V absolute

Peak negative grid-No.1 voltage

200 V

Cathode current

200 mA

Anode dissipation

25 W design · 30 W absolute

Screen dissipation

3.5 W design · 4.5 W absolute

Anode + screen dissipation

27 W design · 32 W absolute

Grid-No.1 circuit resistance

1 MΩ cathode bias · 250 kΩ fixed bias (Pa+g2 ≤ 27 W)

Rating system

Design maximum — the line no individual valve may cross

Source

GEC / M-O Valve Co. KT66 data sheet, Issue 4, April 1963 — maximum ratings (design column) ↗