Siemens/Telefunken frame-grid pentode with very similar characteristics and application (coaxial repeater amplifier) — different Loctal base variant, not pin-compatible
Electrical Specifications
Section 1 — Pentode
Absolute Maximum
Anode Voltage (max)Maximum Direct Anode Voltage250V
Screen Voltage (max)Maximum Direct Screen Voltage150V
5A/152G is the wire-ended version of the same tube, not a base variant.
Pin 5 is an internal metallic shield connection — not the same as the screen grid (g2, pin 3). This shield should typically be connected to ground or cathode for minimum noise.
The equivalent noise resistance of 670 ohms is exceptionally low for a pentode, comparable to the C3g.
Designed for 600-ohm telephone line repeater service; popular in high-end audio as a driver tube in triode-strapped mode.
The datasheet does not specify grid bias voltage, pentode-mode anode resistance, or maximum heater-cathode voltage. Grid bias must be determined from the published anode characteristic curves.
Triode-strapped data is not from the manufacturer datasheet. μ=40.7 from a Koren SPICE model fitted to plate curves (diyAudio user 'Koonw'). ra≈2.3 kΩ and gm≈17.7 mA/V estimated by analogy with the C3g (Siemens TFK datasheet: μ=41, ra=2.3 kΩ in triode mode) — multiple sources report the 5A/152M has curves 'pretty much the same as the C3g'. Both tubes were designed for the same coaxial repeater application.