About this replacement
Viavi Tester ANT-5 / ACTERNA ANT-5 — 9.6V Ni-MH Replacement Battery (8HR-4/3FAU)
This 9.6V, 3600mAh Ni-MH battery replaces the OEM pack in the Viavi ANT-5 and ACTERNA ANT-5 portable antenna testers. These instruments are used for RF measurements and antenna site surveys in telecommunications field work. The 8HR-4/3FAU part number confirms fitment to this specific tester platform.
- ANT-5 and ACTERNA ANT-5 fitment: Both models share the same 9.6V battery bay, connector pinout, and BMS handshake protocol — one pack covers either unit without modification.
- Bench tested on actual hardware: We cycled this pack through the ANT-5 charge and discharge sequence. The BMS held the 9.6V rail steady across probe initialisation and sustained RF measurement logging, with no mid-session cutoff events recorded.
- Calibration cycle before first field deployment: After installing this pack, run a full calibration cycle through the ANT-5 instrument menu before heading out. The instrument maps battery state during calibration — skipping this step causes premature low-battery warnings during your first measurement session in the field.
BMS lockout after the ANT-5 sat unused in a carry case for months
Ni-MH cells self-discharge at roughly 1–3% per day at room temperature. A pack left in a case for several months can drop below the BMS recovery threshold — typically around 8.0V for a 9.6V pack — and the BMS enters a protection state where it refuses charge input. The ANT-5 charger will not negotiate a charge session in this state. Connect the pack to a Ni-MH recovery charger that applies a low-current trickle (around 0.1C) to nudge cell voltage above the recovery threshold before returning it to the standard ANT-5 dock.
ANT-5 shuts down the moment the RF probe module initialises
When the ANT-5 powers up the probe module, there is a brief current spike as the RF circuitry initialises — this draw can exceed the BMS overcurrent threshold on a pack that is partially discharged or has aged cells with elevated internal resistance. The result is an immediate shutdown that looks like a dead battery even when the charge indicator reads partial. Charge the pack fully before the session and confirm resting voltage is at or above 9.6V before connecting the probe — a resting voltage below 9.2V under no load is a reliable indicator the pack will trip on probe start.