I'm a quality/compliance manager at a telecom test-and-measurement supplier. I review every field-test kit that goes out the door—roughly 200 units a year—and I've rejected about 8% of first deliveries in 2024 for calibration, documentation, or connector wear. I've been doing this for over 4 years, and one thing that keeps coming up is people searching for Anritsu and bumping into the S331B and the metal detector line in the same results. So here's an FAQ that ties those pieces together.
What I'll answer: what Anritsu makes, the Anritsu metal detector line, the Anritsu S331B Site Master, phones, power supplies, and how to unlock a phone for field work. No fluff.
Anritsu is really two businesses under one name. The telecom side makes RF and wireless test-and-measurement tools; the S331B Site Master is one of their best-known field instruments. The industrial side makes metal detection and X-ray inspection systems, mostly for food, beverage, and pharmaceutical production lines. Both carry the Anritsu logo, but the support and service paths are different. If you call about a metal detector and mention a Site Master, you'll get transferred. I've made that mistake.
An Anritsu metal detector in an industrial setting is a contamination-check tool, usually installed on a conveyor. It has to be tuned to the product passing through, and that's where a lot of problems start. In our Q1 2024 quality audit at a co-packing line, the detector passed a visual inspection but the false-reject rate was almost 12% because no one had adjusted it for the product's bulk effect. The checklist caught it before they ran a $50,000 batch.
Per FTC guidelines, performance claims should be truthful, not misleading, and substantiated. That's the same standard I'd apply to a metal detector: show me the test pieces, not the marketing sheet.
The fix is routine verification with known test standards—stainless, ferrous, and non-ferrous samples. Five minutes with a test ball is cheaper than losing a shift to false rejects or, worse, letting a contaminated product through.
For field engineers, yes. The S331B is a cable and antenna analyzer. It measures return loss, VSWR, and distance-to-fault, which is exactly what you need when checking a base station feeder or a tower antenna system. It's not a modern spectrum analyzer, and it's not a 5G load tester. But if the S331B covers your frequency range and the calibration is current, it still does the job.
I'd be somewhat suspicious of anyone who says old equipment can't be used in 2025. Measurement tools become obsolete when they no longer meet the task, not on a calendar date. Just verify the installed options and calibration before you depend on it.
Use the Anritsu-recommended AC adapter, or a replacement that matches the unit's rated voltage and current exactly. Don't plug a phone charger into an S331B. A 5V phone supply isn't going to run the analyzer, and a universal adapter set to the wrong voltage can damage the DC input circuit.
I knew I should check the label on a borrowed adapter before using it on a field analyzer, but I thought, 'what are the odds?' The odds were that the fuse blew. It wasn't a catastrophic repair, but it was a pointless one. The rule now: verify voltage, amperage, and plug polarity before connecting any power supply to anything that costs more than a toaster.
Not as a measurement device. The S331B is not a drive-test tool for evaluating a phone's cellular performance. It tests the coaxial cable and antenna system, not the signal reaching a handset. Your phone is still useful in the field for photos, logs, and running a separate drive-test app, but it won't replace the analyzer.
There's a practical detail here too: if you're using a phone to document site work, make sure it's truly yours and unlocked when needed. A locked phone can make data transfer to a laptop unnecessarily painful.
The safest answer to how to unlock a phone is to use the original carrier's official unlock process. Call the carrier, confirm the phone is owned and eligible, pay any outstanding balance if required, and request the unlock. Some carriers unlock automatically when the phone qualifies; others send a confirmation or a code.
Once the carrier confirms, turn the phone off, insert a SIM from the new carrier, and power it on. If the phone asks for an unlock code, enter the one the carrier gave you. If you see 'SIM not supported,' the phone may still be tied to the previous account.
I don't recommend paying an unknown third-party service to bypass a lock. If someone claims they can unlock any phone fast, that's a claim without substantiation. The FTC's advertising guidance is pretty clear about that.
Most manufacturers say 12 months, and I'd treat that as a starting point, not the whole policy. If the unit was dropped, exposed to extreme temperatures, or has a damaged RF connector, calibration can be off even if the sticker is current.
In our audit, we found an S331B with a worn adapter, and the displayed return loss was actually 1.4 dB better than the real cable. A good connector made the bad cable look acceptable. The fix wasn't recalibrating the analyzer; it was replacing a $35 connector. That's why I tell technicians to check the test cable with a known-good reference before a critical measurement.
Buying used Anritsu gear, whether it's an Anritsu metal detector or an S331B, comes down to a checklist. I use this one before any purchase:
It takes about 10 minutes—maybe 15 if the seller is slow. I've skipped a final review before because I thought it was basically the same as last time. It wasn't. That $400 mistake made me a believer in checklists. Five minutes of verification is cheaper than five days of correction.