The Tool Desk
Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEFix the driver behind crashes, sound loss and screen glitchesFind Drivers →The Hameg HM 307 is a vintage, single-trace analog oscilloscope with a roughly 10 MHz vertical bandwidth and a built-in qualitative component tester. It can suit audio, low-frequency analog, power-supply and vintage-radio work if the individual unit is healthy. It is not a modern 15 MHz digital scope, and it is a poor choice for high-speed digital debugging or single-shot capture.
HM 307 specifications at a glance
| Specification | Documented value | Qualification |
|---|---|---|
| Type and display | Single-trace analog oscilloscope; round CRT of about 7 cm | Variant details can differ. |
| Vertical bandwidth | DC to 10 MHz at −3 dB | HM 307-4 documentation also lists 0–15 MHz at −6 dB. |
| Rise time | About 35 ns | Approximate specification. |
| Vertical sensitivity | 5 mV/cm to 20 V/cm | 12 calibrated 1–2–5 ranges. |
| Input impedance | 1 MΩ in parallel with about 25 pF | Verify against the manual for the exact revision. |
| Input coupling | DC, AC and ground | Panel markings may read DC–AC–GD. |
| Maximum stated input | About 500 V DC | Probe attenuation, frequency and voltage limits still apply; check the applicable manual. |
| Timebase | About 0.2 s/cm to 0.5 µs/cm | Some later documentation gives an uncalibrated extension to 0.2 µs/cm. |
| Triggering | Internal and external; positive/negative slope; automatic or adjustable level | Trigger-range figures vary by documentation, roughly 1–2 Hz to 25–30 MHz; this is not vertical bandwidth. |
| Calibrator | About 1 kHz square wave, 0.2 V peak-to-peak | Confirm on the individual instrument. |
| Component tester | Built in | Qualitative V/I display, not precision component measurement. |
| Power, size and mass | About 27 W; roughly 212 × 114 × 270–280 mm; about 3.7 kg | Values vary by variant and regional configuration; 27 W is listed for HM 307-4. |
| Mains | Regional/selectable arrangements include 110, 127, 220, 237 or 240 V | Inspect the rear selector and fuse before connecting. |
Specifications are compiled from the HM 307 manual scan, the HM 307-4 specification sheet, and model records at Radiomuseum and Doctsf. Treat the exact suffix and its corresponding documentation as authoritative for a particular unit.
What the Hameg HM 307 is
Hameg was a German test-equipment maker. The HM 307 is a compact, mains-powered CRT bench instrument intended for electronics service and hobby work. Historical model records place examples around 1976–1979, while period coverage appeared around 1980; exact production dates depend on revision and regional version. See the Radiomuseum record, Doctsf record and a January 1980 Wireless World advertisement.
It is single-trace: the display shows one vertical input signal at a time, rather than two independent channels. Controls are direct and largely analog, and its integrated component tester is a notable feature. Listings that call it a two-channel scope should be checked against the actual panel and manual; product references describe it as single-trace, including All About Circuits.
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Identify the exact variant before using a manual
Surviving labels and documentation include HM 307, HM 307-1, HM 307-2, HM 307-3 and HM 307-4. Not every suffix is equally documented, and front-panel nomenclature, wiring, mains arrangements and calibration procedures may differ. The HM 307-3 combined service and user manual is not automatically the right adjustment reference for an HM 307-4. The HM 307-4 specification sheet is specific to that later designation; a Radiomuseum HM 307-1 record documents another variant.
- Read the model and suffix from the chassis label and front panel.
- Photograph the front and rear panels, including the mains selector and fuse information.
- Match those details to the manual before calibration, repair or applying power to an imported unit.
What the bandwidth and trigger figures mean
The most useful general description is “10 MHz-class analog oscilloscope.” The conventional −3 dB point means a sine-wave amplitude has fallen to about 70.7% of its low-frequency value. Later HM 307-4 documentation also states 15 MHz at −6 dB, a point with greater attenuation; it should not be presented as equivalent to a 15 MHz scope rated at −3 dB.
Bandwidth is not a guarantee that every waveform at that frequency will be reproduced accurately. A waveform with fast edges contains higher-frequency harmonics, so the display can lose detail even when its repetition rate is below 10 MHz. The HM 307 is most at home with audio, low-frequency analog, power supplies, relay and motor-control circuits, and basic repetitive digital troubleshooting. It is not appropriate for confidently characterizing USB, Ethernet, HDMI, DDR, fast switching edges or modern signal integrity.
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Some documentation gives a trigger range extending to approximately 25–30 MHz and describes Hameg’s LPS triggering, intended to improve synchronization on small signals, including signals beyond the vertical amplifier’s nominal range. Trigger response only determines whether the sweep can synchronize; it does not restore attenuated or distorted vertical information or make this a 30 MHz measurement instrument. See the HM 307-4 sheet and manual scan.
What the component tester can—and cannot—tell you
The built-in tester applies an AC test signal and draws a voltage/current pattern on the CRT. The HM 307-4 sheet lists about 8.6 V RMS open-circuit test voltage, 28 mA RMS short-circuit current and 50 or 60 Hz test frequency. It is a quick comparative check, not a calibrated component analyzer.
- Useful for: comparing known-good and suspect resistors, capacitors, coils, diodes and transistor junctions; spotting broad open- or short-circuit differences; and quick qualitative semiconductor checks.
- Not a substitute for: accurate capacitance, ESR, transistor gain, leakage, breakdown-voltage or semiconductor-curve measurements.
- Interpret patterns cautiously: surrounding components and parallel paths can change an in-circuit result. Remove power from the equipment under test and discharge stored capacitors before connecting the tester.
A contemporary historical review characterized the tester as useful for indications rather than quantitative readings; see Electronic Servicing, April 1981. The test signal connects to the instrument’s ground/reference circuit, so observe the manual’s connection and safety instructions.
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Manuals and service documentation
- OPWeb HM 307-3 manual — combined user and service documentation, including operating instructions, tester use, maintenance, adjustment procedures, test plans and schematics.
- ManualsLib HM 307 scan — browser-readable manual scan with specifications and service material.
- eServiceInfo HM 307 and eServiceInfo HM 307-3 — alternate archival mirrors; confirm document identity and scan quality before relying on a procedure.
A forum reference to the former Hameg archive cites a PDF at cdn.rohde-schwarz.com/hameg-archive/HM307.pdf, but the reference alone does not establish that the file remains reachable or that it matches every suffix.
Service procedures involve hazardous CRT high voltage and mains circuitry. Do not open or work on a powered instrument unless you are trained and equipped for high-voltage servicing.
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Controls vary by revision, but expect intensity and focus; vertical position and volts-per-division; input coupling; timebase and fine adjustment; trigger source, slope, mode and level; and component-tester connections. Depending on version, there may also be X/Y or horizontal controls, an external trigger input and a calibrator output.
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Check the vertical variable-gain control before reading an amplitude. If it is out of its calibrated detent, the volts-per-division scale no longer gives a valid calibrated reading. Historical HM 307 coverage specifically flags this easy-to-miss error; see the December 1980 coverage.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.How to inspect a used HM 307
Check the case, CRT and accessories
- Look for cracks, deformation, corrosion, liquid damage, burn marks, missing knobs, damaged BNC sockets and damaged tester terminals.
- With the scope on, check that the trace is visible at ordinary intensity, focus is usable, and the trace can be positioned across the screen. Look for burn-in, a persistent bright line, weak brightness, or focus/astigmatism problems.
- Ask whether probes, tester leads, a suitable power cable and the correct manual are included. Probe voltage rating, compensation, connector fit and grounding all matter; a 10× probe can reduce circuit loading and extend the usable voltage range, but cannot increase scope bandwidth.
Ask for a meaningful powered demonstration
- Request a cold start and enough warm-up to see whether the trace remains stable.
- Check intensity, focus, horizontal and vertical position, and several timebase and volts-per-division settings.
- Apply a known low-frequency square wave or sine wave. Check vertical response at several settings, DC/AC/ground coupling, triggering and sweep operation.
- Test internal and external triggering where applicable, the calibrator output, and the component tester using known resistors, capacitors and diodes.
- Confirm the variable vertical-gain control is in its calibrated position before relying on displayed amplitude.
A single visual test does not establish bandwidth or calibration. A proper bandwidth check needs a calibrated source and suitable probe. If a seller says only that the unit “lights up,” that is not evidence of a stable trace or working measurement functions.
Review repairs, mains setup and shipping
Ask about replaced electrolytic capacitors, power-supply parts, CRT-related parts, vertical-amplifier transistors or FETs, switches, potentiometers, fuses and wiring. A disclosed repair is useful context, not proof of either good or poor condition. In one US marketplace listing, the seller reported replacing power-supply capacitors and the Y-input FET pair.
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Before connecting an imported scope, inspect the rear-panel voltage selector, fuse, plug and wiring. Never assume a European unit can be plugged directly into a US outlet. For shipment, ask how the CRT instrument will be packed; CRT neck damage, dislodged parts, broken panels and bent controls are risks. Local pickup or a functional return option is preferable when practical.
Used prices: interpret listings as signals, not a price guide
Observed 2026 marketplace signals are geographically and condition-specific. A US eBay example was listed at US$150 plus US$50 shipping and ended April 15, 2026; the seller disclosed the repairs above. German Kleinanzeigen results during May–July 2026 showed asking prices of roughly €40–€135. See the eBay listing and Kleinanzeigen results. These observations are not a stable market valuation or evidence that a listing is still available.
Condition, CRT strength, calibration, working trigger and component tester, probes, mains configuration, shipping, import charges and return rights can matter more than the model name. Do not treat the observed figures as a universal fair price, especially for an untested unit.
Is the HM 307 worth buying?
It can make sense for vintage and low-frequency service work
Consider a demonstrably working unit if you want a compact analog scope for audio, vintage radio, power-supply or basic low-frequency troubleshooting, value direct controls, and will use the built-in tester as a quick qualitative aid. Historical reviews described it as capable for portable consumer and industrial service work; the tester was valued for non-quantitative checks (Electronic Servicing, April 1981).
Choose something else for modern digital work
A modern digital scope is the better fit when you need multiple channels, waveform storage, single-shot capture, zoom and scrolling, automatic measurements, data logging, computer connectivity or serial-bus tools. A used dual-trace analog scope rated 20–100 MHz may offer more bandwidth and channels for similar money, but is usually larger and may be more difficult to repair. A dedicated component tester or curve tracer is a better tool for component-focused measurements.
Quick Recap
When to walk away
- The CRT is weak, burned in or cannot produce a controllable trace.
- The seller cannot demonstrate operation and there is no meaningful return option, particularly when shipping is costly.
- The mains selector or fuse configuration is unknown or unsuitable.
- The price assumes calibration or performance that has not been demonstrated.
- Your main work involves fast digital buses, single-shot events or measurements requiring documented calibration.
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon at the time of purchase will apply.
