You can build a working station with no test gear at all, and diagnose almost nothing. A short list of inexpensive instruments turns guesswork into measurement.
Buy first
- Digital multimeter. Any $30 meter with continuity, DC volts and resistance. Most station faults
- Vector network analyzer. A NanoVNA-class analyzer costs less than a length of good coax and
- Dummy load. Lets you test, tune and measure without radiating. A 100 W load is enough for
- Directional wattmeter. A meter that reads forward and reflected power separately, so you know
are a bad connection, and continuity finds them.
measures SWR and impedance across a whole band, so you can see whether an antenna is short, long or simply not resonant where you thought. It also measures cable loss and finds the length of an unknown coax run.
anything short of an amplifier.
whether a high SWR reading is the antenna or the meter. Cross-needle types show both at once.
Buy later
- Antenna analyzer with a built-in display if you prefer to work up a tower without a laptop.
- Oscilloscope. A cheap digital scope is for audio, interfacing and power supply ripple, not RF —
- RF current clamp. Shows common-mode current flowing on the outside of your coax, which is the
- Signal generator and step attenuator. For receiver comparisons and direction-finding
- Power supply with current limiting for bench work, so a wiring mistake blows nothing.
useful for building and repairing, unnecessary for operating.
real cause of most "RF in the shack" and computer-interference complaints.
practice.
Common measurements
- Is my antenna resonant? Sweep SWR across the band with the VNA. The dip tells you the resonant
- Is my coax bad? Terminate the far end in a dummy load and measure loss. Compare with the
- Is that noise mine? Kill the house breakers one at a time while listening. Half of all "band
- Is the radio putting out? Into a dummy load, measure power on each band. A single dead band
frequency; an antenna too long dips low, too short dips high.
manufacturer's figure for that length and frequency; more than about 1 dB extra usually means water ingress or a failed connector.
noise" is inside the building.
usually means a relay or filter, not a final.
Borrow rather than buy
Clubs are a better source of test equipment than a credit card. Spectrum analyzers, service monitors, tower-mounted analyzers and calibrated loads are exactly the things a club should own and members should share; a "test equipment night" is also one of the better meeting programs going. See starting a club and club resources.