Featured: RigExpert AA-650ZOOM Antenna Analyzer at DX Engineering.
This is an affiliate link: Hood's Finds may earn a commission from DX Engineering at no extra cost to you. We have not tested this product; the specifics below come from the product listing.
An amplifier is more than its power devices. The low-pass filter on the output, the matching networks and the hand-wound coils all have to be right, and a meter cannot tell you whether they are. An antenna analyzer can help, because it measures impedance, SWR and reactance across a range of frequencies. The RigExpert AA-650ZOOM is one of the analyzers DX Engineering carries.
What the AA-650ZOOM offers
DX Engineering lists the AA-650ZOOM with a frequency range of 0.1-650 MHz and a Type N female RF connector. It runs on three AA batteries, 1.5 V alkaline or NiMH, and can take 5V USB external power. A case is included, and the analyzer weight is listed as 1.44 lbs.
Among its uses, the listing names measuring capacitance or inductance of reactive loads, cable testing and fault location, and tuning an antenna to resonance. ZOOM models allow you to zoom in on graph points for clearer analysis.
Using an analyzer on amplifier parts
- Check wound inductors. Measuring the reactance of a coil at a known frequency tells you its inductance, so you can adjust turns until a filter or tank coil matches the design.
- Sweep a low-pass filter. With the filter output terminated in a proper dummy load, the SWR at its input should stay low across the bands it is meant to pass. A sharp rise inside the passband points to a wrong part value or a wiring error.
- Test jumpers and feedline. Cable testing and fault location help find a bad jumper before it causes trouble at power.
- Check the antenna first. Knowing the antenna is resonant and well matched rules it out before you blame the amplifier.
Practical notes
Most HF amplifiers and radios use UHF connectors, so plan on a good-quality adapter for the Type N port and keep it in the analyzer case. Graphs are only as good as the connections, so use short, sound test leads.
An analyzer is a low-power instrument. Never connect it to a transmitter, an amplifier that could be keyed, or anything carrying RF. Disconnect the analyzer before any transmit testing.
What an analyzer cannot show
An analyzer measures at very low power. A filter or matching network that sweeps perfectly can still have a problem that only appears at full power, such as a capacitor running close to its voltage limit, a coil that heats up, or an arc across a tight spot in the wiring. Treat a good sweep as the first check, then confirm the finished amplifier with a careful power test into a dummy load while watching a wattmeter.
DX Engineering notes the charger comes with a European plug and requires a European to US AC adapter, sold separately, although the analyzer may be powered from a USB port. Li-Ion batteries are not supported, so stick with alkaline or NiMH cells.
And a reminder for any amplifier project: external linear amplifiers are not legal for use on CB radio. Careful measurement is part of building any legal amateur equipment well.
Where to get it
Check current price and availability: RigExpert AA-650ZOOM Antenna Analyzer at DX Engineering.
This is an affiliate link: Hood's Finds may earn a commission from DX Engineering at no extra cost to you. More picks on the gear page.
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