The Emtech ZM-2 is a compact antenna tuner for QRP stations. It uses the popular Z-Match tuning system and is usable from 80 to the 10 meter band. The ZM-2 has a built-in resistive SWR reflected power bridge using an LED for indication of your match condition. It requires no batteries or power source for operation.
The specified maximum power rating is 15 watts, so it can't be used with QRO rigs. It has antenna output connectors for both balanced and coaxial type of transmission lines. You can order the kit from Emtech with either SO239 or BNC connectors. My unit has the SO239 connectors so I use a coax adapter for BNC cables.
Operation is easy, simply flip the tune/operate switch to tune position and adjust the two large knobs for minimum illumination of the reflected power light. If additional capacity is needed for some bands or load conditions, there are two additional fixed capacitors that may be switched into the circuit. Once the light goes out (or very dim), flip the switch back to operate and you're done.
It is best to keep the RF power low when using the SWR bridge, as you don't want to overheat the resistors in the bridge circuit. Once the match is found and the tune/operate switch is back in the operate position, it is safe to increase power, up the 15 watt maximum rating.
The ZM-2 and it's predecessor, the ZM-1, are ideal for QRP field operating, as they can match most any type of radiator. I have added the ZM-2 to my field kit and it goes with me anytime I head for the woods.
Emtech ZM-2 Links:
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Updated June 16, 2016