HF Projects

The Z-Match Tuner is back for a limited run. If you missed it the first time, now is your chance to build your own Z-Match Tuner (bail not included)

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The HFPacker Z-Match Tuner is a construction project with professionally crafted circuit board and case. It is reasonably simple to build and provides great utility in the shack or for HF Packing. This tuner design has been around for years and what sets it apart from other tuners is a resonant circuit which uses a fixed inductor.

Schematic

HFPacker Z-Match Tuner Features and Specifications

• Resonant tank circuit

• Band-pass filtering and harmonic attenuation.

• High Q and more efficient than other type antenna tuners.

• A fixed inductor simplifies construction and needs no rollers or taps.

• High Quality USA manufactured air variable capacitors. 600 Vrms.

• Clam Shell design provides easy circuit board access.

• Continuous Reflected and Forward Power Measurement.

• Light Bar Tuning. Ten LEDs in a bar graph of FWD or REFL outputs; On/Off

• BNC and SO-239 Input and Outputs. Eliminate need for adaptors.

• Bannana plug with ¾-inch spacing for balanced line output.

• 80-10 meter operation. Match balanced or unbalanced loads. 10-2000 ohms

• 100 Watt capacity

• Hi-Z and Lo-Z output selection

• Bypass or In-line operation

• Series Tuning with two additional capacitance selections

• Enclosure molded from flame retardant ABS plastic.

• Brushed Aluminum Front and Rear panels.

• 12V DC , 15 mA ; 75 mA during tune, On/Off switch. 2.5mm plug provided (internal battery provision).

• Size: 7.5 “ Deep by 6.25 “ Wide by 3.5 “ High (excluding bail)

• Weight: Less than 2 pound.

Theory of Operation

The Z-Match is well known for its ability to match a wide range of load impedances conditions over the HF spectrum. The HFPacker Z-Match Tuner is a single coil ZMatch.

“The input capacitor functions as the series arm of the L-network. The tank circuit formed by parallel capcitors and the inductor serve as the parallel or shunt arm of the network. A simple L-network of series capacacity and shunt inductance combined with an output coupling circuit. For fundamental reasons, an L-network of this type cannot match a resistance component loaded in parallel across its output that is lower in value than the desired reflected load (usually 50 ohms). In practice, this lowest value is even further increased because of limits in the adjustable range of the series capacitor. However, if the load resistance is applied to the output via a series reactance, the load resistance (now the series resistance component) is reflected across the L network output as a higher parallel value. Provided there is some series reactance, the L network can therefore match values of series resistance in the load lower than the norminal minimum value.” The HFPacker Z-Match output circuit makes use of this property and utilizes a selectable output link for matching low and high impeances. In adjusting the HFPacker Z-Match if you can get a match with both links, use the high impedance link. This loads the tank circuit more heavily, and may produce better efficiency depending upon the load that the tuner sees. If you are able to tune with the shunt capacitor at the higer capacitance end and lower capacitance end, use the lower capacitance solution for a better C/L ratio and better efficiency.

The input capacance is a dual section air variable capacitor with the second section switched in and out (ADD 1) A fixed capacitance may also be switched in parallel with the input capacitance (ADD 2). The tank circuit capacitance consists of a dual section air variable capacitor. The top of one capacitor connects to the top of the inductor. The top of the other section conects to the center tap of the inductor. The bottom of both sections connect to the bottom of the inductor.The frames of both air variable capacitor are insulated from ground. Phenolic shaft couplers are used to isolate the capacitors from the user. A rear panel switch selects the high impedance or low impedance link. A rear panel switch grounds the low side of the output link for unbalanced coax connections.