The Z

The Z-11 Pro Antenna Tuner GM1SXX Feb 2006

Although described by the makers as an automatic antenna tuner, we all know better, dont we? In reality, this item should more properly be described as an 'automatic impedance matcher' or an AMU 'antenna matching unit' since that is its actual purpose. ATU's don't normally 'tune' antennas, they merely present an acceptable match to your transceiver.

The Z-11 Pro is a small, portable antenna impedance matcher designed for battery operation. In size it is only 5" x 7.7" x 1.5", and weighs around 1.5 pounds. It's designed to handle 0.1 to 125 watts, making it ideal for both QRP use and with standard 100 watt transceivers from 160 - 6 meters.

The matcher uses a 20Mhz PIC processor (PIC16F876) driving a (now obsolete) UCN5818EPF fluorescent display driver IC to provide a multitude of output control lines to drive the relays and LED's. These output lines control the settings on an L-match network. The L match is constructed from seven toroids and nine dipped-mica capacitors. A modified Breune type SWR sensor monitors the SWR as seen by the transceiver and provides feedback data to the PIC microcontroller which selects the best L/C combination via a bank of latching relays when you key the rig or enter a tuning cycle from the front panel.. The memory chip used is an 25C256K type. I'm not familiar with that part number but I'd guess it is an EEPROM.

The Z-11 Pro will match dipoles, verticals, inverted-Vs or virtually any coax-fed antenna. It was designed to drive relatively low impedance antennas. Of course with an outboard 4:1 balun transformer, it will also match long-wires or antennas fed with ladder-line.

The unit has 8,000 memories and automatically stores matching configurations for each frequency and band as you use them, for each of four antennas on the single RF port. If you transmit on or near a frequency you’ve used before, the Z-11Pro re-matches from memory almost instantly. Otherwise, it enters a tuning cycle to find the best match. This cycle takes around five seconds.

To store an L/C setting in memory you have to key the rig, hold in the 'tune' button for about 3 seconds until the two centre LEDS are lit then let go of the tune button while keeping the rig keyed. The unit then seeks for and stores the best match. Each frequency takes around 10 seconds to match and store.

There are two tuning modes.... Automatic and semi-Automatic. A bypass mode is also provided.

The manual is badly written and presented. It could be a LOT better. It's a model of muddle.

Optional interfaces are also available at extra cost for most Icom, Kenwood, Yaesu and Alinco transceivers. When using the interface, a single button-press transmits a carrier, executes a tuning cycle and returns the radio to its original power and mode.

Front panel LEDs indicate the operating SWR and status. The Z-11Pro uses latching relays which retain the tuned configuration even when powered down making it ideal for QRP use. The current draw when not tuning is extremely low since the PIC is then in 'sleep' mode.

This is a very versatile matcher, ideal for both base station use (with a conventional 100W transceiver) or for field use with your QRP radio. maximum safe input power is 125 watts.

Although this unit could be operated from internal batteries, no battery holder is provided although there are a couple of PCB pads provided to connect such a battery to. Should you want to do that, ALKALINE types are recommended. The unit takes a fair current when active. The PCB connection pads for the battery are tiny. Take care when soldering to them. Eight ALKALINE batteries use normal for running this tuner in the field. The batteries would need to be fitted in a suitable holder glued to the underside of the cabinet lid.

A DC power lead is supplied with the unit to power it from a 13.8V station supply.

Construction quality is good with plated-through double sided PCB with silk-screened overlay and good quality components. Its light in weight and the latching relays and EEPROM memories make it fast and versatile in use. Until now, I have always relied on my own DIY tuners, mostly L-matches and although they work very well, it takes time to tune them. BORING! This tuner, once you have taught it the characteristics of your antennas tunes almost instantly. Just a blip of the PTT and voila... matched.

The manufacturer's specifications are listed below.

0.1 to 125 watt power range (SSB and CW), 100W on 6M.
8000 memories for instantaneous band changing.
Tuning time: 0.1 to 6 seconds full tune, 0.1 seconds memory tune.
Selectable user parameters: Auto/Semi, threshold, and more.
1.8 to 54.0 MHz coverage. Built-in frequency sensor.
Tunes 6 to 1000 ohm loads (16 to 150 on 6M), 6 to 4000 ohms with optional 4:1 Balun.
For Dipoles, Verticals, Vs, Beams or and Coax Fed Antenna.
Optional external 4:1 Balun allows tuning of random length, long wire or ladder line fed antennas.
Optional interfaces for Icom, Alinco, Kenwood and Yaesu available.
Power requirements: 7 to 16 volts DC at 300 mA Max. 25 uA standby current.
User installable 6 or 8 x AA or AAA holder lasts over 2 years.
Small Size Enclosure: 7.7” x 5.0” x 1.5”. Weight: 1.5 pounds

For anyone interested, there are some reviews of this 'tuner' at http://www.eham.net/reviews/detail/5388

I agree with one reviewer on eham.net who suggested that the manual was rather confusing. IMHO it could be more clearly written. Perhaps including a simple 'crib card' containing the most used options, keystrokes and LED display settings would be useful.

In general, I like this AMU a lot. Life is short and fiddling with AMU's doesn't do it for me any more.

This is the Z-11 Pro with the cover removed. You can clearly see the relays and the red coloured toroids. The mica capacitor are placed between the two banks of relays while the large square chip is the fluorescent display driver chip. The PIC is the chip with the label attached.

The SWR sensor is in the top right hand side above the line of red toroids. It is a single turn of wire fed through a miniature toroid.

Although not fitted with one, there is space to fit a battery carrier to take up to six AA size alkaline cells for tuning on the move.

The unit comes with a matching power lead for an external power supply.

In the above photo you can see the Z-11Pro sitting on top of my smallest home-made L-Match.

Which would you rather take out into the countryside?

No Contest!

Behind the tuners are my much loved Yaesu 'Twins', the FR-101s and FL-101 1970's 'Boat Anchors'. On top is my renovated IC-730 ,and station clock, a wind up chronometer from a scrapped MIG fighter aircraft.

73 Al.

GM1SXX