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Diehl Martin
PO Box 1192
Guntersville, Alabama
35976-7992
USA
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Projects:
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Installing the HexBeam  
Building a Go-Kit
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LDG Z-11 Pro
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Review of LDG Z-11 Pro Antenna Tuner

exterior of z-11 pro tuner
Figure 1. External view of the LDG Electronics Z-11 Pro Tuner

Fast, Accurate, and it Learns Too!

For various reasons, Monica (N6PSD) and I have moved a lot from place to place, and under various circumstances, have had to use many seemingly random antennas for our amateur radio pursuits. So, for more than thirty years, we have built or bought various “antenna tuners” in order to match the impedance of the antenna and feedline to the 50 ohm output impedance of the transmitters. The first one we bought in 1973 was a Johnson Matchbox Jr., which was a beautifully built unit meant to drive balanced loads – for instance dipoles fed with open wire line. The first one we built, also in 1973, was an “L-match” using an E. F.  Johnson roller inductor and variable capacitor, which was excellent for matching end-fed long-wire antennas. There have been many since, and each has had its strengths and limitations.

Each of those older antenna tuners was manually operated. Each required manually determining the settings with the best “match” and retuning whenever the frequency or band was changed. During 2002 we bought an automatic antenna tuner for our portable station, based on a 5-watt Yaesu FT-817. The tuner for that was an LDG Electronics Z-11, and it was remarkable. Given a transmitted carrier, the Z-11 would match virtually any load we gave it, and do so within a few seconds. It was a great setup, but because the Z-11 could handle no more than 50 watts, we could not use it on the “big rig” which put out 100 watts. Then in 2006 LGD Electronics announced their new and improved model, the Z-11 Pro, which has several greatly improved features, among which is being able to handle transmitters up to 125 watts output. We bought one of the new Z-11 Pro antenna tuners, and it is a treat.

interior of z-11 pro tuner
Figure 2. Internal view. Note the many relays used to change the L and C values. The 68CH11 microcontroller is in the bottom right hand of the circuit board.

Features

Small - The LDG Electronics Z-11 Pro is small enough to be appropriate with the FT-857D Ultra-Compact Transceiver. The tuner is tiny and will sit under or on top of the FT-857D, providing a very compact portable station capable of driving most any antenna, at the 100 watt level.

Loads up most anything - The LDG Electronics Z-11 Pro provides a wide impedance match throughout the 80 through 6 meter bands. There are loads it will not match, but for typical ham antennas, it does very well. For instance, I have no trouble loading the 80 meter dipole on 6 meters, or the 10-12-15-17-20 meter HexBeam on 30 meters. It will successfully match some antennas on 160 meters, but 160 meters is at the limit of its range.

8000 Memories - The LDG Electronics Z-11 Pro learns as it goes along. It remembers successful matches and correlates the frequency with the match, so that if you return to a frequency near one you have been on before, it will first try known successful tuning combinations rather than starting over from scratch tuning each time. In the majority of cases, for me, changing bands or frequencies results in a tuning cycle of a half second or less. Once the tuner has been “trained” with a particular set of antennas, it can be set to automatically tune on the fly. This is very impressive in action.

Nicely Made - The LDG Electronics Z-11 Pro is very nicely built. The pushbuttons are much nicer then the switches used on the original Z-11 tuner. The metal case looks good, and provides a good deal of shielding.

Things to Watch Our For:

RFI Problem - My particular unit has RF susceptibility issues. If I transmit on 446 MHz (not using the feedline through the tuner), the tuner lights blink and it gets confused. Putting a ferrite choke on the power line into the tuner solves the problem.

No power switch – it is all automatic. The power consumption is very low on standby, and that might not seem to be an issue, but the only way to turn it all the way off is to disconnect its power cord.

Read the Manual -  There is a lot more functionality in this unit that initially meets the eye. It would be a good idea to read the manual all the way through at least once, in order to learn how to make the tuner do what you need it to do.


I like the LDG Electronics Z-11 Pro tuner. It does exactly what I want it to do, and does it well. It is also cost-effective. After using this tuner for a while, I find that, more and more, I wish that my MFJ-989C tuner were this user-friendly.


73

Diehl Martin
W4TI
October 2006


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