I received the new LDG Electronics Z-100 Automatic Antenna Tuner today and have put it through an initial workout. In some ways the Z-100 is a replacement for the old reliable LDG Z-11 tuner that QRP operators enjoy while adding some new capabilities that should make this tuner a prime choice for QRO operators as well. In the following paragraphs, my first-look impressions as presented. Oh yes, I guess it might be interesting to first point out that the retired Z-11 price was $179 while the new Z-100 price is only $149 (assembled and tested). There is NO kit version of the Z-100.
First, the Z-100 case shape is different than previous LDG tuners and actually looks very nice when you see it in person. The photos don't do it justice. What is immediately apparent is the Z-100s' small size (5.5" x 5.5" x 1.5"). This is 3" shorter than the Z-11 and just 1/4" thicker. In addition, it weighs only 14 oz (1 oz less than the Z-11). Impressive.
While the Z-11 power limitation is 60 W PEP (30 W CW), the Z-100 can handle 125 W PEP (100 W CW) and covers 6-160 m (50 W on 6 m). The SWR range is still the 101 (31 on 6 m) that is typical of LDG tuners (6-800 Ohms). Remember that neither the Z-11 or the AT-11MP were intended to be used on 6 m.
The Z-100 has latching relays to hold the tune even when the power is off. The input voltage range has been extended to 7-18 VDC! Okay, don't get over excited and think you can power the Z-100 from your FT-817 ... the FT-817 can not provide the 300 mA needed by the Z-100 during tune. But a single 9 VDC cell can do a credible job! Alternatively, the FT-100D, FT-847, FT-857, and FT-897 can power the Z-100. Other radios may or may not have the capability.
The Z-100 uses a microprocessor controlled, switched L tuning network. Unlike the Z-11, RT-11 or AT-11MP, the Z-100 has 200 tune memories. So what are these tune memories all about? This may be the slickest innovation from LDG in a while. Every time you command the Z-100 to perform a full tune, and it accomplishes the match, the L and C values are stored in the memory using a FIFO architecture. More on this in a moment after I explain how the Z-100 differs from the other LDG tuners in user interface.
Try as you may, you will not find a power switch on the Z-100. When not tuning, the Z-100 is in a "deep sleep" state that requires < one microamp. This current is so small, that one can consider the tuner to be off. The front panel has a single push button and two LEDs, one red and the other green.
In operation, you have three modes from which to select. The first mode is the Bypass Mode, which is activated by giving the tune button a quick press (< 500 ms). This mode should be used when the antenna's SWR is < 1.5:1 in order to maximize system performance. The second mode is the normal tuning cycle where the full-search tuning algorithm is used. This can take a few seconds to complete. This mode is activated by holding the tune button for 3 seconds. The memory mode is activated by holding the tune button for more than 0.5 second and less than 3 seconds. Along with the button pressing, the LEDs indicate what mode is being activated and an indication of the SWR. This is covered in the manual. I note that a steady green LED indicates a SWR < 15:1 while a flashing green LED indicates a SWR of 1.5:1 to 2:1. If it is off, the SWR is > 2:1. The LEDs are illuminated only during the tuning process.
I tested the unit I received using a FT-817 and a FT-857. To make tuning easier, I used the W4RT One-Touch Tune module (OTT-897) with the Z-100. Yes, the Z-100 is fully compatible with the OTT-817 and the OTT-897 (which works with the 817and 857 too). My test antenna was a 5-band Hex-Beam (10-20 m) that has low SWR on the 10-20 m bands and really bad SWR on 30, 40, and 80 m. I first used the FT-857 with the Z-100 with the power output of the 857 set to 100 W. The Z-100 easily and rapidly tuned to the Hex-Beam on 10-20 m. Then 30 m was tried and the tuning went well, taking about 3-4 seconds. Same for 40 m. When I tried 80 m, the Z-100 chattered away for about 5-6 seconds and also found a good match. I note that not all of the tuners I have can perform this feat. My impression of the full-search algorithm performance compared to the performance of the other LDG tuners I have is that the Z-100 appears to work at least as well as the AT-11MP (my favorite to match anything) if not better. When I used the FT-817 set for 500 mW, the Z-100 tuned just as well as it did with the FT-857 set at 100 W. The Z-100 was "happy" with the low-power input. The Z-100 specifications state that it can tune with as little as 100 mW input. Oh yes, the foldback worked well in the FT-857 and the Z-100 algorithm accommodated this well and found nice matches in every case.
Now to the cool part ... the memory tuning. As mentioned above, the Z-100 stores the L and C values for each successful tune, but not the frequency since it doesn't sense the frequency of the carrier. These data are stored such that the first data stored are the first data dumped out of the memory once it fills, i.e., the classical FIFO method. Two-hundred tunes can be maintained in the non-volatile memory. When you activate the memory tune mode, the tuner begins checking the SWR using the most recent tune data stored, then the next most recent data, and so on until it finds data that produces a match with an SWR < 1.5:1; however, if it doesn't find an acceptable match, the turner activates the full-search algorithm to find an acceptable match. Of course, the data for the full-search mode are stored in the tune memory. This memory-search technique results in blazingly fast matching!
After I used the full-search mode to cover most of the 10-80 m bands while matching to the Hex-Beam, I then used the memory tune mode to hop between bands. The first time or two, I literally didn't think the Z-100 was working because all I saw was a brief flash of the LEDs and heard what sounded like a relay latching. When I looked at the SWR on the radio, it was zero or one bar. Flipping between 15 m and 80 m, and then back again, in the normal tuning mode takes about 12-15 seconds. When the memory tune mode, it took more time to change bands on the radio than for the tuning! I am impressed so far with this new feature. The memory-tune mode is a real plus when operating in the field QRP with limited power since the Z-100 really conserve power by the near snap tuning and deep sleep standby mode.
Just for fun, after I stored some tuning data using the FT-857, I switched to the FT-817. When I used the memory tune mode, the match remained the same as one would hope. With 200 memories, it is not unreasonable to think that you can tune to several of your antennas and store the data so that you will not have to restore data each time you change antennas. But if something doesn't match, it is easy enough to use the full-search mode.
LDG has developed its own One-Tunch Tune devices for the various radio, viz., ICOM, Kenwood, Alinco, and Yeasu. They also have interface cables. For the Yaesu radios, the LDG OTT does not provide a CAT port feedthough. For this feature, you should use the W4RT OTT-897 or OTT-100D as appropriate.
My Z-11 has been a valued "friend" for some years as have my AT-11MP and RT-11, but I rather think that this small, but mighty, Z-100 autotuner will become my do-all tuner for both QRP and QRO.
72/73,
Barry - W4WB
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