You’ve no doubt heard me brag about the Emtech ZM-2 ATU in previous field reports. I think it’s an accessory every field operator should have.
The ZM-2 is a very capable manual transmatch/ATU and is also one of the more affordable tuners on the market. It’s available as both a kit and a fully-assembled unit. Both well under $100.
I do believe the “manual” part of the ZM-2 scares off some and it really shouldn’t. We are used to simply pressing a button these days and allowing our automatic ATUs to do all of the matching work for us.
Manual ATUs do require some amount of skill, but truth is, the learning curve is very modest and intuitive.
Manual ATUs require no power source in order to operate–you adjust the L and C values by hand–thus there’s never a worry about the ATU’s battery being depleted. They also are easy to manipulate outside the ham bands because they require no RF in order to read the SWR–you simply make adjustments to the L and C until you hear the noise peak. This is why many shortwave broadcast listeners love the ZM-2 so much. It’ll match most any antenna you hook up to it!
I also argue that everyone should have a portable ATU even if you operate resonant antennas. Think of an ATU as a First Aid Kit for your antenna: if the deployment is less than ideal, or if you damage it in the field, an ATU can help you find an impedance match your radio can live with. ATUs have saved several of my activations.
Mountain Topper MTR-4B V2
I’ve also mentioned that I’ve had an MTR-4B on loan from a very kind and generous reader for most of the year. He was in no particular hurry for me to send it back to him, but I wrote him in early November and said, “I’m doing one more activation with this little rig, then I’m shipping it to its rightful owner!”
He had a request, and it was a good one:
I think it would be a good little twist to the usual YouTube if you paired a random wire with the ZM-2 and the MTR-4B…showing how to tune the ZM-2 with a Mountain Topper…
I really liked this idea, so I made plans to to hit the Blue Ridge Parkway nearby and give it a go.
The first time I tried this in the field, I paired the MTR-4B with one of my Sony amplified speakers because the MTR-4B 1.) has no internal speaker and 2.) has no volume control. During the video, however, I realized that there simply wasn’t enough audio amplification so that the viewer would be able to hear a noise peak as I manually tuned the ATU. I decided to scratch that video and just do the activation on my own. I really wanted to show how the tuning process worked in the video.
Many thanks to Joshua (KO4AWH) who shares the following update to his previous guest review of the ATU-10 automatic antenna tuner:
Update on the ATU-10: new firmware released
by Joshua (KO4AWH)
The short story is that David N7DDC has a Firmware update with a new tuning algorithm that seems to fix the previously seen failure to find a decent match. As noted earlier in comparison with the Elecraft T1, the ATU-10 still does not necessarily get as close a match to 1:1 SWR but it now does indeed find a good match making this tuner my go to for use with my IC-705.
Not previously mentioned, the ATU-10 is also designed to work with the IC-705 for tuning commands when connected with a TRS 3.5mm cable, not just as an auto tuner when given a signal. And, in practice it works just as it should. I actually took the IC-705 and the ATU-10 and worked a SOTA/POTA with the beta version of this new firmware. I ran a 35’ wire and it worked great allowing me to work 40m, 20m, 15m and 6m for a total of 26 contacts. As a followup to my previous testing with the prior firmware 1.4, below are my results with the current new 1.5 firmware.
Testing on August 20th, 2022
The only difference from the original testing is the 31.5’ radiator was replaced with a 35’ and I did not tune and record results with the T1.
Conclusion on the ATU-10
I now feel very comfortable recommending this ATU. newdiytech.com has a great price and the build quality seems just fine. With the new algorithm update, a good match is found. The ATU-10 works great stand alone and also works fully automatically when used with a IC-705. This configuration means you can put the ATU at the antenna feed point and run a control cable back to the IC-705 and have a 50 ohm across the coax to help minimize loss, making for a nice portable setup with great band hopping flexibility.
If your curiosity is strong, here is some testing I did for David as he was updating the Algorithm now used in firmware 1.5.
UPDATE August 3rd 2022:
David Fainitski N7DDC has released a test firmware with a new tuning Algorithm with some promising initial results. A quick test on each band in the table has been added to reflect the new algorithm. This is not a firmware update yet but I suspect it will be soon. Results are great as tested. I hope to see this in a new FW soon.
August 6th, 2022
A second test firmware from David Fainitski N7DDC with the ability to increase or decrease the L and C manually allowed me to verify if a better match could be made. Turns out in a few cases it could. After testing again with a Tufteln 9:1 T80-2X2 on a 41ft sloping radiator I was able to achieve much better results than with the current version 1.4. In two cases I was able to find a better match manually. I realized later that if I were to tune a second time the ATU-10 would find the same, better match, on its own. Again, not a full firmware update, i.e. you have to flash back to 1.4 if you want to be able to turn off the turner.
(Click to enlarge.)
August 7th, 2022
Another test firmware David asked me to check. This version seemed more likely to find the best match. I did have the ATU go to L0, C0 twice but then find a match on a second try. This happened once on 40m and once on 10m. Almost like it faulted but there was some switching/clicking involved before stopping, it just landed at a 3:1 or higher with 0 for L and C. A second tune however straightened it out. I did not record those two cases. Below are the results. I was able to find a slightly better match twice but I am sure one would never notice the difference during normal use. The improvement both times was within the error of SWR across the three device measurements.
Many thanks to Joshua (KO4AWH) who shares the following guest post:
UPDATE: Please check out Joshua’s most recent review after updating the ATU-10 with new firmware. The results have improved dramatically.
ATU-10 Random Wire Testing
by Joshua (KO4AWH)
I had a bit of time to do some field tests and I recently acquired an ATU-10. So I jumped right in and did some ATU-10 Random Wire Testing. The testing was completed with a Tufteln 9:1 QRP Antenna configured with an elevated feed point sloper and a counterpoise hanging straight down. The coax feed was RG316 17′ with the ATU at the radio with a short jumper. Several different radiator lengths are used as mentioned below. The ATU-10 was sourced from newdiytech.com, price was $120.24 shipped to me in GA USA, Ordered June 25, delivered July 8th.
A quick list of ATU-10 Features:
0.91″ OLED Display that shows Power, SWR and internal battery remaining.
USB-C Rechargeable LiPo 1.7Ah
Grounding Lug
Bypass Mode (When I set to this mode however it would tune anyways)
Latching Relays (No power needed to keep in position. Hold tune with ATU off)
Input port for communication with IC705 (and potentially others)
7 Inductors, 7 capacitors
(Elecraft QRP)
C array, pF 10, 20, 39, 82, 160, 330, 660
L array, uH 0.05, 0.11, 0.22, 0.45, 0.95, 1.9, 3.8
ATU-10
C array, pF 22, 47, 100, 220, 470, 1000, 2220
L array, uH 0.1, 0.22, 0.45, 1.0, 2.2, 4.5, 10.0
USB-C firmware update (ATU shows up as a drive, simply copy the new firmware file to the device and it will automatically update)
Weight 232g (8.1oz)
Tufteln Case adds 23g (.8oz) for a Total of 255g (8.9oz)
Compared to the T1 with cover for a total weight of 187g (6.5oz)
SWR measured with a RigExpert RigStick 320, Lab599 Discovery TX-500 and the ATU-10
The test process was to first check the SWR on the antenna with no tuner. SWR values recorded from the TX500 and RigExpert Stick 320. Values recorded in the 2 columns under the “No Tuner” section. This was completed for each of the Bands listed in the table rows (see below). SWR values were the lowest in the band range for all recorded numbers. Continue reading Joshua tests the ATU-10 portable automatic antenna tuner→
Icom uses this photo to demonstrate one of the ways the AH-705 ATU can be mounted for remote operation.
Many thanks to Bruce (W0MBT) who writes:
Hey Thomas,
After many years of inactivity, the combo of this blog, the IC-705, and Covid shutting down all the other fun things I like to do has finally got me somewhat active again. I agree with you that [the Icom AH-705] seems pretty large and expensive for a portable tuner, given the available alternatives. To me, the most interesting possible application is in a semi-permanent outdoor installation.
Currently, my setup is an EmTech ZM-2 installed in a watertight toolbox on my fifth floor balcony, grounded into the metal siding of my building, with a stealth radiating wire tossed onto a conveniently-located tree. It seems to get out pretty well, but QSYing across bands is a pain, and not really practical when it’s raining, which happens a lot in Seattle. I could replace that whole setup with an AH-705 stuck to the siding with double-sided tape.
My questions (and I realize you won’t yet have answers) are:
* How long will it run on AAs? This will determine whether I need to run 12V out to my balcony.
* What’s the maximum control cable run? In my current apartment layout, I’m looking at about 25′.
Bruce
W0MBT
Hi, Bruce,
First of all, I’m so glad to hear you’ve gotten back on the air and honored to hear this blog might have contributed to that a bit! Based on your current setup, it’s obvious that you’ll go out of your way to play radio. Anyone who’s willing to manually adjust a remote ATU each time they wish to hop around the band is dedicated to their radio play!
Since the AH-705 hasn’t been released yet at time of posting, I really know nothing about the AH-705 other than what I’ve read in the specs. I’m not sure how long a control cable could be nor how long AA batteries would last. We won’t know this until the AH-705 is tested.
If I were in your shoes, though, I wouldn’t wait on the AH-705.
I can think of at least two other options I consider to be better choices for a permanently-mounted remote antenna tuners:
1.) Assemble a remote tuner box
So at my QTH, like yours, I rely on an external, remotely controlled ATU. My shack is located on the first floor of my house. There’s a carport with a metal roof behind my shack. Since we designed and built this house. we installed conduit in the walls so that I could run cable from my shack to an antenna switching and tuning point mounted outside.
It’s built around an LDG Z11 Pro which is not marketed as a remote ATU. The Z11 Pro is mounted in a (rather ugly but effective) weather-proof box a friend gave me–I think the box was originally used in a remote sensing application. It actually has some penetration points on the side I was able to use.
In 2011, when I installed this ATU, I found an old sealed lead acid battery to power the Z11 Pro knowing the Z11 actually requires very little in terms of power. I had planned to bring the battery indoors and occasionally recharge it, but I also happened to have a 5 watt solar panel and Micro M+ charge controller, so I put them to use charging the remote ATU battery.
From inside my shack, I bypass all internal ATUs in my transceivers and only use my remote Z11 Pro.
The Z11 Pro is RF-Sensing, so as I move across the band, it automatically finds matches and keeps the SWR well within an acceptable range (I monitor it indoors with an SWR and Power meter, of course).
This entire system costs less than the $350 projected cost of the AH-705 and doesn’t require a control cable. The best part is it can be used with *any* radio and can handle 125 watts.
I used the Z11 Pro because I already owned it, but there are less expensive, smaller LDG tuners that could be used. You wouldn’t need to have solar charging as you could simply replace an external battery from time to time. These tuners are super efficient–so efficient, the sealed lead acid battery I installed in 2011 was nearly dead back then, yet it has provided enough voltage via my small PV panel to reliably power the Z11 Pro over 10 years of seasonal temperature swings.
But there’s still an easier and possibly cheaper solution.
2.) Buy a proper remote ATU
When I originally built my remote tuning system, there were really no affordable options commercially available. I believe SGC and Icom had remote tuners but they were very pricey.
The RT100 costs $250 US and is designed to be used outdoors permanently-mounted. You need no outdoor power source because the ATU is powered from a Bias T 12V source via the same coax cable between your transceiver and the ATU. Makes for a neat, tidy package outdoors.
Again, this ATU–unlike the AH-705–can handle up to 125 watts and work with any transceiver in your shack.
Indeed, I’ve been thinking about grabbing an RT100 for use with another outdoor antenna I plan to build!
Also check out the MFJ-926B for $330 US. If you’re like me, you may never operate north of 10-20 watts, but some may appreciate the 200 watt power handling of the MFJ.
Summary
To get back to your original question, I suppose what I’m trying to say here is the Icom AH-705 is a portable antenna tuner that can be put into service as a remote antenna tuner. It can do both jobs.
To me, though, it makes more sense to split these two applications: install a permanent remote ATU–that works with any transceiver–and also invest in a quality portable ATU for field work.
What are the major drawbacks of the AH-705 compared with a proper, dedicated remote ATU?
You’ll need to change AA batteries in the AH-705 on occasion or design a 12V source that can easily be recharged.
The AH-705 may (we don’t know yet) only work with the IC-705 and possibly similar Icom models. The LDG and MFJ ATU models above work with any radio.
The maximum power handling of the AH-705 is 10 watts–if you use other transceivers (if that is even possible) you’ll have to be extremely careful of your power settings, else fry the AH-705.
The AH-705 is pricey if the actual retail price ends up being near the projected $350 mark. Hopefully, it’ll be less than this.
The AH-705 will require a control cable. The options above are RF-sensing and do not.
My advice?
Build or buy a permanent remote tuner and hit the parks and summits with the ZM-2!
Since you already have the Emtech ZM-2, you’ve got a fabulous manual portable ATU. I use my ZM-2 in the field all the time (see photo above). Some folks prefer an automatic tuner for ease of use, but I’m guessing at this point, you’re an expert ZM-2 “tuner upper!”
Later, if you want to add an automatic portable ATU to your field kit, consider the Elecraft T1, the Icom AH-705, or an LDG model.
Readers, feel free to comment with your suggestions as well. I’m sure there are a number of options I haven’t considered!
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You’ve no doubt heard me brag about the Emtech ZM-2 ATU in previous field reports. I think it’s an accessory every field operator should have.
I’ve also mentioned that I’ve had an MTR-4B on loan from a very kind and generous reader for most of the year. He was in no particular hurry for me to send it back to him, but I wrote him in early November and said, “I’m doing one more activation with this little rig, then I’m shipping it to its rightful owner!”
