Tag Archives: Icom AH-705

Could the Icom AH-705 be used as a permanently-mounted remote ATU? Sure, but I believe there are better options.

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.

Since then, LDG introduced the RT100 remote antenna tuner.

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!

Icom publishes AH-705 antenna tuner details

Many thanks to Rob Sherwood (NC0B) who notes that Icom has published details regarding their new AH-705 antenna tuner which is designed to pair directly with the Icom IC-705 QRP transceiver.

Many Icom IC-705 owners have been waiting to learn more about the AH-705 before purchasing a dedicated portable ATU for their IC-705. Some of these details may help potential customers make a purchase decision.

Key specifications and features per Icom:

 

  • Covers the 1.8 MHz to 50 MHz bands

30 m, 98.4 ft or longer antenna: 1.8 – 54 MHz, 7 m, 23 ft or longer antenna: 3.5 – 54 MHz
* Depending on operating conditions or environments, the tuner may not be able to tune the antenna.

  • SO-239 antenna connector for 50 Ω antenna such as dipole or Yagi
  • “Terminal connector”, binding post socket adapter supplied for a long wire antenna

  • 2-way power sources using alkaline batteries (2 x AA cells) or external 13.8 V DC*
    * 13.8 V DC should be taken directly from an external power supply, not through the IC-705.
  • IP54 dust-protection and water resistance construction*
    * The connectors should be covered with an adhesive tape or a jack cover to prevent water seeping into the connection.
  • Full automatic tuning, just push the [TUNER] button on the IC-705
  • Latching relays used for saving power consumption
  • 190 × 105 × 40 mm; 7.5 × 4.1 × 1.6 in, 450 g; 15.8 oz* compact design
    * Battery cells are not included.
  • 45 tuner memories

Of course, I don’t have an AH-705 in hand to test yet, so there’s no way I can comment on performance.

Still, I can’t turn of the reviewer inside so I feel I can make some superficial comments assuming the specs don’t change.

Potential positives?

  • Complete integration with the IC-705
  • Could (potentially–?) be permanently mounted outdoors at the antenna feed point as a dedicated remote tuner
  • IP54 dust and water resistant
  • Power from internal batteries and an external DC source
  • It’s an Icom product, so I would expect excellent overall quality

Potential negatives?

  • Maximum wattage is only 10W, which I suppose is okay if you never put an amplifier between the IC-705 and the AH-705
  • Based on Icom specs, the AH-705 is larger than other portable ATUs at 7.5 × 4.1 × 1.6 inches. For example:
  • Some have noted pricing around $350 US price–that’s a premium for a portable ATU considering the Elecraft T1 is $180 assembled and many LDG models are less than $200. Of course, none of those ATUs have an IP54 rating, either.
  • Speculation here, but the AH-705 might only work with the IC-705 or Icom radios with similar ATU commands. One original pre-production prototype image of the AH-705 shows a power switch; the latest images do not. Like the mAT-705Plus, I’m not sure if the AH-705 can be turned on in order to tune only via RF sensing without essentially modifying a control cable to trick the ATU into powering up.

I was a little surprised to see that the AH-705 “only” has 45 tuner memories. In truth, I never really pay attention to this spec because I’m primarily a field operator. My radio sessions are only an hour or two long and I routinely pair my transceivers with a wide variety of antennas, so a portable ATU never has a chance to develop a complex tuner memory map for any given antenna. But as a reviewer, I try to step in other operators’ shoes so I see where this could be a slight negative for those who plan to use the AH-705 at home and connected to only one antenna. As a point of comparison, the mAT-705Plus has 16,000 tuner memories. Still, memories only help shave off a bit of the auto-tuning time. This would never have an impact on my purchase decision.

Biggest positive for me? IP54 rating

Since the AH-705 is designed to be dust and weather resistant,  it could be mounted at the antenna feed point. At home, perhaps it could act like an externally-mounted, remotely-controlled antenna tuner. I’m not sure what the maximum length of the control cable could be, but Icom Japan even lists a 16 foot control cable as an accessory. Of course, you would still need to follow Icom’s guidance about protecting the antenna, transmitter and control cable connection points.

Biggest negative for me? The size.

If the AH-705 specs are correct, it’s a little surprising Icom designed a portable ATU that’s this large. As you can see in the image above, it easily fits in the LC-192, but frankly since I’ve been an Elecraft T1 tuner user, I’ll notice that the AH-705 is 3.1″ longer, 1.6″ wider, and .7″ taller than the T1. It will certainly take up more backpack space.

Of course, unless I build an IC-705 control interface for the Elecraft T1, I can’t directly pair it with the IC-705 like I could with the AH-705. That said? I personally prefer pressing a tune button on the T1 and sending “QRL?” instead of hitting the PTT or CW key and allowing the IC-705 to kick in a continuous tune cycle for a few seconds. You might have noticed in some of my videos that when I tune to a new CW frequency, I’ll listen for activity, then tap the TUNE button on the T1 and send “QRL?” or “QRL de K4SWL”. By the time I’ve sent that string, the T1 has typically already found a match.

How will it perform?

I’ve got to assume the AH-705 will perform well. Icom tends to give their products thorough QC before shipping them to customers. I don’t anticipate any issues with the AH-705 as I did with the original maT-705, for example.

I’ll plan to test the AH-705 after it’s available.

For more information about the AH-705, check out the product page on Icom Japan’s website.