A long, long time ago (everything seems to be a long time ago these days) Icom announced the AH-705 Automatic Antenna Tuner for the excellent new IC-705 and on Friday 19th March 2020 Icom UK sent out a press release that it was now available to buy here in the UK. I got my order in to Nevada Radio as soon as I could and waited.
It arrived on the 23rd, less than 24 hours after being dispatched – well done Nevada Radio and Parcel Force.
So enough of the pre-amble you all want to know more about it I’m sure, as I don’t do reviews this is not a review of the AH-705 but its a little more info about it and my first thoughts.
What does it do?
You can see the Icom brochure here – https://icomuk.co.uk/files/icom/PDF/newsFile/AH-705-brochure.pdf but basically it will tune a long wire to 1.8mhz to 50Mhz with a 30m or longer wire, or 3.5Mhz to 50Mhz with a 7m or longer wire. but that’s not all it will also allow you to attach a standard pl259 and tune your coax fed antenna which means its as versatile as it could be. I suspect that its best suited to a long wire antenna because as we all know the best place for a tuner is at the end of the antenna not the end of the feeder line from the antenna, but I intend testing it with as many options that I can find, including some things that maybe wont work very well like barbed wire fences and things 🙂
What’s in the Box?
Opening the box we find the instruction leaflet – not sure what that’s for 😉 – the the AH-705 tuner, control cable, coax terminated in BNC connectors, a small bracket to attach a strap to for mounting the tuner to a pole, a terminal post adapter for long wire and a power plug so you can make up a 12volt power cable.
Power for the AH-705 is provided by 2xAA batteries. These are fitted easily by removing the flap on the back of the tuner. There is also the option making a cable to connect to your 12volt radio battery (the plug is supplied) but as my soldering skills leave a lot to be desired and I want to keep the number of cables to a minimum I will probably stick to using the batteries.
As you can see from the power connector picture above, on the bottom we have the BNC connector for the feeder to the IC-705, control cable connector and the 13.8 volt power socket. Its worth noting that the supplied Coax feeder and control cable are the same length so its good to see that someone was thinking logically about how this works 🙂
On the top we have a standard SO239 connector and a terminal for the ground. Ground can either be some wire radials/counterpoise or a connection to a ground spike.
Connecting to the radio and control
Connecting to the radio is simple enough, after connecting a suitable wire or antenna to the AH-705 connect coax feeder to the AH-705 and to the radio Antenna BNC and connect the control cable to both.
Open the FUNCTION screen, navigate to the second screen and touch the TUNER option to tune it on. this will cause the AH705 to tune the antenna, you will hear the latching relays click into place it should take a second or two if you have set up correctly.
Using the AH-705 Automatic Antenna Tuner
Once set up if you change frequency simply transmit a carrier and the AH-705 Automatic Antenna Tuner will do exactly what it claims to do. It will automatically tune to the frequency you are on. For my quick test last night I laid a long wire across the garden and raised one end about 2.5m above the ground sloping down to the tuner which I hung on the back of a chair (don’t tell the wife!) I also attached some ground wires 3 or 4 measuring about 5m long for each one.
I was able to quickly tune on 3.5 to 28Mhz (1.8 did not tune as the wire was not long enough) excellent results on receive, you can see from the PSK Reporter map that with 5W using a mixture of JS8Call and FT8 the results form my TX was quite acceptable.
Weighing in at just under 600g or 1lb 5oz (including feeder/control cables and 2xAA batteries) its light enough. Its not tiny but can be held in the hand and more importantly fits into the LC-192 backpack.
Initial thoughts are I am very happy with this tuner its well designed and well made although not rugged it feels like it can take a bit of punishment. In use its simple to operate and works very well.
I intend using this tuner to complement my exiting antennas giving me additional scope for experimentation and more options for lightweight antennas. I never thought that the IC-705 should have had an internal tuner, normally internal tuners wont deal with SWR higher than 3:1 which I feel isn’t too useful.
If you always use resonant antennas then you dot need this tuner. If you want to make your radio more versatile when it comes to antennas I would recommend the AH-705.
Look out for more about this tuner and the IC-705 in the next few days. Video of it in use coming as soon as I can find the time.