IC-705 REVIEW LONG TERM

IC-705 THREE YEARS LATER

Three and a half years ownership of the ICOM IC-705 have passed and I thought it might be an idea to take another look at it to see if it still rules the roost for Portable Radios in 2024. In this 'look back', I'm only going to focus on what I've been doing and how well the 705 has worked for me. My original review is >>HERE<<

What should I compare it to?  Well I guess a KX3 would be a likely candidate but boy, they are not only difficult to obtain right now, but they're also incredibly expensive unless you buy an old, early production one.

But has the Elecraft got the better receiver? Yes - there's little to beat the KX range in terms of outright performance, that's a given! If you want to hunt down the very faintest, weakest signal, then you stand a better chance of success with a KX.

But for the other 99% of the time, when you've driven, walked, hiked to the perfect take-off spot and set up your antennas, there's little practical difference between a KX3 and the 705. Or between a 705 and an 817. In fact, my $89 (tr)uSDX will probably get you as many QSO's in the log as the others from the top of a hill!

Over the last couple of years I've relied almost exclusively on my IC-705, using it outdoors, on hillsides, in the back garden, in a park, at the caravan, by the seaside and even at home as a base station. It's been utterly reliable and surprisingly tough even though it's not been wrapped in cotton wool. Unlike my Elecraft, I've never really worried about it - I guess I look upon it as a bit of a workhorse. If it gets a little scratch or a ding, it doesn't really matter. I don't believe it would substantially affect its resale price either.

The notable difference between the IC-705 and other radios  is flexibility, features and what I call 'friendliness'.... 

The Icom IC-705 is more feature-rich than any other portable radio. It puts together such an awfully good package that you don't have to buy anything else (assuming that you use resonant antennas). You can operate throughout HF, 6M, 2M and 70cm on LSB, USB, CW, AM, FM, DV and DSTAR. 

With the radios built-in server, you can operate remotely. With the built-in WiFi you can tether to your mobile phone and operate Digital Modes out in the field. Thanks to the built-in GPS, you can even ensure accurate timing for FT8, etc. 

 

Forgot to take a pen for logging your QSO's?? Don't worry - you can record all QSO's onto the SDCARD and run back through it later to get the callsigns - it even records the time and date of each individual QSO!! How good's that??

After using it so frequently and for so long, I'm now in that happy place where I know I just need to grab my small rucksack and head off outdoors for some radio fun. I don't need to carry a million bits of ancillary items - it's just my radio, my antennas and my iPad. If I'm just going out for a couple of hours, then I rely on the Icom battery, but if I'm out for the day I will take a 13.2V LifePO too.

Up on a hillside, I tend to stick with 5W and there's little need for more. Usually, the take-off is excellent and my SotaBeams Dipole works amazingly well - enough to have SSB chinwags across to America from the UK. In fact, one of my favourite chats was from a beach to two hams in America using only 2.5W (KE5EE and WD4NGB).

If I'm struggling to get a response to my CQ calls on 5W, I might move up to 10W, but once I establish contact with someone, I ask them to let me drop to 5W and get another report. If the report is very good (it often is) then I'll ask for another at even lower power. Needless to say, I don't want to make the QSO hard work for the other operators, but most people are happy to experiment with me and they often end up dropping their power to me too and because they've been so used to knocking out 400W+ for years, they've forgotten how far they can get on a tiny fraction of the power. All very entertaining (to me at least) 😂 

I have to admit that it's easier to answer someone elses CQ Call than it is to get a response to your own CQ Call at QRP levels. But patience often does reward. I find that using the IC-705's TX Memories makes light work of repetitive calling. I have a Long and a Short CQ Call recorded in memory and it's easy to set a TX-Loop going. The call is repeated over and over with a small pause inbetween to allow you to listen for any responses. 

Once I've finished with SSB, I tend to briefly switch to the 705's CW TX-Memories and put out a "CQ TEST"  for a few minutes on various bands to see how far I get on the Reverse Beacon Net before switching over to DSTAR depending on how close I am to a repeater. The IC-705 comes with a comprehensive list of repeaters already programmed in and thanks to the built-in GPS it can quickly determine which repeaters are the closest to your location and list them in order of distance (showing you the distance of each one in miles or kilometres).

After DSTAR I might switch to FT8 which gives me a chance to grab a drink and a sandwich. 

The IC-705 has proven to be a true all-rounder and can seemingly do it all, without any fuss or alterations or expensive plugin modules. The only thing that isn't included is an ATU, but neither does the KX3 come with one (unless you pay almost £300). Most of my portable antennas are resonant, so I usually have no need for a tuner, but if I want to use a multi-band end-fed, then one is required. 

I own two ATUs - the LDG Z100PLUS and the Elecraft T1. My favourite is the Elecraft T1. It's compact, light and incredibly good at finding a match - quickly!! And finding a quick match is very important when it comes to QRP equipment because many QRP Transceivers don't seem to have a very robust PA, resulting in blown transistors during long tuning sessions.

Thankfully, the 705 is pretty strong in this respect and I've never had a problem when tuning up using any of my tuners.

The success of the IC-705 in the marketplace has led to much third-party and community support. One of the most useful addons for the 705 is Marcus Roskosh's SDR-CONTROL app which not only provides remote-control operation, but also provides a host of other tools which make the 705 (or 7610 or 9700) an absolute dream to work with. It's a game-changer.

SDR-CONTROL is available on IOS or MAC and I personally use it with my iPad 11. It performs flawlessly with virtually no lag between the readings on the radio and the readings on the iPad. It's all very fluid!

 

All the functions of the radio are available on the software display and the bandscope and waterfall are superb!! It's nice and easy to adjust the bandscope to increase the signal-peak display size and the ratio of scope to waterfall. The meter is nice and clear but I was hoping for an analogue option which isn't there (in the current version). Long-pressing the "TUNE" button sets the power to 10% (adjustable in menus) and transmits in AM mode so that any attached tuner will activate safely. Long-pressing the PTT button will allow you to choose between the radio's mic or the iPad's mic.

VFO A and B are visible onscreen and it's easy to switch between the two. Everything is very intuitive and there's never a struggle to figure anything out. Take FT8 for example - you can switch to it and be making contacts within seconds! No fiddling around with cables, no special drivers or VACs - it just works. Simple!

 

Any FT8 contacts that you make are logged automatically and that brings me to the next feature in the SDR-CONTROL toolbox - the LOGBOOK. Yes, there's a logbook built-in and it has an easy export function to transfer your contacts to your QRZ, etc.

By clicking on a button, you can see the full contents of the ToolKit which includes some very handy features such as the DX Cluster. This can show you active signals on the bandscope, allowing you to quickly spot and engage desired DX. There's also a BandPlan, a set of CW Macros, QRZ LookUp and PSK Reporter. 

There's lots more to this amazing App and it adds so much to the already pleasurable IC-705. I suggest that you go read the manual by clicking on the image below to find out much more about it...

Click me to read the SDR-CONTROL Manual

So, as you can guess, I've been very happy with my 705 - probably more so than any other radio I've owned (and that's saying something). It does pretty much everything I want and it does it all simply, effectively and without fuss. I can play on all the ham bands, in all the modes, I can do analogue and digital and I can enjoy fantastic support from third-parties and a knowledgeable community.

What do I dislike?? Not much really - in fact it seems a bit churlish to complain when a radio offers so very much. If I had to be Oliver Twist and ask for more, then.... I'd ask for CW Decoder instead of the RTTY Decoder. Having said that, the 705 interfaces very easily with my PreppComm Morse Encoder/Decoder....  

 

I do believe that the IC-705 is genuinely the best portable transceiver ever to hit the market. It offers such great value for money and has so many features and functions. And it's not just about the specification list - it's about how everything works - it's incredibly intuitive. Everything falls to hand and makes sense.

There's so many features which make life easy for the operator and where some radios end up looking like a bowl of spaghetti when trying to do something different, the IC-705 often does it wirelessly via WiFi or BlueTooth. Even small things like getting a pair of AirPods working - I've come across so many radios which have BlueTooth but then fail to connect to BlueTooth headsets! The Icom even works with Yaesu's headsets! The very fact that you get a server built into the radio to enable remote operation is pretty darned amazing - especially when you consider that even Yaesu's £3,100 Flagship 101 doesn't have such a feature 😮.

And yes, the £45 SDR-CONTROL software significantly adds to the richness of the 705 which some might say is down to Marcus Roskosch and not the radio, but the fact that the Icom is flexible enough to permit such interaction/connectivity is something that should be applauded. 

Okay, so what about something other than a KX3 or 705? Let's say you bought an FT818 or a G90 or a TX-500?

Well for a start, I wouldn't even give the Russian-built TX500 a second thought because I wouldn't want to support the economy of the disgusting terrorist Putin. Although the HF TX-500 is a very visually appealing transceiver and is around 2/3rds of the price of a 705, it lacks most of the features that I personally value. 

The G90 is a fabulous budget HF transceiver which offers lots for little, but at the end of the day, it's a cheap Chinese radio which I could never consider to be my 'forever radio'. Like the TX-500, the G90 lacks valuable features.

The FT818 is an old favourite of most hams. It's been out there for over 20 years and at half the cost of a 705 is always going to be the QRP radio of choice for people who are happy with the basics. But let's face it, it's old technology and looks like a dinosaur compared to the 705. A rugged, reliable shack-in-a-box but limited in a modern world.

So in summary, I am still over the moon with the Icom IC-705 and I'm glad I invested in it. In the past, radios have 'come and gone' but this one has stayed with me and I can't imagine a time when I would swap it for something else. Maybe Yaesu will bring out something to compete, but I can't imagine how they'd actually make something better! If they do, I'll be all over it 😁

HIGHLY RECOMMENDED!

Please remember that these are just the opinions of an M7 operator. My goals, desires and requirements will be different to yours. I'd be interested to hear about them. Please feel free to leave a comment below and include your CallSign if possible. 73, Tom. 

UPDATE <<<<<<<

Read THIS POST to see how I connected the 705 with an Expert Electronics ColibriNANO SDR receiver to provide a large screen panadapter.

UPDATE <<<<<<<

Read THIS POST to see how easy it is to use an external amplifier with the IC-705, in this case an MX-P50...

UPDATE <<<<<<<

I paid over £20 for my tilt-stand and although it's good for shack use, it makes it a little awkward to fit neatly in my ruckshack, so I've started using a couple of 25mm roundhead bolts instead. Takes seconds to lightly screw them into the base and it results in the radio being tilted to the perfect angle. I got the screws from the local £shop in one of those little multi-pack screw sets. 

SMA Caps hot-glued to bolts
to provide non-slip solution

Quick 5W QSO - internal battery

ICOM IC-7100 PANADAPTER

A SIMPLE PANADAPTER SOLUTION

The Icom IC-7100 is an amazingly versatile little radio, loved by many and underrated by more. It's the only 100W mobile transceiver in the world to provide you with HF, 6M, 4M, 2M, 70cm and DSTAR in the world.

As good as it is (read about it here), it lacks what many people want these days - a nice colourful scope and waterfall. Of course you could always add an external sdr receiver and share the antenna between it and the IC-7100, but then you'd run the risk of blowing your SDR's front end when you transmit, so you'd have to find a solution to that little problem.

Wouldn't it be much nicer though if the IC-7100 had an IF-OUT port on the back? Well sadly, it doesn't - but you can add one and you'll be pleased to hear that it's quite a simple task as long as you're okay making some soldering connections inside your radio (don't worry - they're very easy to do).

SDR-KITS offer a range of Panoramic Adapter Tap boards to fit most radios and the one for the IC-7100 is the PAT150M. The kit I purchased was the cheapest at £12 which is basically, the pcb and nothing else! What I should have bought is the pcb and one of their fitting kits which provides you with a length of coax terminated with a chassis-mounted SMA socket.

Without the fitting kit, I had to use an SMA-SMA lead that I had spare, which meant the connector would be floating at the back of the radio - no big deal, but if I was to do it again I'd definitely buy the fitting kit.

To do the job, you'll need the PAT V board, an SMA lead (or the official fitting kit), some double-sided tape, a small ring-terminal, some solder and ideally, a hot-glue gun.

The first job is to remove the top and bottom covers of the IC-7100 which is a simple task involving unscrewing 6 screws on each cover (they're all the same size).

Looking at the photos below, you will quickly recognise where the PAT V has to be located. It goes underneath the radio onto the main board and fits over the area where there's 10 large soldered connection in a circle as shown in the image below. You can also see in this diagram the other locations we'll be connecting to...

 

Those 10 pointy solder connections are the reason we want to isolate the PAT V board. Cut out a piece of the double-sided tape to cover the underside of the little pcb, making sure that the tape is fractionally larger than the pcb. You could use that common foam-filled tape, but I went for 3M VHB Tape which you can buy on a small roll.

Knowing that I would have cable passing over some nearby connections, I also added an extra piece of 3M tape to make sure no stray wires came in contact (yes, I know there should be no stray bits, but better safe than sorry).

When you're ready to fix the PAT V board into place, make sure that the far two solder connections of the ten remain showing and align the board to match the image above (note I have drawn a blue line to help).

With the board in place, you can make up a wire to bridge the connections shown in the image (the single red wire).

Then route your coax from the rear of the IC-7100 to the PAT V board and solder into place as shown in the image. This was my chosen route, but there are many options available to you depending on where you want to connect your external receiver. There's even a route to the front of your IC-7100, but it's trickier.

With that part done, it's time to finish the final connection to the PAT V board. Fix a small ring-terminal to a wire and fix it to the ground screw on the radio's pcb. Then solder another piece of wire to the connection shown in the image below. NOTE: I used a hot-glue gun to keep the wire fixed in place close to the pcb.

The other ends of these wires go to the PAT V board as shown below. Finally, make a small link wire to bridge the PATV board to the third connection.

That's it! Reassemble the radio and test. I used an SDRPLAY RSPDX for my external receiver, but you can use any similar product. The software I started with was SDR UNO but I also tested it with SDR CONSOLE and both were spot on!

Once it's up and running, you can use the external receiver as just that (an extra receiver) or you can use it to provide you with a panadapter for the IC-7100's using Omni-Rig to keep the radio and the external receiver's frequency locked in together.

There are a few panadapter options out there for the 7100 but I reckon this is the most simple to fit. And it's cheap too!

 

73, Tom, M7MCQ.

 

 

 .

QRP-LABS QMX *PLUS* PART-1

Last Easter I built a 5-band QMX and although I found it quite a challenge, it worked from the get-go and I was really pleased with myself! I get a lot of pleasure from building electronic kits and this will be the sixth one from QRP-Labs. 

My only gripe about the QMX build was that the design left the components incredibly tightly crammed in, and I wondered why they hadn't made the PCB just 10mm wider. But since then, I have read Hans Summers' document explaining that, for him, it was a design-challenge to come up with such a compact design. Well, he did an amazing job!!

Anyway, here we are a year later and I see that Hans has released the QMX+ transceiver kit. This time, the design has much more space between components and I'm anticipating that the build will be far easier than the original design.

So what is a QMX+?? Well it's a high quality 12-band MultiMode (CW/DIGI) Transceiver which can be purchased as a self-build kit or as a pre-assembled unit - it's worth noting however that there is a very long waiting list for pre-assembled units - maybe up to 6 months 😮

In terms of functionality, the "PLUS" version is little different to the standard QMX but it has the advantages of being able to house a GPS unit, an SWR Bridge, a Real Time Clock (battery backed), a Developer's Kit and maybe even an ATU in the future. Hans also has other "secret" plans for the ongoing development of the QMX+ including SSB Mode which will be awesome!

I feel (and I may be completely wrong) that the QMX+ is a big step toward the release of the fabled QSX which will be an All Mode transceiver with who knows what features. 

I currently own a couple of (tr)uSDX transceivers and these are simply amazing little radios which are multi-band, all-mode SDRs with built-in sound card, speaker, mic, keyer, PTT, etc. But their performance is far from perfect. Don't get me wrong - I love them - and when you're up on a hillside playing POTA or SOTA, their performance will bag you many contacts for little outlay. But they're just not in the same league as a QRP-Labs product.

I'll always remember when I built my first QRP-Labs kit - the QDX. It went together well and it performed superbly!! I was getting better results on my 5W QDX than my Multi-Watt IC-7300.  I was (and continue to be) very impressed!

Sorry - I'm rambling. Let's look at the QMX+ Kit. It arrived in a single box which contained all the relevant components, each type being bagged separately.  I'd also ordered the optional GPS Module plus (of course) the metal enclosure. 

The quality of this kit is extremely high and I've yet to come across a QRP-Labs kit with missing pieces. The aluminium case is strong and well finished, with sharp text on the end plates.

The Assembly Manual for the QMX+ is extremely good (as usual) and I intend to follow the instructions to the letter, just as I've done before. 

In addition to having access to the manual electronically, I also decided to print a copy so that I could read through it prior to starting the build and highlight bits which I think warrant special attention, making notes in the margins of the page. I also use the printed manual to mark off each completed section.

I had decided to do this build at the weekend while I was at our caravan - nice and peaceful with no distractions. Prior to going there though, I wound all the toroids and then bagged them individually in tiny sealer-bags with ID labels.

All pretty straightforward but
the most tedious was L506

Before starting the build, I laid out all the components and marked off the capacitor values. Once that was done, I fitted the caps, the diodes and the inductors. Very simple.

After that I installed the BS-170 transistors, clamping them in place before soldering. 

Next up was to install all the toroids and the trifilar. Since I'd pre-wound these, it was a breeze to fit them all and once I've adjusted them as part of the 'tuning' procedure at the end, I'll probably drop a few blobs of hot-glue on them to keep them secure when the radio's in transit.

At this point of the build I realised that I was rocketing ahead and was being a little blasé, so I purposely slowed down and checked everything I'd done so far. 

You will soon notice that some of the solder-pads are TINY and it can be real difficult to get the tip of your soldering iron onto both the pad and the component at the same time. If you look at the adjacent image, you will see that some solder-pads are way, way smaller than others and some of the pads are barely visible. This is a multi-layer board and the ground really sucks the heat from your soldering iron, so make sure you use a decent one that can cope with it.

When it comes to winding the T501 Transformer, you have to decide whether you want a 9V radio or a 12V. I opted for 12 and for this you are strongly advised to choose the "RWTST" method of winding (Really Weird Twisted Sister Transformer) and boy, it certainly is weird!

I'll be honest and admit that the first time I wound T501, I wasn't confident I got it right, so I unravelled it and started again. I was struggling to understand the diagram (see below).

Diagram From The Manual

In the hope that it will help others, I have redrawn this and although it makes sense to me, it may not to you 😂....

After that, I put the two power boards together and fitted them to the main pcb. You have to be very careful to read the instructions and slow down when you're fitting these. Read a couple of pages ahead before beginning!! I totally forgot that the black connectors have to be mounted so that there’s a gap below them. I just about managed to get away with it (der!).

 

I then started fitting all the 'hardware' such as the BNC connector, power connector and 3.5mm sockets before installing the LCD panel and battery board.

With everything installed (don't forget the link under the GPS Board (if you bought one)), it was time to slide the PCB into the lower half of the enclosure. 

Before you do though, spend some time examining the pcb to see if any of the component legs need trimming down, because there's very little space between the underside of the pcb and the metal enclosure and it's very easy to end up with a short. 

I purchased some amazing little side-cutters from the local £shop which were perfect for the job! To be honest, I thought they might be junk, but they turned out to be the toughest fine cutters I've ever bought, so I went back and got another pair 😊

With everything put together it was time to apply power and see if any smoke emanated from the case 😬. In case I'd made a mistake (or two), I opted to use a current-limited psu to avoid damage on power-up.

 FIRST TEST >>>

When I switched it on, there were no lights, no display, no noise, nothing. And thankfully there was no smoke!

Before anything will work, you have to connect the radio to a computer with a USB lead and install the firmware, but when I did this, the USB was not recognised. I tried a different lead and even a different computer - nothing! 😰 

I checked and double-checked the pcb for any obvious signs of faults such as dry joints, solder shorts, etc, but there was nothing obvious. I could see 9V at the power switch.

I sought help on the Groups.IO forum and got nowhere initially, so I submitted a trouble-ticket at QRP-Labs but six days later there was no response from that either.

It's extremely disappointing when stuff like this happens and I know there's bigger problems in the world, but neverthless I'm feeling quite disappointed considering that I've successfully built 5 other kits from Hans (including the regular QMX which is much tougher build) and a few from other kit manufacturers.

A few days on and members of Groups.IO started to make suggestions and I learned that there should be voltage at Vcc and Vdd but there was none on mine. The thread got busier and someone suggested that I try swapping out the Power Boards from my QMX to my QMX+.  To reduce the risk of damaging anything, I was using a variable voltage/current PSU.  With it, I could reduce voltage to maybe 7.5V and 200mA.

Before swapping out the boards, I recalled my soldering struggles and decided to reflow virtually all the connections to make sure that I'd not got a bad joint somewhere which was causing these issues. The Ground Plane on this pcb really does suck the life out of your soldering iron! 

I decided to remove the power boards and the GPS module. It was then that I discovered I actually had a short on Vdd. No amount of probing with my DMM helped discover the source of the short, so I’ve given up for now.

I’ve approached an electronics professional friend to see if he can afford the time to do some fault-finding for me. If not, I might have to order another and start all over again 😪.

Part-2 to follow!

UPDATE >>>

Regrettably, my friend is in the process of moving to another country(!) so I'm now proper stuffed 😂 I guess I'm going to have to write this off completely. 

I was thinking of ordering another one and trying again, but this build has made me a little weary. Plus it's highlighted the fact that without any electronics knowledge, I've just been a lucky constructor up to now.

I'll have to sleep on it 😓

UPDATE >>>

On a more positive note, G4GIR very kindly offered to look at the board for me, so I've popped it in the post to him and await his verdict. Let's hope it's nothing I've done 😂😂😂

UPDATE >>> 4 July

Ian G4GIR has carefully examined the pcb and has determined (with the very kind help of Jeff Moore W1NC) that the fault is with the main CPU, so that's nothing to do with me or anything that I've done wrong. In fact, Ian complimented me on my construction work.

So I have written to Hans and I await his response - a positive one hopefully.

UPDATE >>> 11 July

Hans has very kindly shipped out replacement pcb and components to allow me to start from scratch. I will be looking for ways to carry out checks stage by stage from the forums this time.

73, Tom, M7MCQ.

MAT-705 PLUS ATU

BEST ATU FOR IC-705?

For the last few years I've been using the amazing ELECRAFT T1 with my IC-705. Well actually, I've been using the Elecraft with all my QRP radios and I've been extremely happy too!

My only gripe with the T1 has been the lack of an interface cable. Elecraft have been saying for years that they are making a lead for the IC-705 and it's just never materialised - annoying!

Anyway, when Icom introduced their AH-705, I thought it would be worthwhile investing in one, but at £300, I quickly changed my mind! And apart from the silly money, they're also quite big and heavy considering the application.

I'd previously looked at the Mat-705 but the first version of it was not very highly rated, so I gave it a miss. When the PLUS model was introduced, it looked to be much more interesting, so I looked further into it. It too was a bit pricey when it was launched, but I was always going to wait for one to appear on the second-hand market anyway.

MOONRAKER 

I found one on Facebook Marketplace for £100 including postage. Bargain!!

The MAT-705 PLUS brings USB-C charging to the tuner and a redesign which removes the need for an On/Off switch. The unit turns on automatically when plugged into the radio.

The unit is small, light and looks pretty robust. It is not, however, waterproof. Some people are complaining about that, but it's not something that bothers me at all - I don't work in the rain either 😂

The MAT-705 comes with a USB-C charging lead and a 3.5mm TRS interface cable. The LEDs on the faceplate are large and bright - easy enough to see in bright sunlight.

The tuner has thousands of memories, which makes tuning super fast once it has learned the antenna its connected to, but even on a fresh tune, it only takes a few seconds anyway. It's pretty quiet too (especially compared to something like an LDG Z100PLUS).

Tuning through all the bands

I've got my MAT-705 and IC-705 configured to tune on PTT which means everything is just automatic - I simply press the PTT on the mic (or the VOX button on the radio) and tuning instantly begins. It's seamless and effortless.

If I'm using my Elecraft T1, I have to make sure I'm on 5W, change mode to RTTY, press the tune button on the T1, key up and wait for a tune, then change the mode back and adjust the power (if needed). A bit of a faff.

So having played around with the MAT-705 PLUS, I have to say I am impressed! I love the compact dimensions and the integration. Some people have complained about the battery life between charges, but it's not something that bothers me too much, because I'm always careful to prepare for a day out playing radio.

I always charge things which need charging the night before and in addition to that, I'm anal enough to always carry a USB Battery Pack with me.

So in summary, I think this is a fabulous IC-705 companion and it means I can leave my Elecraft T1 in my FX-4CR case.

 

USING THE MAT 705 WITH OTHER RADIOS

Neil, G1AAD wrote to me, telling me that he’d figured out a way to use the tuner with other radios and he very kindly put together this document to explain how it’s done….

Manually using the MAT 705 Plus ATU with any radio.

There is basically a two line interface (plus ground) between the IC-705 and the Mat ATU. The Key Line and Start line.

The Key line coming out of the 705 to the Mat tuner has 3.3V on it. When connected to the Mat tuner this drops to approx. 2.7V and basically tells the Mat tuner to wake

up and power on. At the Mat tuner end this allows the Mat tuner to tell the 705 to keep the transmit on until the ATU tuning cycle has finished.

With the Mat tuner is connected it wakes up and then puts 5V on the Start line which goes back to the 705. This tells the 705 it is connected to the tuner and illuminates

the Tuner icon in the Function menu.

On transmit the 705 pulls the Start line to ground to tell the ATU to start the tuning cycle. Once the tuning cycle has started the Start line is released after approx. 1 second and goes back up to 5V. But this timing isn’t critical which is helpful for us because this starts the tune and can be done simply with a momentary push button switch.

During the tuning cycle the Key line is held low by the Mat tuner and is released high on completion which stops the 705 transmitting. The 705 tune power is also reduced for tuning.

So all we need to do is to put approx. 3.3V on the Key line to wake the Mat tuner up and manually pull the Start line down just before pressing PTT on your connected transceiver, then release the start line and wait until the tune cycle has finished. When you hear the relays stop chattering release the PTT. Remember the Mat tuner will remember frequencies so subsequent tunes could be very short.

Unlike the 705 you will not get any indication that any particular tune has not been successful. This is signalled to the 705 using a pulse on the Key line just before it goes high and TX stop. You will have to use your own connected SWR meter or transceiver display.

I chose to use a single 3.6V AA sized battery (search for 3.6v lithium aa battery on Amazon). The diode is to drop the voltage a little to match the 705 and the resistor is to

limit the current taken by the Key line again to tie with that found on the 705. The current taken down the Key line is approx. 10uA and 70uA in Tune so the battery will last a very long time. Once tuning is complete the switch can be turned off as well because the Mat tuner has latching tuning relays and full pass through on power down.

So tune procedure is :

 Connect up – reduce TX power

 Press Start - then press PTT – then release Start (after approx. 1 sec)

 Keep PTT pressed until tune cycle finishes

 Switch off if you want

RISKS and unknowns.

 I measured the current being drawn down the Key line from the 705 and chose the components below accordingly. The Start line is pulled to ground inside the 705 anyway so a momentary switch to ground is fine. So confident on the circuit and the procedure.

 The key risk as I see it is the transmit power to tune. The 705 tune protocol deliberately reduces the output power for the tune whatever the 705 transceivers power setting – you MUST remember to do this manually on your transceiver. It looks like the 705 uses less than ½ Watt to tune and then jumps up to full set power after tune. This means you would need an in-line >10dB 5W attenuator for something like the tr(u)SDX but the FX-4CR could be turned right down to a lower setting. 

There are no obviously big load resistors inside so I would definitely stick to less than ½ watt for tuning to avoid damage to the tuner. In the AH-4 ATU document there is reference to 350mW tune power which would tie with my power readings – is that relevant ? The more recent AH-705 is quite different at 5 to 10W. 

UPDATE : did some testing with my FX-4CR and it seemed to only tune and get the green LED on when I was transmitting about 1 Watt. Definitely more delving needed here then.

 And of  course then wick it up to no more than 10W once tuned.

Many thanks to Neil for this valuable information - very much appreciated!

73, Tom, M7MCQ.