New store!

I’ve decided to move my store from this website over to it’s own dedicated site. The ecommerce software is much better and very fast. I’ve always sold my products under the “LMK Technical Services” brand which is my sole trading name and moving them to a dedicated site makes this much more transparent.

The new store is located at and will be available very soon.

BT FTTP + Ubiquity USG +IPv6

We’ve recently moved to the new BT FTTP service and enjoy a nice, stable 500Mbps download speed. We’re equipped with a Ubiquity UniFi system in the house which uses a USG (Ubiquity Security Gateway) as out main firewall/router. We connect the Openreach ONT (the white box that Openreach install where the fibre terminates and provides an ethernet connection) directly to the USG and don’t use the provided BT home router at all. This config works great and removed the problems of having a double NAT when dealing with firewalls and port forwards. This also lets us use the USG to load balance a 4G connection (which we use for some specific traffic and as a failover).

Continue reading “BT FTTP + Ubiquity USG +IPv6”

VHF Design QRO LNA Case

I’m designing a simple weatherproof case for the VHF Design range of QRO LNA devices. More details to come but here’s a taster. This was a rough, fast test print to check for fit.

The design is available on ( for free so anyone with access to a 3D printer can make one. I may also have some available on my own store in the future.

Once completed, I’ll produce another design to fit the smaller, 100W rated VOX LNA also from VHF Design. Watch this space!

New 3D Printed Products

I’ve had a 3D printer for some time now and I’ve been experimenting with various settings, filaments and prints. I’ve got to a point where I’m happy with the results and am pleased to announce a new product line of 3D printed items for the Amateur Radio and Shortwave Listener hobby. The first of my new products are these 3D printed feed points for dipoles and verticals to be used with push up “fishing pole” style masts.

The dipole feed points are available in either SO239 or BNC size and have a reinforced hole that slides over the top of a telescopic pole. No more messing about with tape or cable ties! The vertical feed points, also available in either SO239 or BNC have a slot through the mast bracket which allows a 10mm Hook and Loop tie to pass through and allow quick and easy attachment to the bottom of the pole.

Perfect for a homebrew dipole, linked dipole or vertical and available without socket and hardware or with socket and marine grade stainless steel hardware. Check them out on my shop!

IC-7300 In Multi Radio Environment?

In 2019 I organised a trip to a remote farm in Devon for a mini DX-pedition, a sort of radio holiday for a few good friends and club members to play radio non stop for 5 days with 10 acres of field to erect antennas and a non existent HF noise floor. We took three Kenwood TS-590SG sets with us and I was amazed with their performance in a multi radio environment. One was running QRO via an Elecraft KPA500 amplifier and there was never any problems with interference between the operating stations. At one point, we were working CW on 20m @ 100w using a ZS6BKW and working SSB on 20m @ 100w using a DX Commander with around 15m separation of the antennas with no issues. The only slight interference issue we had was if another operator was using an exact second harmonic but even then, most stations were still workable.

Continue reading “IC-7300 In Multi Radio Environment?”

GPS Data for Icom IC-9700

Don’t want to build your own? I now sell these and an alternative design with a better, fixed external unit on my shop!

The Icom IC-9700 has a GPS data input available but no oficial accessory from Icom. It’s a 2.5mm TRS connection that allows users to connect a GPS unit with an RS232 output to the IC-9700 and use that data for DSTAR transmission. There are several GPS units on the market that can provide the data but they are often expensive standalone units or cheaper, older generation units with lower sensitivity and performance when it comes to tracking GPS satellites. Continue reading “GPS Data for Icom IC-9700”

Inside the MLA-30 Active Loop Antenna

You’ve probably seen the MLA-30 Active Loop Antenna on Ebay. It can be had for a bargain price of around £35 and works great for the price. There’s only one problem in my book; the PCB is covered in epoxy potting and you can’t see the design or repair/modify it! Something that I’ll have to fix!

What follows is the results of 45 minutes in the kitchen with a pan of boiling water and a pair of tweezers. Behold, the MLA-30 in all its naked glory! Continue reading “Inside the MLA-30 Active Loop Antenna”

Using cheap ferrite beads for an LFA choke

The contest club I am part of uses 2M Loop Fed Array (LFA) yagis for their QRO station. It’s always been advised to use a choke of some sort as close to the feed point as possible to prevent stray RF traveling back down the outer of the coax and into the station. The cheapest way of doing this is by creating a coax choke using 2 to 3 turns of coax around 2″ in diameter but this is also quite messy and risks fracturing the center conductor or foil in the feeder.

There are several commercial ferrite chokes available which replace the messy coax choke and one of our members has a large stock of unknown mix ferrite beads (which can be purchased in a pack of 5 for under £2) so we decided to test how well the unknown mix ferrites worked. Continue reading “Using cheap ferrite beads for an LFA choke”

External GPS for TM-D710

I’ve been running my TM-D710 in the car for a while using a Garmin GPSMap 60CSX which works well but does add clutter to the dashboard and is just another device to remove when leaving the car in a public place. I could upgrade to the newer TM-D710G but I can’t justify the £550 price tag just to get a built in gps so I have decided to add a gps unit to my existing unit.
Continue reading “External GPS for TM-D710”

Diamond X-300 repair

I did this repair many years ago after the mounting failed on the X-300 (original single bold stub mast) which allowed the antenna to sway. It gave a few more years of service after the repair and mounting modification and was only taken down to be replaced with a new X-510 which has the same mounting modification.

The X-510 has been up for many years with no issues despite being battered by the winds and salt coming off the North Sea.
Continue reading “Diamond X-300 repair”

T2FD Calculator

I love a good T2FD antenna and have built a good few. There’s a few variations but they all work well and are easy to construct. I’ve been asked a few time about the length and spacing so I made a small Excel sheet to work it all out and provide data for the 3 most popular variations.

Free free to download and use. The sheet is protected to prevent the formulas from getting messed up but if you would like to experiment with alternative formulas then please just contact me for the password. All I require is for my original credit to remain on any derivative works.

M0LMK T2FD Calculator

Wideband Noise Source

A cheap but very useful item of test equipment that would be an asset to any experimenter’s tool box. I picked up a BG7TBL Noise Source from ebay and built it into an enclosure.

There are reports that the PCB gets very hot during operation so mounted the entire PCB onto a piece of copper clad PCB which I also used to secure inside the enclosure. Continue reading “Wideband Noise Source”

4:1 BalUn

I’ve been wanting to built a good 4:1 BalUn as part of the never ending project that is my HF antenna system for some time and today, I finally got around to the job. This is a “true” 4:1 Current BalUn that is wound as two separate 1:1 current baluns and then placed together to create the 4:1 ration. Any 4:1 built on a single core that claims to be a current BalUn is lying and is actually a Voltage BalUn! Continue reading “4:1 BalUn”

Ladder Line Surge Suppressor

I usually get static build up on my HF doublet due to sand particles (I live above the beach) in the air so have been thinking about a way to bleed off the static and provide some protection to my TS-590SG. After a little research, I came up with this, a lightning arrestor/static bleed device that provides a permanent path to earth for DC whilst allowing RF to pass and providing protection from nearby lightning strikes. Continue reading “Ladder Line Surge Suppressor”

SGC-230 relay replacement

A common fault on the SGC range of antenna tuners is a reduction in receive performance as they get on in years. This can be attributed to contamination on the relay contacts since SGC stoped using fully sealed relays. Any small condensation inside the tuner makes it’s way into the relays and causes contamination on the contacts as they are hot switched. The best thing to do is to replace all 26 relays with new units…

Continue reading “SGC-230 relay replacement”

TM-V71 fan upgrade

This is a simple modification that takes around 5 minutes but makes a big improvement to the already great TM-V71. The fan on this radio is very loud and runs at full speed from the moment you press the PTT then stays on for a few minutes after you release the PTT. This isn’t a problem in a mobile setting where there is usually more background noise but it is very loud when using the TM-V71 in a quiet home shack.
Continue reading “TM-V71 fan upgrade”

FT-857 / H250 Handset switch and adaptor box

A few people have asked me about the H250 adaptor box that I built to use on my FT-857 manpack. It allows the operator to switch between using the standard Yaesu fist microphone or an Ex MOD H250 handset.

I don’t have any build notes but here are a few images that may help anyone who wants to build one.

Kenwood TS-590SG TCXO

I like to play with digital modes and whilst the TS-590SG is a very solid performer, it does have a nice TCXO available as an upgrade. The “real deal” from Kenwood comes in at a hefty £103 excluding postage so I opted to test out one of the Chinese TCXO available on Ebay for under £20 delivered.

Installing is very simple. Just take the case off, remove the existing empty PCB (the upgrade from Kenwood is just the actual TCXO which you have to solder to the PCB already in place), put the new TCXO board in the move the jumper to the correct setting.
Continue reading “Kenwood TS-590SG TCXO”

TX audio chain

It started as a simple project to construct a switch box so I could use a single microphone with multiple radios in my home shack. It’s ended (although i’m not sure it will ever end!) with more knobs, buttons, switches and flashing lights that the flight deck of a Dreamliner.

I’m still experimenting and will be posting a walk through soon so stay tuned but for now, here’s a little picture…

M0LMK Audio Chain

ARPOC Awards Scheme

I’ve launched a new award scheme designed specificity for radio amateurs who enjoy portable operating. ARPOC (Amateur Radio Portable Operators Club) aims to encourage operators to get out in the fresh air with their radio equipment and enjoy portable operating.

ARPOC has plenty of award certificates that can be applied for and are delivered as a downloadable certificate for members to print at home. Take a look here to see them all.

A sample of one of the award certificates available.
A sample of one of the award certificates available.

It’s early days but I’ve already issued the first award certificate and I know several others are working towards getting theirs.

Take a look at and let me know what you think…

Shack Sign

I do a lot of portable operating which always brings a small problem when I am operating from home. I’m a bit forgetful and tend to forget the simple things like my home QTH WAB square or locator and get them confused with some of my favourite portable operating spots. So, I’ve decided that it’s time for a shack sign. I don’t want any of the garish edge lit, laser cut clear acrylic signs that are quite common, I just want something simple that has my call sign, locator and WAB square on it.
Continue reading “Shack Sign”

Simple ugly choke

Another part of my antenna experimenting equipment. A simple ugly choke for HF made with 30 turns of RG213 coax around a 4″ plastic pipe.


1:1 BALUN for ladder line

I needed a 1:1 balun to use with my home brew doublet but I needed it to go between the ladder line and the SGC-230 tuner so it needs to have stud terminals on both the input and the output. I took a look around and decided that making one was the best option.

It’s made using 11 turns of figure 8 twin lead on two stacked FT240-43 cores. See the pictures below…

Continue reading “1:1 BALUN for ladder line”

QRO 1:1 Choke

I’ve been meaning to build a good 1:1 choke or line isolator for a while now and the parts have been sitting on the shelf for over a year. Well today I finally got around to it.

I chose to build something that would handle the full UK power limit (400W) with no problem and used G3TXQ’s excellent chart to select the best combination of core and windings.

Continue reading “QRO 1:1 Choke”

OpenSSL Heartbleed Vulnerability

Running OpenSSL on anything?

You need to upgrade to version 1.0.1g or patch your existing install right now!

I run a bunch of Debian based system so I upgraded them all to version 1.0.1g (1.0.1e is the default available from the Debian repos but I don’t know if it has been patched so I just opted to upgrade manually to 1.0.1g).

See the security advisory here –

Continue reading “OpenSSL Heartbleed Vulnerability”

IC-7200 Mic upgrade

Just a quick post about the stock microphone on the Icom IC-7200. If you have a “made in China” version of the HM-36 then you can make your audio a lot better.

Forget messing around with the mods listed over the internet and jump right in with a kit from AB5N. His microphone element along with the associated modifications will transform your HM-36 into a great sounding microphone.

I tried 4 different modifications and the AB5N came out on top. Highly recommended.

Portable from the New Forest

Just a quick post to say thanks to everyone who managed to work me this afternoon/evening.

I had a great time working /P from the New Forest with the 857 man pack and a 40M dipole strung up between 2 tall trees. I was using 25W on 40M and managed to work plenty of inter-G stations with Swansea, Newcastle, Chelmsford, Aberdeen, Bristol and Portland all appearing in the log amongst many others.

Getting the antenna out of the trees in the dark was fun but not as much fun as getting it up! I think I need to sort out my antenna catapult and save my throwing arm.

Icom IC-7200 QRS mod

I’m a keen user of ALE on the HF bands and recently purchased an Icom IC-7200 to use as a dedicated ALE station. I picked the IC-7200 as I liked the form factor, the fact that is is a dedicated HF radio and that it has a built in USB interface. The only problem with using the IC-7200 for ALE use is that the TX bandpass filters are switched in and out using relays as the radio scans through the bands. This causes an annoying “click, click, click” sound when the radio is changing bands and, when scanning at 5 frequencies per second, can put considerable wear on the relays. Luckily, there is a fix for this problem…

Continue reading “Icom IC-7200 QRS mod”

Chuffin QRM…

It came in the night

It was a quiet November morning. The baby was asleep after just being fed and no one else was around to interrupt me. The idea time for a spot of radio.

I made myself a cup of tea and sat down in the operating position. 05:04, I should be able to get a hour before the rest of the house starts to wake up.

I powered up the ic-7200 and spun the dial to 40 metres. There was a surprise waiting for me.

Continue reading “Chuffin QRM…”

Baofeng BF-888s charger modification

I have a few Baofeng BF-888s radios and they are great radios for the price but the charger does not exactly fill me with confidence. The drop in charger comes with a single insulated twin core cable which is very thin and a 2 pin plug with a 3 pin adaptor. No fuse and no secondary insulation make it a dangerous mix so I have replaced the cable on all of mine with some proper twin core mains cable and a 3 pin plug with a 3 Amp fuse.

Continue reading “Baofeng BF-888s charger modification”

ILLW 2013

Wow, what a weekend!

Saturday 17th

After months of planning, organising, and working with the local council (who were very good and helpful) the International Lighthouse Lightship Weekend had finally arrived. A keen group of volunteers and Hilderstone Amateur Radio & Electronics Club (G0HRS) members arrived at Joss Bay car park for 11:00 UTC and started to assemble a portable HF station whilst the North Foreland Lighthouse stood tall in the background.

Continue reading “ILLW 2013”

EasyPal Images

I’ve just added a new page to the website that shows all of the EasyPal images that I have received.

At the moment, it EasyPal is only running whilst I am at my desk and remember to turn it on but I hope to have it up and running 24/7 using an SDR soon…

A real “Shack in a box”

We have all seen the black box radios that have attracted the term “shack in a box” but I wanted a real shack in a box.

I have limited space at home and wanted to enjoy a bit of portable operating but didn’t want to spend out on extra equipment for portable use and didn’t want to keep unplugging the HF radio and associated bits. The solution was to build a “go box” or “jump kit” that contained all of the equipment needed for home operation and could also be packed up quickly and used for portable operation.
Continue reading “A real “Shack in a box””

Normal service has been resumed

It’s been a while since I last posted but a lot has happened.

I’ve now moved home and given up working for a living. Well, I’ve given up working for someone else and am now self employed. I now help run the family business, a small guest house by the sea, and have taken over from my parents who wish to slow down and relax a little.

Unfortunately the chickens have gone due to lack of garden space but they went to a good home (my old neighbour).

Those who are observant will also notice that the domain name has changed. Please update your bookmark if you have one.

Stay tuned for more strange projects, radio stuff and general deranged musings…

I’m still here!

I know it’s been a while since my last update but I am still here.

I’m currently in the middle of moving house and becoming self employed so things have been a bit hectic to say the least.

Normal service will be resumed soon.

Simple APRS Transmitter

I started to work on a simple APRS transmitter today so that I could use it as a antenna test bed for Project Swift.

It was very simple to build using only an Arduino Uno, a Venus GPS receiver a Radiometrix HX1 module (on 144.800Mhz) and an SMA PCB socket.

The completed board looks like this…

After playing around all day with the APRS message format, I managed to get it working and updating to via my own igate.

Next up will be a test with it installed in the car.

20M vertical

After deciding that my doublet works better than the multi-band vertical that I built from a 10M fishing pole, I decided that I wanted to try a mono band vertical.

20M seemed the obvious choice as I could use the 10M pole to create a 1/4 vertical with radials.
Continue reading “20M vertical”

PS-30M PSU mod

The Palstar PS-30M (also called the Morning star PS-30M and the Manson EP-925) is a great PSU. Rock solid, heavy built and, most important for radio users, its a linear power supply which means it’s nice a quiet RF wise unlike most switch mode PSU’s that make a lot of noise on the HF bands.

Continue reading “PS-30M PSU mod”

Now with added Android

Just a quick post to let you all know that mattltm is now running a special theme for Android and iPhone users.

It loads fast and makes checking out the site on the go easy.

Basic pan & tilt platform

The pan and tilt platform will hold the high gain yagi used for receiving the HAB signal.

I’ve just got a small, simple platform for now to test with and will upgrade it once everything is working well. It’s driven with 2 hobby servos direct from the Arduino. One minor drawback is that a standard hobby servo only has a round 90 degrees of movement. That is fine for the tilt control but no good for the pan control so I will have to try and source a servo capable of 360 degree rotation that provides position feedback or maybe build a 4:1 drive system for a standard servo.
Continue reading “Basic pan & tilt platform”

GPS antenna fix

I was given a broken active GPS antenna by a pilot friend. It’s made by Gilsson who are known for their great GPS antennas so I thought I would have a go at getting it working.

On first inspection, it seems that someone has removed the original thin coax and replaced it with some thicker coax. There has been a hole drilled in the bottom of the case and the new coax has been inserted through.
Continue reading “GPS antenna fix”

Sparkfun ProtoShield

Just a quick post about the Sparkfun ProtoShield v2 board that I have to help make building HABAT easier.

The board comes in kit form and needs a small amount of soldering to get it ready for use. It’s an easy job with 3 small resisters, 2 small capacitors, 2 LED’s, 2 switches and 4 Arduino header pins.

Here is the completed board:
Continue reading “Sparkfun ProtoShield”

NTX2 TX blip

I finally managed to get the NTX2 and GPS working together thanks in no small part to NigeyS and fsphil from UKHAS.

One small problem still is that the RTTY signal from the NTX2 has a small “blip” in it that destroys the string. This must be an issue with my code somewhere as I can run some demo strings through the NTX2 using some simple code with no problems.

See the blip? Not sure what is causing it but I guess I better find out!


All fixed.

The blip was due to a drop in voltage. The GPS was drawing more current than the power source could supply. Plugging in a 1A 12V PSU fixed the issue.

Camera broken :(

Well I was going to post some nice images of my new 14.8v 5Ah LiPO batery and charger that I will be using to do some portable operating when the weather gets better but the camera on my HTC Desire seems to be broken 🙁

I’ll pop up some images once I work out what is wrong with it.

Olivia 32/1000

I like the digital modes and have been hooked on BPSK for a few months now but started getting a little bored of the same quick exchange format (3 button mode as it was described to me!) so I thought I would try my hand as something new.

After searching around the bands and listening to a few signals I decided to have a go with Olivia. It seemed like a very chatty, casual mode with good DX prospects and excellent weak signal performance.
Continue reading “Olivia 32/1000”

WSPR on 20M

Encouraged by a post on a forum that I visit, I decided to have a go with WSPR (Weak Signal Propagation Reporter) whilst I was working in the shack yesterday.

I set the 857 to 10W output on the 20M WSPR frequency (14.0956) and adjusted to audio input to give 5W total output.

Here are the results…
Continue reading “WSPR on 20M”

Maritime Mobile Pileup!

The call came out /MM and the frequency went wild. Just goes to show that a good prefix gets plenty of attention!

I finally managed to work the station after calling for 30 minutes and managed a 59 from my 10W.

Arduino at the ready

I will be using a Arduino the base building block of project HABAT.

The fact that is is mall, inexpensive and easy to work with are the main reasons that I chose the Arduino. There is also a large community of users who I hope to be able to turn to when I need help!

This Arduino will form the base of the tracking transmitter that I will be building to test HABAT.

Breaking it down

So lets get project HABAT off to a start.

Like any good project, I need to break this one down into bite sized chunks. Here is what I have come up with:

Aim: To create a automated platform capable of receiving the balloons GPS coordinates, performing the necessary calculations to determine the balloons position relative to itself and then actuating a pan and tilt platform to aim a high gain yagi antenna at the balloon.

Sounds simple huh?
Continue reading “Breaking it down”

TG-UV2 Programming cable pin out

I made this up to help out anyone who wished to build their own programming cable for the Quansheng TG-UV2 handy.

The image shows the serial plug that goes on the other end as you are looking at the solder buckets.

Building a Longwire antenna

Having just purchased an Eton G3 radio I wanted to get into Short Wave Listening a bit more. I am generally interested in NAVTEX, DGPS signals and Numbers Stations but the internal G3 bar type antenna just wont cut it.

I initially tried to just throw up a length of wire, stretch it out across the garden and straight into the G3’s ext ant jack (which is a 3.5mm mono jack by the way).  It kinda worked and I could hear a few more stations but it also pulled in a huge amount of noise generated by the nearby houses and electrical junk.

Continue reading “Building a Longwire antenna”