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 www.lmkts.com and will be available very soon.
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).
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 thangs.com (https://thangs.com/mythangs/file/30489) 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!
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!
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.
The PWRpath is an interesting and handy device that allows a load (in this case, my station equipment) to be powered from a mains PSU while simultaneously charging a backup battery. In the event of a mains power failure, the load will automatically switch over to battery power with no interruption of the power supply.
I’m a big fan of PowerPole connectors and have been watching the Chunzehui F-1005 on Amazon for some time. It was a bit more that I was willing to spend at it’s regular Â£59 price point but it want direct to my basket when it recently went on special offer for Â£29.50.
It’s well made with a sturdy steel case but what lurks underneath?
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”
You’ve probably seen the MLA-30 Active Loop Antenna on Ebay. It can be had for a bargain price of around Â£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!
I’m attempting to gain my US licence and it seems that I’ve inspired a few others to do the same. There’s a few prerequisites that need to be in place before you can sit the exam so I thought I would do a quick and dirty guide for what you need: Continue reading “US licence for a UK Ham”
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 Â£2) so we decided to test how well the unknown mix ferrites worked. Continue reading “Using cheap ferrite beads for an LFA choke”
Many people have asked for a better copy of my original FT-857 Manpack Frame over the past 5 years and I usually email a copy to them. Now, I have managed to get round to creating a larger print version for anyone that is having trouble reading the original file or who can’t open the DWG file.
I recently won a bargain Ebay auction for 4 x Hytera SM18N4-Ex hoping they would work with my PD785 handhelds. Unfortunately, I was wrong but the good news is that I did manage to figure out how to make them work!
I love the Hytera PD785 and MD785 radios. When compared to my Motorola DP4800 and DM4600, it only took me a few hours to decide that I prefered the Hytera but there was one thing that I didn’t like, the ‘comfort squelch’ as Hytera call it. Continue reading “Hytera PD/MD785 “Waterfall” noise”
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 Â£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”
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.
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.
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”
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”
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”
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…
I purchased my trusty SGC-230 Smartuner around 8 years ago as a faulty unit and soon got it back up and running with a new binary counter IC. It’s worked great since then but has always had a cracked ceramic post on the output terminal. It was one of the jobs I wanted to do but I never got around to finding a new post so when I had time to replace it, I never had the part handy. Continue reading “SGC-230 Ceramic post replacment”
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”
The Kenwood TM-V71 is a great dual band mobile set that is at home in the car or the home shack. It’s packed full of great features and has a good power output of 50W on both VHF and UHF. I’ve owned Icom, Yaesu and Kenwood dual banders and I just love the TM-V71 so it’s no surprise that I snapped up an ebay bargain for a faulty one (dated 2009) when I saw it. Continue reading “Kenwood TM-V71 Filter Issue”
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.
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 Â£103 excluding postage so I opted to test out one of the Chinese TCXO available on Ebay for under Â£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”
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…
I’m lucky enough to have been given to opportunity to become the next keeper of the GB3EK repeater, an iconic 70cm repeater on the South East coast with 40 years of history and service to the local Amateur Radio community.
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.
It’s early days but I’ve already issued the first award certificate and I know several others are working towards getting theirs.
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”
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…
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).
I found a nice ICOM IC-7200 for a good price and have started work on installing it for use as a (heavyweight) portable HF voice and data station. More to come soon but here is a small taster of what’s ahead…
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.
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.
My poor FT-857 has had a rough life. It’s been used portable and usually ends up being thrown in a bag with the ATU, battery and other parts. I decided it was time to show it some respect and create a military inspired manpack to keep it safe and secure.
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…
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.
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.
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””
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…
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.
White noise. Some people love it, some people hare it. I am one of the latter so the promise of an open squelch and a reduction in noise was one that I could not resist. Continue reading “bhi Desktop noise away”
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”
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”
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!
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.
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.
So the weather station has been up and running for a while now but something has been bothering me. About twice per hour I get a “lost sensor contact” message from the software. Occasionally, it looses contact for a few hours at a time before it comes back. Continue reading “Lost sensor contact”
So I took part in the 2M UKAC again last night. I wasn’t expecting much as I was going to use the collinear on the side of the house but at 17:30 I decided to go outside and put up the 2M beam that I had just acquired through a swap. Continue reading “UKAC March 2011”
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”
So there I was, minding my own business and having a good time working some GOTA stations on 40M when HAARP a Stanag transmission decided to make an appearance and wiped out the band! Continue reading “Stanag on 40M”
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.
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.
High altitude ballooning is an interesting hobby where you can launch a balloon into near space (100,000 feet) with a payload attached. The payload could consist of an RF tracking device so that you can follow the balloon, a digital camera to take images or an array of sensors like temperature, pressure and radiation. Continue reading “High altitude balloon antenna tracker”
Following the death of my cheap fibreglass tri-band collinear, I decided to have a go at constructing a simple dual band antenna for use at home.
I was looking for something that was vertical, omnidirectional and with good gain that I could make quickly and easily. The answer came from Sean, M3FVB in the form of his excellent article on building a 8db collinear.
I was itching to get on the air with my new FT-857 so I made up a quick and dirty set of simple interface leads.
The FT-857 has a data port on the back and a digital mode that is selectable from the menu system. It also has a data port VOX function so any audio being presented on the data port will activate the TX.
After making a batch of nice folded dipole elements on my diy jig, I needed to work out how to mount them andÂ feed them with 50 Ohm coax. The feed point impedance should be 200 Ohms so I needed a 4:1 balun.
I’ve got a strange fascination with folded dipoles. Single or stacked and phased, I just can’t seem to shake the need to build one from my head. So toady I have made a simple jig to help bend up a batch of folded dipoles.
Having read some reviews of the Eton G3 I have found out that some of the early units suffer from poor ssb sync using the built in sync function. My G3 is a very early (sub 300 serial number) unit although I only purchaced it a few weeks back. Continue reading “Eton G3 poor ssb sync”
I was getting a little worried about how the SMA connector on the Icom IC-R5 was dealing with being connected and disconnected from the antenna at home. I take the R5 with me everywhere and once I get home it goes on the desk and gets plugged into the collinear on the roof which has a BNC connector. Continue reading “SMA – BNC adaptor”
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).Â 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.