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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”
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 £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.
Have fun building!
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!
There’s 2 ways to do it, one is the no damage approach, the other involves a destructive modification
but could be reversible. Continue reading “Hytera SM18N4-Ex hack!”
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 £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”
Just some images for my own reference that may be useful for anyone else with a faulty MTP850 S panic button or screen.
Continue reading “MTP850 s panic button and screen replacement”
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”
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 £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”
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…
It’s been a while since I featured my FT-857 manpack on here and I’ve been using it well for over a year now so I thought I better show some sort of update.
So here it is. The FT-857 Manpack as it stands today…
The pack all ready for use…
Continue reading “FT-857 Manpack revisited”
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.
Take a look at www.arpoc.org and let me know what you think…
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’ve got an ever increasing noise floor at my QTH so I thought I would try an active HF loop to see if I can null out the worst of the noise.
I found a simple design on-line and used it as the basis of my loop. The original site unfortunately no longer exists but I did manage to save the design here. Continue reading “Active loop antenna for HF”
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…
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.
Had a great time at the Manston Spitfire and Hurricane Museum today setting up and running a special event station for museum on the air weekend.
We had 2 stations set up, one on 40M and a second on 20M using the excellent 5B4AGN bandpass filters that I made to stop the stations from interfering with each other.
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…
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.
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.
Here is the final call log for GB0NFL over the ILLW weekend 2013. We made a total of 217 contacts of which 2 were duplicates giving GB0NFL 215 unique contacts during 7 hours of operating.
If you worked us and your call is listed wrong then please contact me so I can correct it.
A quick post about my homebrew 100W dummy load.
Made by following the excellent instructions over at http://www.k4eaa.com/dummy.html, the basic dummy load is easy to build, cheep and effective. Every shack should have one. I used a 1 Litre paint tin and filled it with liquid paraffin to keep things cool.
Continue reading “100W dummy load”
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””
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 aprs.fi via my own igate.
Next up will be a test with it installed in the car.
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”
I’ve had a vertical up for a while now but it was just a quick and messy install to test the results.
I have been pleased with them so have decided to have a go at installing the vertical in a better position with a more permanent solution…
Continue reading “Homebrew multiband HF vertical”
Yay! I am now posting sstv images to the website.
I leave the receiver on 20M (14.230) most of the time so take a look at http://www.m0lmk.co.uk/sstv-images/ to see what I have recently received.
You can also check out the archive – http://www.m0lmk.co.uk/sstv-images-archive/ – where the last 300 received images are stored.
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”
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”
I have started on the tracking transmitter that I will use to send dummy date to the HABAT via dl-fldigi. I have ordered a few GPS boards to use in the project and since I already have a Radiometrix NTX2, I have started work on the transmitter.
Continue reading “Basic tracking transmitter”
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.
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”
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.
I love a good Yagi. I also love folded dipoles. So why not mix the two up and make a nice Yagi driven with a folded dipole?
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). 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.