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.
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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.
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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

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…

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SGC-230 Ceramic post replacment

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”

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.
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Kenwood TM-V71 Filter Issue

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”

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.
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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 www.arpoc.org 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.
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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…

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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…

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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.

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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.

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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.
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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 aprs.fi via my own igate.

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

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!

Update……

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.
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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?
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Simple stacked J-pole for 2M & 70cm

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.

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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.

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