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”
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…
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 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…
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.
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”
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”