I bumped into one of those peoplea few days ago, Kevin, M0KHZ. Kevin is heavily into SDR and more specically HPSDR – High Performance Software Defined Radio. He was also the person who showed me how to solder SMD’s and made it look so simple it gave me the confidence to ruin a few pads and components. Most of which he generously donated to me from his stockpile.

At last years Dayton convention he and a few dedicated others showed a prototype Hermes SDR that was simply breathtaking (at least the box in his shack that he showed me had me wanting one immediately). Since then he mentioned that the project team had been battling with some problem with the boards and as a result needed a lot of head scratching. This thinking time is nearly over and the fruits of his and the rest of the teams labour is at an end. With a bit of luck this years Dayton will have an update.

If you’d like to know more about Hermes and HPSDR then follow this link. I’ve no real clue as to how it all works, I can certainly follow a block diagram but the rest of it is well over my head, I’m just fascinated with the end result. It may not be your thing and if it isn’t you must agree that this type of experimentation demonstrates the unique nature of this hobby. Homebrewing for me is building an antenna from scratch or a simple kit or cable. For others its at the bleeding edge of RF technology. For others its the integration with computers or building cheap and simple sub watt transmitters that get the other side of the world. Whatever the flavour I challenge anyone to come up these levels of innovation, I can only think of astronomy!

There is an interview conducted by Tobias (DH1TW) that gives a load more detail if you’re interested.

Now all I need is a working HF lite (Mine is no longer a happy sdr, may have been damaged when I moved the garage around) and an electrically switch BPF kit. These seem to be as rare as hens teeth!

My own personal reasons are for nothing other than it could be a fun project to build a HF lite kit and electrically switched BPF and to couple that together with a small, arm based (read cheap) computer that could be used to monitor beacons whilst using less than 60 watts of power with a laptop  or netbook and tieing up a rig that I use for HF.

Time for me to make a tidy job of wiring up the HF Lite I built last year and hope that JN1SDD is feeling generous with his secrets. Good thing is it saves me having to save up for a more expensive receiver too:-)

Last night I finished the preliminary build and completed the checks on the build notes. There were a few odd voltages across some of the pins of a U6 and U8 but it seemed to fire up ok and was recognised as a USB device. I was able to change frequencies and connected up the audio. There was a reassuring hiss of the noise I’d expected but slap bang in the centre of every tuned band was an enormous band of noise. None of the band pass filters were installed so this may be a cause but after checking things again and removing the HF Lite altogether the noise was still there. Maybe it doesn’t like my machine, but I’ll check again later and if it’s still there with some filters installed. Below is the screenshot

A few were ‘over soldered’ but the technique developed and after 20 or so attempts they weren’t looking too bad. So this evening I will start on the power supply part of the softrock

So far I’ve borrowed a very nice microscope from a friend who’s into beekeeping and he used it for a bit of bee pathology. It’s way more than I need but useful none the less to use this is much better than to struggle with nothing. New flux pen, solder 3rd hand (although Kevin did suggest that blu tack works just as well and judging by the quality of the boards he showed me it works very well). Kevin also introduced me to some best practice and it was a really useful time. So thanks kevin and I’ll be on S22 when I hit a problem!

Hopefully the rest of the Farnell order will turn up today so i can start putting things together

Whilst I was there Kevin showed me his HPSDR and his Quicksilver receiver and they are simply amazing. maybe one day I’ll be building one myself. First things first lets do the softrock!

So the goal for this kit is to solder it so it works and not to make it look pretty!

After seeking a bit of advice on how to solder the SMD’s I’ve got a few choice as to how I get the components on the board and get them soldered. One thing for sure is that it ain’t going to be a pretty build. I’ll be starting on the build at the weekend and I’ll be posting the progress and without sounding too negatives some of the problems that I encounter.

A few useful links though

SDR official website

Softrock Yahoo Group

Build instructions

Part of the SDR beacon station project is to develop a low power consumption unit so that the impact it has is fairly small. A number of options have been looked at in the last few weeks ranging from various netbooks (Eeepc 701 and it’s followers) as well as nano and pico itx systems. But the unit that caught my eye was the Fit-PC. Claiming a 3-5W drain and wifi really looks like a potential for low or even off grid monitoring. The units are fairly pricy so depending on the success of the SDR lite project the hole station can be put into a small box