Radio and rails...

I am making a better effort at picking up the SAQ broadcast due on the 1st of December. I now have a VLF mini whip (no idea where it came from now!) up in the loft fed via a bias-tee and connected to a Heros VLF converter which takes 0 to 500kHz and converts it to 4,000 to 4,500kHz. Although the loft is a poor location for this it is a lot better than in the shack. the Heros is connected to an RSPdx on it's BNC port and this is connected to the Linux PC which runs SDRconnect as a server. Reception is via SDRconnect on the Mac. So far, so good, I can see the MSF and DCF77 time signals on 60kHz and 70.5kHz respectively plus a ferw other peaks, at least some of which correspond with known transmitters. Getting the settings right is a fiddle. The above photo has the base set low and the red line is where SAQ should be. But there is quite a rolloff there so hopefully the signal will be sufficiently strong to receive. The antenna is supposed to work down to 5kHz and the Heros is specified as <5 to 500kHz.

Something leaks here, not always, just sometimes when the autotuner has an issue. RF gets into the Bluetooth stuff in the Mac and it goes mad. The net result is the cursor moves very sporadically making it very hard to maneuver the cursor. In the past I have resorted to rebooting the Mac - switching Bluetooth off and on is a no-go because I only have a Bluetooth keyboard and mouse so I'd not be able to turn it back on. Helpfully, the current MacOS knows this and won't let me turn it off anyway. So I reboot. However, yesterday I had the other systems turned on with MMSSTV and wsjt-x running on them so rebooting the Mac would have been rather awkward given I use Barrier to control the other systems via the Mac. So a bit of searching turned up a simple console (terminal) command 'sudo pkill bluetoothd' which did the trick. Apple has info at https://discussions.apple.com/docs/DOC-250003311 One to remember but YMMV of course... also, serves me right for letting RF in the shack in the first place.

I managed one 70cm FT8 QSO today. I had the TS2000X on 70cm randomly and answered a CQ. That was around 50 miles out to the southwest across the Pennines, so not so bad for my loft 70cm Big Wheel and with the rig set to 10W. A little later I put out a CQ, no replies but it did indicate I was heard in Wales at 78 miles and Northern Ireland at 179 miles.

You know the saying, a man with a watch knows the time but a man with two watches has no clue. Well, my GPS clock plus 10MHz source has decided it no longer wants to be a clock. It was a nice idea, came as a kit of parts from three sources and worked well up to a point. But the GPS module always seemed a little deaf. I had it connected to one of those little magnetic pucks but it struggled, often loosing all sight of any satellites. I tried it on an external antenna (sat on the windowsill) and on the puck placed outside with no difference. With a splitter inline a Leo Bodnar unit was happy so I had to assume the antenna was fine. Anyway, it has spent all day with no satellites in view whereas the QRP Labs clock is fine as is the NPT server. So it has been switched off and assigned to the 'box of abandoned projects' where it resides, alone. (edit: that one is now outside in the workshop with a small GPS antenna on the workshop roof and is working just fine - except the LCD is very sluggish with…

Another of my hobbies, if you can call it that is that I volunteer at a heritage railway in the Signal and Telegraph (S&T) department. We maintain the signalling along the 4.5 mile railway which includes three signal boxes and numerous signals, points and telephones. Occasionally I get homework. This week it is working out the resistance needed to drop the voltage across the track at one point to a level suitable to power a relay. This is for a track circuit, in the case in question across a set of points. With the track circuits we use the section of track concerned, which is isolated from the rest of the railway by insulated block joints separating the bits of rail, power is fed to the rails at one end and a relay is connected at the other. The voltage needs to be sufficient to keep the relay up and this indicates that there is no train on that section of rail. When a train is on that track the voltage is shorted out across the wheels and the relay drops to indicate the presence of a train. The relay concerned is similar to the one shown below and has…