Hello again

Fifteen years later and I finally post something new 😀

I am keeping this blog as an archive and have started a new one for my current activities.  Please take a look here.

New Antenna

A combination of work and other priorities at home has kept me mostly off the air for the last few months. But with some free time over Christmas, I have finally got round to sorting out a new (albeit temporary) antenna.

My old doublet had already lost part of one of its arms many months ago - the wire had been rubbing against a guttering downpipe when it was windy. I had made a tempoarary repair at the time, but then a couple of weeks ago, the same arm came apart at the centre insulator - metal fatigue, I guess.

We may be having some building work done at the back to the house, which could mean I will have to move my shack. So I didn't want to spend a lot of time repairing the doublet which might become redundant in a few months.

Instead, I have rigged up a simple end-fed wire - from the shack up to the eaves, along the back of the house, then down to the back wall of the garden. I guess it is about 30m long in total. Seems to tune up OK on 30, 20 and 17 meters. I'll do some more testing over the weekend.

M0DHP lite

So here is the new lightweight M0DHP station. Satellite gear gone. Old PC gone. Linux box nestles neatly under the monitor. K1EL keyer added to the mix.

DXCC and Linux

The Gibraltar QSL card took me to 100, and then I got to 101 - I can't remember which country it was, though :-) So, off they went to Ian G0KRL (the ARRL checker) and they were all OK. Just waiting for the certificate now.

Meanwhile, I have now got the Aleutia E2 up and running with the USB SignaLink. Made my first PSK31 QSOs with the new setup using fldigi. And CQRLOG is working great, too. I'll get some photos and post them soon.

Finally, I have taken down my satellite installation. Time to focus on CW DXCC.

Spring clean - and one step closer to DXCC

Not much operating in the last couple of months, but a few changes in hand. With a potential move of my radio stuff to another part of the house, and the failure of my AZ - EL rotator, I took the decision to give up satellite operation for now, and concentrate on getting my DXCC CW.

So I have cleared some of my radio gear to "archive" (in other words, the garage) and given my operating desk a much needed clear up.

My old PC had been ill for some time; the disk controller on the motherboard was giving frequent errors. So, rather than invest in a new Windows PC, I have switched to Linux and invested in a small, low power PC - the Aleutia E2. I think I'm settling on CQRLOG as my logging program, and I will use Fldigi for digital modes once I have upgraded to a USB version of my existing SignaLink interfaces.

I will post some pictures of the new setup once I am back from a business trip.

In the midst of all this, I got a batch of cards from the RSGB QSL Bureau. Among them was a card from ON5MRT when he was operating from Gibraltar. I need to double check my log, but I think that makes DXCC :-)

Botheration

What happens if you leave a piece of machinery outdoors, don't use it for several months and don't oil it from time to time? That's right - it seizes up. Which is exactly what has happened to the linear actuator on my amateur satellite elevator.

And in trying to free it, I think I have burned out its motor. I should know better :-(

I have manually positioned it to about 30 degree elevation (and disconnected it from its control system) and will see what I can work like that. In particular, I'm trying to download the telemetry from Delfi-C3.

To fix the elevator, I suspect I will need to replace the actuator, which is not cheap and is a big job. Not sure when I will be able to do it.

PIC-based speed controller (3)

I can't claim much originality for the design of the speed controller (neither the hardware nor the software). Here are some of the sites on which I found useful source material - many thanks to their authors.

The Swordfish compiler site runs a wiki that includes user generated code modules, including a PWM module from David Barker. And I learned a lot from Chuck McManis's pages about servo speed controllers.

Before getting into the complexities of programming PWM, I got up to speed with the basics thanks to tutorials and articles at Gooligum Electronics and Pete Griffith's site.

Lastly, I downloaded the 18F1320 reference manual and the PICkit utility (for loading the binary code generated by the Swordfish compiler into the PIC in the Junebug) from Microchip.

If you would like to see the source code I ended up with, here it is.

PIC-based speed controller (2)

The advantage of using a PIC for a project like this is that the component count is kept low. Take a look at the circuit diagram to see what I mean :-)


The 15V DC power supply is regulated down to 12V to give a constant peak voltage for the PWM output to the motor. The 12V is further regulated down to 5V for the PIC. Also on the left of the diagram are the three LEDs with series resistors, and the reset button for the PIC.

On the right of the diagram, the speed control button connects straight to one of the PIC I/O pins. The PWM output waveform goes to an opto-isolator and then a driver transistor.

In the actual build, I also added a diode in series with the 15V power supply to protect against accidentally reversing the connections.

Having designed the circuit using PCB123 Schematic, I worked out the stripboard layout using VeeCAD. Here is the layout.


I'll put up another post soon with details on the sources I drew on for writing the software.

PIC-based speed controller (1)

Let me start with an outside view of the speed controller and explain what it does. It converts a 15V DC power supply into a 12V constant voltage, pulse width modulated power output for a DC motor. There are three pre-defined speed settings in addition to "off". And there is a watchdog timer, so if the motor is left running for 15 minutes, the controller automatically turns it off.

The user can cycle the speed setting between off - 1 - 2 - 3 - 2 - 1 - off - 1 - etc by pressing the black button. The three LEDs light up according to what speed is set.

After pressing the button, the speed gradually changes to the next setting; this transition takes three seconds. During the three seconds, the relevant LED flashes repeatedly before going steady when the speed has reached the new level.

The red button is emergency stop. It actually resets the PIC and hence immediately sets the speed to "off".


I got most of the components from Rapid Online. This included some very neat sprung terminals for connecting the power input and motor output.

The circuit is built on stripboard. More details on the circuit design and PIC program in my next post.

Warming up the soldering iron

It has been over a year since I last posted anything radio or construction related. I have not been completely inactive in that time. I am up to 97 countries worked and confirmed for DXCC, with an increasing proportion of those on CW. But I have not built anything for a long time - until the last few weeks. And while it is electronic, it is actually nothing to do with radio.

The "it" is a PIC-based speed controller for a cable car that is going to be part of my son's model railway. The railway is still far from complete, but we bought a motorised cable car (made by Brawa) and recently tested it out. It will be a great addition to the railway, but I realised that accidentally leaving it running for a long period would not do the little DC motor any good.

So I started looking around for timer switches that would cut the power after, say, ten or fifteen minutes if we had not turned it off ourselves first. I posted a message on the G-QRP mailing list and someone (I'm sorry to say I can't remember who it was) suggested using a PIC.

I had never used a PIC before, but I do have a background in computer programming and hardware design, so it sounded like an interesting option. After a bit of research, I bought the Junebug prototyping / programming board from blueroomelectronics and downloaded the Swordfish BASIC compiler. I was soon flashing lights on the Junebug, but it took a bit more work to get a speed controller up and running. I'll post more details soon.

FO-29 SK? And remote rig control

Lots of emails on the AMSAT-BB mailing list over the last couple of days reporting that FO-29 has stopped working. Fingers crossed that JARL can recover it, otherwise my transatlantic QSO objective may be in question. I'll need to check whether VO-52 is simultaneously visible to the UK and USA or Canada.

On a more positive note, I discovered two things this week. Ham Radio Deluxe, which (among other things) can CAT control a rig, can be launched as an XP service. You can then control HRD in client-server mode from another copy running on a different PC. I also found out that Skype can be set up to take input from line input on a sound card. So, I have been able to tune my FT-847 on HF from my laptop and listen to the received audio, using a Skype call from my shack PC to my laptop.