Tuesday, 24 December 2013

A (Christmas) Magic Smoke Event . . .

I have recently been giving one of my "old ladies" in the guise of my 1982 vintage FT-101ZD Mk3 a "run out", promoting it to "main station rig" status for a few days despite the fact that I am aware that it is still in far from perfect working order.

It's basically a nice set, so that was no major sacrifice.

However, after the radio had been on for a few hours I suddenly started to get a distinct smell of "something" from it. I've smelt very many electronic faults in my time, but this one seemed rather to smell of a pan on the stove burning dry, but I quickly realised that there was no pan on the stove in the kitchen, and that the smell was indeed coming from my '101.

I removed the power and found a flashlight so I could investigate the cause, and spotted a little plume of smoke emanating from the left hand rear of the rig, and I also noticed that this corner of the rig seemed to be rather warmer than normal.

Straight away I disconnected all the external cabling, and, having allowed a reasonable time for the internal high tension power supply to discharge, I removed the top cover thinking that the sooner I could get at the innards, the more likely I was to identify the source of the problem.

Thus I homed in on the "Rectifier B" board and quickly spotted a rather distressed looking electrolytic capacitor which also seemed to be unusually warm to the touch.

Rectifier B Board in situ - PB-1968B

Now it may be recalled that this radio, bought originally as a “spares or repair” item from EBay, has had a chequered history having done questionable service as a high powered and illegal CB rig. It had no doubt been abused, quite possibly by someone less educated in the finer arts of the tuning and conservation of valve/hybrid rigs, this abuse being most keenly felt by the power supply stages. I had already rebuilt the “Rectifier A” board which had expired completely, and it now appears that I should have paid rather more attention to the “Rectifier B” board, which supplies screen and grid bias supplies to the output stages.

My own fault and hopefully any collateral damage will be minimal.   Looking on the bright side, as one of my “Twitterati” so nicely put it, at least it was “Christmas Magic Smoke”!

Saturday, 21 December 2013

Microsoft Windows 7 - Gain without much Pain . . .

With the impending end of Microsoft’s support for their venerable and very successful Windows XP, I had been wrestling with the relative benefits of either “upgrading” my existing main desktop PC to Windows 7, or replacing it entirely, with the risk of having to put up with the almost universally reviled Windows 8.

I had been using Windows 7 on a  borrowed PC for some time and had become relatively comfortable with that environment, and so decided to take the plunge and go down the “upgrade” route with my 7-year old, reasonably specced (for its time) machine.

I purchased a copy of Windows 7 Home Premium from a seemingly reputable (according to the feedback) EBay supplier  and a brand new hard drive from EBuyer.com ( the thinking there being that there was an easy route back if the Windows 7 installation proved to be a disaster).

I have to say that the whole business went surprisingly well right from the initial minor surgery to replace the primary hard drive on my PC, which even included a vacuum out of the dust, cobwebs and general detritus which had accumulated in the last 12 months since I last had the machine apart.

The Windows 7 installation itself went very smoothly, the most anxious moments being those during which I waited with baited breath to see if my 25-digit licence code would be accepted (it was!).

I am not a player of games, apart from the “normal secretarial duties” of EMails, web surfing and writing documents, my machine spends most of its time running fairly esoteric Audio Spectrum Analysis DSP software associated with my hobby of recording “radio meteors” so the amount of software I had to re-install was relatively small.   Everything I installed worked pretty well without any problems and here I am a day later with a machine with a completely new operating system installed running every program I use regularly, consequently I am as “Pleased as Punch”.

The only downside is that of the new Microsoft Office 2013 which I have had “in stash” for a while ready to be installed on a Windows 7 (or later) machine.   This has appears to have been designed to have a “Windows 8” look about it, and frankly it’s horrible to look at.  I felt obliged to install this heavyweight package due to it (a) being cheap due to an arrangement my employer has with Microsoft, and (b) there is no built-in EMail client in Windows 7.  

I could of course opted for something like OpenOffice with Mozilla Thunderbird, but I had the Office install disk already.   Maybe more on that later, but at the moment I am struggling to find any nice words about Office 2013, but I should probably give it more time before I put virtual pen to paper!  It appears to work fine, but it just looks DREADFUL.   That’s a great shame as one of Windows 7‘s greatest appeals is that it “looks nice”, to me, anyway . . .

Sunday, 12 May 2013

Icelandic Meteor Reflections - Channel E4

The purchase late in 2012 of a "FunCubeDongle Pro+" opened up a new world to me - those parts of the "Low VHF" spectrum away from the amateur bands, or to be more accurate, away from the amateur 6metre (50MHz) band.

Very soon I homed in on a "new" target for meteor reception of the Skalafell TV transmitter in Iceland. This transmitter is allegedly due for closure at some point in 2013 as part of the Europe-wide "Digital Switchover" so I was naturally keen to make use of this before the big switch-off. I quickly found that it was an excellent target for meteor reflection reception, being at more or less the optimum distance away, high power (presumably) and on the air (as it turned out) 24/7.

This year's Eta Aquarid meteor shower coincided with a public holiday which meant that I wasn't working and therefore was able to pay pretty close attention to the "goings on" on all my meteor targets, and it wasn't really a surprise when I started to get some pretty impressive results on this channel (E4 - 62.25MHz).

 However, what was a surprise was the realisation that I was receiving TWO signals, the second and surprise one being a few hundred Hz below the main one.

What was really interesting to me was the similarity in some ways and difference in others between the characteristics of the received signals.

There were many occasions when coincident reflections were received, and others when there were completely separate reflections.

Similarity suggests that the two sources are relatively close together, and difference suggests that they are not _that_ close.

At the moment I am working on the assumption that they are both from Iceland, but possible in geographically separate parts of that country.

This has been further supported by a more "normal" spell of observation today when meteor activity is at a "normal" level, and, with this being early summer, some tantalising hints of more exotic propagation modes, namely "Sporadic-E". Again I have seen many examples of "co-incident" reflections (Sporadic-E ones seem to be co-incident in general), and non co-incident ones.

According to the "G0CHE" Band I TV information web page there are indeed two (suspected) Icelandic TV transmitters on channel E4, though the frequencies quoted on that site don't quite stack up with my own observations, unless the "new" signal is really Skalafell, and the one I have been referring to as Skalafell is actually Gagnheiði.

Any help in unraveling this mystery would be appreciated!

Sunday, 5 May 2013

Adlestrop (a short poem by Edward Thomas)

People who have the dubious honour of knowing me personally know that I am most certainly not an "arty" kind of person.

OK I play music semi-professionally in a "ceilidh band", and have an eclectic taste in music, well I think I have anyway,  but other forms of "high art"  (visual and the written word) are a mystery to me.   My taste seems to be very unsophisticated in comparison with that of others.

I mean, a picture should _look_ like something, shouldn't it?  I'm an engineer by profession, I believe in Ohm's Law!

However Damien Hirst makes far more money than I do, so I guess I'm the one in the wrong.

But perhaps by way of proof that I am not a complete Philistine, here is my favourite poem.

It's very short  but it evokes such imagery in my imagination that it astounds me in its brevity and seeming simplicity.  I never tire of reading it.


Yes, I remember Adlestrop --
The name, because one afternoon
Of heat the express-train drew up there
Unwontedly. It was late June.

The steam hissed. Someone cleared his throat.
No one left and no one came
On the bare platform. What I saw
Was Adlestrop -- only the name

And willows, willow-herb, and grass,
And meadowsweet, and haycocks dry,
No whit less still and lonely fair
Than the high cloudlets in the sky.

And for that minute a blackbird sang
Close by, and round him, mistier,
Farther and farther, all the birds
Of Oxfordshire and Gloucestershire.

Friday, 3 May 2013

High Altitude Ballooning

For a little while now I’ve been fascinated by the hobby of “High Altitude Ballooning“.
It’s such a short while that I can’t yet claim to be an expert in that subject, but what I have seen has really sparked my interest and imagination.

I stumbled on a page on the  "Raspberry Pi" web site, and it turned out that the "Pi" and ballooning have been bedfellows for quite a while.    Furthermore it seems that the BBC's James May (Man Lab) and Channel 5's Gadget Show  have have featured balloons, but as someone who rarely watches TV (even more rarely now Time Team has been axed!), this has only recently come to my attention.

This particular activity, and the background to it appears to pull together a number of disciplines, and it’s the amalgamation of these which has really got me excited.

Once I discovered, almost by chance that the telemetry transmitter from HABs (High Altitude Balloons) could be received at my modest radio station from a distance of 200+ miles I realised I could participate in this activity, even if I never actually went near a balloon.

Even more exciting was the realisation that many of the participants in this activity sre relatively young people.    I've long felt that it is high time that the younger element of our population took up the baton of technical innovation and put those of us of the “older generation” firmly in our place.

It’s not exclusively the dominion of the young, but there appear to be proportionally more of the younger generation taking part than say in “vanilla” Amateur Radio.


Here are a few web links to enlighten you further, if you are interested :-

UK High Altitude Societywww.ukhas.org.uk

SpaceNear Online Tracker (Google Maps based application) -  spacenear.us/tracker
Note that ballooning is popular on the Continent as well as in the UK, especially in Poland.

StratoDean – a fabulous blog maintained by participants from the Forest of Deanwww.stratodean.co.uk

Balloon flights tend to take place at weekends when the weather is favourable.  “Weather” doesn’t just mean what the weather is like at ground level, but also what the winds are doing in the stratosphere as these balloons usually achieve an altitude of over 30,000 metres (yes, 30km!), and the participants aren’t too keen on flight predictions which end in either the sea or in foreign countries!

 The above graph lifted from the spacenear.us online tracking application shows the flight profile of a recent flight and clearly shows what is likely to be achieved in terms of altitude and duration.

A flight in the south of England becomes audible to my station in the north of England once it gets to around 10km in altitude, and the telemetry  transmissions are generally decodable throughout this phase of the flight.

Telemetry is transmitted from the payload using small proprietary low power transmitters which happen to use part of the amateur "70cm" band, which is basically where we radio amateurs come in - many of us have high specification equipment and aerials capable of receiving these transmissions.   In my case I use my trusty Diamond dual band (2m/70cm) co-linear and my FunCubeDongle ProPlus SDR, see below.

The above picture is a composite (ie more than one image has been stitched together to make a single image) screen grab of  a “Spectrum Laboratory” screen and shows in graphical form the strength of the signal from the “Stratodean1″ flight from around 0945 UTC until about 11:30 UTC when the signal was finally lost as the payload descended under its parachute.  NOTE: The sudden “steps” in the display were caused by me adjusting my receiver to get the signal “centered” in the passband of the display, and were not caused by a problem with the payload telemetry transmitter!

Just to give you an idea of how remarkable radio transmission are above 10km, note that the transmitter power is 10mW, and the aerial on the payload is a simple ground plane affair made by using a length of stripped back coaxial cable and drinking straws!   See the StratoDean web site for more information about this and other technical details about the payload.

The screen grab below shows the flight profile for StratodeanOne and I've marked it up to highlight the part of the flight I was able to receive in Penrith (IO84 square).