28 December, 2012

Half a year of APRS temperature monitoring

My APRS-based temperature monitor has now worked flawlessly for half a year. APRS stands for Automatic Packet Reporting System so it can send much more than temperature data, the chief usage is really for GPS position reports.

But I just needed a temperature monitor and here are the readings for December. As one can see, there were no days with temperature above freezing. At 800 m elevation in the mountains of Telemark in Norway, this is not unexpected for this time of year and makes for good skiing!

I use a Quanzheng TG-25AT handheld with a quarter-wave whip antenna on 144.800 MHz. Its signals reach the LD3GT digipeater at 1845 m above sea level. Although I don't have direct line of sight, the low power (1 Watt) setting is adequate as the distance is only 10 km. The APRS-beacon is an OpenTracker USB set up for transmission every 15 minutes. An external DS18S20 temperature sensor which measures the outside temperature is connected to the 1-Wire® bus of the OpenTracker USB.

Thanks to the infrastructure providers: The Tønsberg group of NRRL (LA1T) who operate the LD3GT digipeater, probably the one with the largest coverage in Southern Norway (Gaustadtoppen). Thanks also to the various operators who receive packets from LD3GT and pass them on to the internet, and thanks to aprs.fi for processing and displaying the data on their excellent web site!

25 November, 2012

The most interesting contact in the CQ WW Contest

Sometimes looking up remote stations on QRZ.com or other sites gives a glimpse of the person behind the callsign. I did this for the Chinese station BY5CD which I contacted on 40 m during the CQ Worldwide contest this weekend.

It turned out to be a club station called "YinZhou Middle School Amateur Radio Club Station" which is located just south of Shanghai.

It is interesting to consider the age of the operators as one can see from the picture. More pictures and some information can be found on their QRZ.com website. With this many young people entering ham radio in China, maybe we will see more stations there in the future. The number of stations is unreasonably low compared to the enormous population of China.

And the most interesting signal was that of GM5X on 21 MHz at 1207 UTC on 25. November. It had a distinct echo which seems to indicate that the signal travelled both on the direct path of about 800 km and the long path of about 39200 km.

The image shows "GM5X GM5X Test". The long path signal seems to fade in and out as there is much less of it in the last part, the word "test", than in the second "GM5X".

18 November, 2012

F/LA3ZA on Long Delayed Echoes

Laurent, F6GOX, who is one of the primary forces behind the ARP, Radio-Club de Paris, has written a nice little French-language presentation of me since I am a former member of the club. It also includes my interest in Long Delayed Echos (LDE).

Here he also talks about the presentation I gave for the Paris club of radio amateurs on 18 March 2009 on this subject during my year-long stay in Paris. That was a very nice evening which I remember with pleasure.

I also talked then about the interest that the French general Gustave Ferrié (1868 - 1932) took in this phenomenon (The link is in French, but read about Ferrié here in the English Wikipedia). There were French studies of LDEs in Indochina, Senegal, and Mauretania, French territories at the time, which he played a major role in.

Merci Laurent!

17 November, 2012

Visiting 409shop in Hong Kong

A stop-over on my way from Sydney to Oslo gave me the opportunity today to visit Apliu street in Hong Kong. This is where all the electronics products are found. As I had purchased a Baofeng UV-5R from them before it was fun to stop by the 409shop as well. Their address is on their web site, and the word "showroom" really made me expect something larger than what I found. It turns out to be just one small store among hundreds of others in this street.

I bought a handheld frequency counter, Yaege FC-1, and a better antenna, Nagoya NA-666,  for the UV-5R and got a good deal - I like to think that it is because I presented myself as a previous internet customer.

On the other side of the street there was another store with communications equipment as well, Yee Fu Technology Shop, where I bought a 13.8V/20 A switch mode power supply, HK Products Electronics SPS-200MA.

It even had a noise-offset control which I have come to appreciate in my other power supply, the Alinco DM-330MV. It is particularly nice to have on 160 m. How they avoid Alinco's pending patent on this feature is something I don't know. There seems to be several other supplies on the market with this feature also, such as the Watson Power-Mite-NF (NF for Noise offset Function), so maybe Alinco's patent application hasn't been granted?

23 October, 2012

A Useless Machine with delay and howl

The useless machine or ultimate machine originates from Claude Shannon, the scientist who figured out how to find the channel capacity in a communications system. I bought the basic machine as a kit from Solarbotics.

But then I added a few features:
  • A delay circuit that makes it look more alive as it gives the impression of doing some thinking before it responds to the switch.
  • Sound that varies with how open the lid is and the amount of light that hits the photosensitive resistor. It was inspired by the design of the Growl and Scream Altoids of FightCube.
  • A couple of LEDs, a red one when it opens and a blue one when it closes.
The circuits were built on small pieces of veroboard and the circuit diagram can be downloaded from here. In retrospect I'm not completely happy with the sound, it could have growled and screamed even more, but then how much effort can one really justify putting into a project which is - useless - anyway?

20 September, 2012

My first 24 hours on WSPR

My first beacon on 30 m, a free-running Ultimate QRSS kit (no GPS) has now been running for a full 24 hours using the Weak Signal Propagation Reporter (WSPR) mode. The figure comes from the WSPRnet page.

With an output power of about 150 mW to an 80 m horizontal loop it has not been possible to reach beyond Europe so far. Perhaps this will happen in the future with better conditions and/or with some more output power.

Added 26.9.2012: I made it for the first time across the Atlantic!
Timestamp           Call       MHz         SNR Drift  Grid      Pwr Reporter   RGrid      km      az
2012-09-26 00:50, LA3ZA, 10.140262, -26,   -2,   JO59fu, 0.2, WB2EEE, FN21xh, 5852, 290

16 September, 2012

Altoids Projects

Press image for magnification
I like to build small electronics projects and like many others I have found the small Altoids tins to be excellent enclosures. 

These tins are inexpensive, well shielded, easy to work with, and least but not least they enable you to make experimental circuits that are sturdy enough that they can be reused later.

Pictured here is a collection of projects I have built over the years with the hope that  they may inspire others.

04 September, 2012

Noisy Designer Lamp

Herstal pendant lamp,
type 06
Some years ago I had this annoying noise that made listening for weak signals on several of the shortwave radio bands virtually impossible. In the end I was finally able to track down the noise source: Our beautiful Danish Herstal designer lamps in the kitchen. Actually it wasn't the lamps themselves, but the dimmable switch mode power supply that came with them.

After some years of always having to remember to turn them off, in the end I just replaced the original noisy dimmer with a fixed voltage, noiseless, electronic transformer and inserted lower wattage 12 V light bulbs in the two lamps.

The original dimmer came in its own nice conical designer housing and inside one finds a more ordinary plastic housing. And of course it is marked with the CE mark, thus indicating that it should be fine with respect to noise.

21 August, 2012

Fixing my Lithuanian oscilloscope

I visited Riga, Latvia with a youth group which we as a family were involved with in 1992, and there I stumbled upon a Soviet oscilloscope in a department store. It was from the neighboring country, Lithuania, and was manufactured in Vilnius, the capital. The markings say what I guess means "Made in the Soviet Union". At least it says CCCP in the upper right-hand corner. I remember these letters very well as all Soviet athletes used to have them on their backs.

The oscilloscope came with full documentation, even with a bilingual manual. I had grown fond of this oscilloscope as it was lightweight and simple to use once I had learned what the Russian markings meant. It is a typical instrument for TV-repair with a 7 MHz bandwidth.

Now after 20 years, I was therefore very sad when it malfunctioned. This was the time to test if the manual was helpful or not. The symptom was that the beam no longer could span the whole screen in the X-direction. Even with the Horizontal positioning all the way to the left one could barely see the beam.

I opened the bilingual manual only to discover that the two languages were Russian and Lithuanian!

16 August, 2012

Transformerless tube power supply

In 2012 bulky power transformers that work directly from the power grid at 50/60 Hz have mostly disappeared. My objective here is to modernize the power supply for a one-tube transmitter in the same way.

The circuit is based on an electronic transformer for LED or halogen lamps. Electronic transformers usually have a minimum power rating, below which they will not start. This one can tolerate a lower load than most and gives out 12 Volts for a load from less than 10 W and up to 60 W.

07 August, 2012

Nostalgia from LA3ZA in 1949

I wasn't even born when this LA3ZA QSL-card was issued in 1949. This is because I am second generation LA3ZA after my father. When the callsign was reissued to me in 2001 it had been inactive for 40 years or so.

I still have the Hallicrafters S40A receiver which my father used with a 2 W input homemade tube transmitter. The S40A (image below) was what introduced me to shortwave listening during the good conditions of the solar peak in the late sixties, despite its mediocre performance I would say.

01 August, 2012

Vertical antenna on a turf roof

A vertical wire antenna based on a MFJ-1904H 6.7 m (22 feet) telescopic fiberglass pole as shown here is easily tuneable for all bands from 40 m to 10 m. Here it is placed on top of a turf (sod) roof with quarter wave radials for all the 7 bands going to each of the two sides sloping down as they follow the contour of the roof. The antenna seems to work satisfactorily at least on the 30, 20, and 17 m bands which I have been able to test so far.

A turf roof is a traditional Scandinavian type of green roof covered with grass. It dates back to the Viking age and before. In modern times it has seen a renaissance in e.g. mountain cabins.

But how does the turf affect the antenna or to pose the question more precisely: Can it be used to improve the ground plane and the antenna's performance?

05 July, 2012

Vintage Tektronix oscilloscopes

I first encountered this generation of Tektronix oscilloscopes in my first job at the Electronics Lab of SINTEF, Trondheim, Norway in 1978. Already at that time the main use for them was as heaters in the offices. That is, only if you wanted to work in the break between Christmas and New Year when the central heating was turned down.

Since then I have come across the two oscilloscopes shown here, and the collector (or is it hoarder?) in me has not been able to say no to them. They are really advanced for their time: regulated power supplies with tubes, ceramic stand-offs and lots and lots of tubes.

The  oscilloscopes are 541A and 543, from 1959 and 1964 respectively, it seems. The plug-in units are 1A1, L, M, and 53/54K plus the cart. The 1A1 actually seems even to have FET-transistors, not only tubes like the others. The units work, but how well they work I am not sure about as they have been in storage for the last 5-10 years.

25 June, 2012

The 10 biggest lies in audio

Quad II Tube amplifier. (Wikipedia Commons, user Harumphy)
In the fall of 2000 The Audio Critic had an article listing the 10 biggest lies in audio.

The article is well worth reading even today although the scene has changed a little since it was written. It for sure makes you think.

Peter Aczel's points were:

09 June, 2012

Medium delayed echoes

Medium Delayed Echoes or Magnetospherically Ducted Echoes (both MDE) are radio echoes delayed from 0.14-0.3 seconds. They represent a subset of Long Delayed Echoes (LDE) and is the only one of the five LDE effects discussed in "The Five Most Likely Explanations for Long Delayed Echoes" which is fairly well understood.

Here is a fascinating report of such echoes from G3ZRJ. His report is different from those of many others in two unique and very interesting ways.

02 June, 2012

More long delayed echoes

4.5 metre high UK acoustic mirror used as early warning system
during WW1. Not so relevant for Long Delayed Echos, but something
which definitely reflects well. Wikipedia Commons, Paul Glazzard
The mystery of Long delayed echoes is still without a scientific solution. With that I mean an explanation in terms of an effect which is testable, i.e. where one can predict the value of the delay and under what conditions it occurs.

It is likely that there isn't just one explanation, but several. I found it helpful some years ago to list all 15 possible hypotheses and then narrow them down to The Five Most Likely Explanations for Long Delayed Echoes. This list is now being referenced on the RSGB site for Long-delayed echoes (LDE) as well as in the Wikipedia article on the subject.

In this blog post there are examples of multisecond echoes on 21 and 27 MHz.

20 May, 2012

Will I ever complete "Worked All States"?

Here's my map of confirmed US states as it has slowly been filling over the last 10 years. 41 states have been confirmed on CW on Logbook of the World, while 9 are still missing.
In recent years progress has been very slow so I don't see my WAS being finished any time soon. Perhaps there is some resource on the web that could assist me with arrangements for the remaining states, or even some readers in these states who would help me?

09 May, 2012

Unusual HF Propagation Phenomena

Earthrise from Apollo 8 (NASA)
My blog has just been updated by migrating posts from my old web site containing a collection of audio samples from unusual HF propagation phenomena. They range from round-the-world propagation (delay 138 ms) to ducted transmission in the magnetosphere (delay ~140-300 ms) ending with moonbounced 7 MHz signals (delay 2.39 sec).

The posts are:

05 May, 2012

Passive Crossfeed for iPhone

Some records just have too much stereo separation. This makes them kind of artificial to listen to with earplugs or headphones as the sound in the two ears is too different. This is where a crossfeed circuit has a role to play as it is designed to mimic the blending of the two channels that takes place when listening through loudspeakers.

As the head is smaller relative to the wavelength at lower frequencies than at higher, the shadowing is also smaller. Therefore there should be more blending of right and left below 1 kHz than at higher frequencies.

01 May, 2012

Reliable auto-detect for keyer for Elecraft K2

The Elecraft K2 has an autodetect feature for the keyer input. When enabled, and when the DASH and the DOT lines are keyed at exactly the same instant in time, the K2 will detect that this is a hand key or an external keyer. I and several other K2 owners have however experienced erratic action of the autodetect with seemingly random keying.

My problem only occurred when keying was done from an external keyer. This could happen when keying from e.g. the WinKeyer.

24 April, 2012

Incredible projects based on 7400 logic

Last fall there was a competition at DangerousPrototypes with many interesting entries based on the 7400 logic gate family. The ancestry of these circuits goes back to the 60's and early 70's, but they are still popular. I have picked out some of the ham radio related entries here.

They said "The Open 7400 Logic Competition brings awareness to open hardware and software, and fosters understanding of the building blocks of modern integrated circuits. What can you build with logic chips?"

I think the most interesting and inspiring entries were:

22 April, 2012

Simple IKEA transmit indicator

IKEA Oleby automatic wardrobe light with passive
infrared sensor upper right and four LEDs in the center.
Passive Infrared (PIR) detectors have the bad habit of being sensitive to radio frequency (RF) radiation. This can be a nuisance for neighbors of radio amateurs. But we can use this property to our advantage as this makes them suitable for transmit indicators next to a feedline.

The IKEA motion activated LED sensor light, which one can get for a few dollars or euros, turns out to be quite simple to hack for this purpose. You can only buy them in pairs so the other one can be put to use in the darkest wardrobe you have.

09 April, 2012

Whatever happened to the 1 Volt QRP Transceivers?

Output stage of the 1 Volt DL2AVH transmitter
(from http://www.lichtnetzwerk.de/1volttxvr_dkumentation.pdf)
I am intrigued by minimalist transceiver designs like the Pixie 2 which I built some years ago. Therefore the "1 VOLT Challenge" from Dayton 2000 is also something I wish I knew more about. It had these winners:

1. Duncan Walters, G4DFV - The HAMEOBA - A 100 mW Single Cell CW Transceiver (30m)
2. (tied) Helmut Siefert, DL2AVH - A 30m 1V QRP transceiver
2. (tied) Charles Fletcher, G3DXZ - An 80m CW QSK Transceiver
4. Jim Roberts, NC9H - A 20m 1.5V Transceiver

Now, what happened to these designs? I'll try to figure it out from sources on the web.

03 April, 2012

A history lesson from call signs

World empires and colonies in 1914,
also at the time of the 1. Int. Radiotelegraphic Convention.
Source Wikipedia Commons, user Andrew0921
There's a lot of history to read out from amateur radio call signs. Being interested in history as well as amateur radio I found that for some countries you can actually figure out which time period it got independence just by looking at the prefixes of the call sign. But on the other hand the history of the international conferences and the call sign allocations is as complex as politics can be so this short blog post can only scratch the surface of this complicated topic.

I have always been envious of those radio amateurs who have a call sign starting with a letter that reflects their country's name. This seems to be the privilege of big and powerful nations, or countries that were just lucky in having names that didn't overlap too much with those of other nations. Among the 1913 call signs one can find:

04 January, 2012

CQ DX Marathon and 2011 Activity

I just submitted data for all my radio contacts for 2011 to CQ DX Marathon. My log program is UcxLog by DL7UCX and I started by exporting the ADIF-log and then analyzing it with the recommended analysis program by AD1C.

In the process of doing the conversation I also happened to find the Contact Map tool from NS6T which generated this map from my 2000+ contacts in 2011. What it shows below it not so surprising - from my location in the south of Norway it is easiest to work Europe, Russia and the East Coast of the US, but it is nice anyway.
2011 contacts from LA3ZA, open in separate window for larger map.
My CQ DX Marathon result was 167 countries (165 real DXCC countries), 35 zones giving a total of 202 points which is a result I was very happy with. It was actually my highest country count in a single year since I got my license in 2001. Much of it must be attributed to the renewed activity of the sun last year which gave a lot of new opportunities on the 10 m band. All countries except one are CW (morse) contacts with a 100 W Elecraft K3. Antennas are a 75 m long horizontal loop for the lower bands up to and including 21 MHz, and a 5 m half wave wire vertical for 24 and 28 MHz. The length of the wire loop exceeds that for the Formula Class, so I had to submit my score in the Unlimited Class.

Now I am only looking for a software tool which can analyze my ADIF-file for US states and Russian oblasts, but so far I haven't been able to find any.