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!

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.

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.

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?

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.

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:

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.

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.