Polar Research vessel Oden gets a ZachTek WSPR transmitter.

Updated: Jul 4, 2019

WSPR is a great way to explore and test a wide range of stuff in our wonderful radio hobby.

Although I guess most of us use WSPR casually with no real intent behind it most of the time, we occasionally use it for real useful things like to find out if a new antenna is better or worse than an existing one by comparing it's WSPR spots and distances.

I find that kind of test-and-research aspect of WSPR to be a really interesting and exciting part of our hobby.

Because of that I was really intrigued when I got an order for a WSPR Desktop transmitter from someone working in a place were they do actual research.


I was contacted by Lars Lehnert - call sign SA2LLL in the spring when he inquired about purchasing a Desktop unit to be used on board he Swedish Ice breaker and research vessel “Oden”.

He ended up inviting me to come aboard and checkout his work place.

During the tour of Oden I learned a lot of what is going on there and got a few photos and impressions with me back home so I thought I share it with you my reader as I suspect you might find this interesting as well.


Oden is a Ice breaker that was built in the 80ies with polar research operation in mind at the time it was designed and because of that it is uniquely designed to handle these dual roles.

Technology on board.

Lars handles most of the technical stuff on Oden from radios to computers and research equipment. The technical equipment keeps him very busy while they are out on an expedition but he still finds time to work a bit of Amateur radio every now and then with his HF radio.

He also had some existing WSPR equipment that he wanted to replace with with my WSPR Desktop transmitter.

He intended to run the WSPR transmitter more or less continuously and do band hopping between the four bands 40m,30m,20 and 17m.

One of the first thing that struck me when I got on board was the amount of radio technology they were using.

It is truly amazing and as you can see in my photos below the amount of antennas is mind boggling!

I have to confess my mind started to race thinking of all of the equipment that could be interfered with if the output of my transmitter was not clean enough.

The WSPR TX Desktop and it's design focus of clean output.

It is in environments like this that the heavy output filtering of the Desktop WSPR transmitter really is useful.

The Desktop transmitter besides having at least 50dB of overtone suppression (in some cases/bands the suppression can exceed 60db) also employ an extra VHF low pass filter that suppress the far away overtones in the VHF and UHF range.

This extra filter is needed because of a common imperfection in standard low pass filters that is used to filter output amplifiers.

This imperfection makes the overtone suppression to start to roll off in their effectiveness when we get far away from the design frequency.

I noticed this effect when measuring the filters in early prototypes.

I then decided that the Desktop model witch is the “flagship” model needs to have an extra set of filters to kill of these frequencies effectively even-though the regulatory standards don't require it.

I often curse myself for that decisions when I have to wind the toridal cores for this filter as it is an extra step that takes time in the build process.

But boy was I happy to have made that decision when I was onboard Oden and saw the radio environment it would operate in!

Integration of the WSPR transmitter to an antenna tuner.

Lars had mounted the ZachTek WSPR Desktop transmitter in a rack cabinet that sits in a shipping container on the starboard deck.

The antenna is a end feed wire that is strung up as diagonally up to a railing on the upper deck some 20 meter away.

He had an existing antenna tuner that was used to tune the antenna but one complication was that it was not an auto tuner, e.g it did not automatically tune as needed, you needed to press a button on the front panel to make it tune anew frequency.

To solve this problem I ended up building a small integration board that we put inside the tuner together on a second visit. Here is a photo of it while the tuner is opened up and we do a test run before putting stuff inside the box.

In the end everything worked perfectly and Oden is now on the way to Greenland while creating lots of WSPR spots worldwide from the 0.3W transmitter that transmits on four bands.

Here is a screen shot of 24 hours of 20m WSPR spots while Oden was under way.

The red line is added by me to show the path it has taken from Sweden out on the Atlantic.

The advantage of using GPS for the WSPR position report in all ZachTek WSPR transmitters.

The fact that my WSPR transmitters updates the position from GPS before every transmission is a great benefit in this application as we can use the WSPR transmissions as a position tracker to follow the ship as it makes it way.

The four letter Maidenhead limitation in a standard WSPR transmission can be seen as the grid squares are pretty big but regardless of that one can easily see the route it is following.

Here are some pictures and more information on the equipment on board.

Seen from the port side in Helsingborg harbor. (short Video, click to start it)

Lets starts with a few pictures from the bridge.

The Bridge.

I was expecting more dials and levers but I guess that is an old view of how a ship is controlled.

It is computers nowadays that handles that like most of the stuff in our society. Although they still “talk” to the old industrial control system that is doing the actual control at the lower level. So no big problem if a computer would hang or act up.

There is still a lot of serial communication at the heart of many of the systems Lars told me. RS232, RS485 and so on.

They run Ethernet in many different networks trough out the ship and to interface with the industrial control system that is serial based they transport much serial traffic over Ethernet and then convert to serial whenever needed

Sonar station on the bridge.

The sonar equipment is really advanced and can produce many types of data of the sea and seabed below it. One result of their sonar operations is underwater maps.

There was a picture hanging next to the sonar operators station that I thought I had to include.

I was told that their equipment would produce other types of images but not exactly this kind.

Flight station on the bridge.

The next photo is taken where the person responsible for flight operations has his station.

He operates VHF Flight radios and outside his window is the Heli-pad were they operate a couple of helicopters. This person is also a meteorologist.

View from the flight operations window towards the aft, showing part of teh Helipad. The helipad would have two helicopters on the upcoming expedition so not much room for errors when landing and taking off I would imagine or you would hit the parked one.

Outside, antennas, antennas, antennas

Moving out on the deck we are meet with antennas galore!

They had a bewildering array of antennas that I had a lot of fun going over with Lars, so much cool technology!