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Robertson R-Super 2S

This is how it looks now after I restored it

First a historical flashback:

Thorleif Robertson-Olsen
(1909-1983) was born in the Norwegian port town Egersund. When he was 14 years old, he looked in the magazine
Allers Familiejournal and read a detailed description of a radio receiver with three tubes. He asked his father, who was the horologist of Egersund, to give the permission to buy such a radio for 700 Kronor. That was an enormous amount of money back in 1923, and of course, the father said no. Then Thorleif went to his teacher who lended him the money needed, and Thorleif constructed his first radio. Thorleif was very talented and made experiments with the radio and modified and improved it. After some time Thorleif constructed more radio receivers and eventually began to design them as well.
In 1931 he started a radio warehouse business, and he also started classes where he taught radio electronics.

During the war, when the Germans occupied Norway, Egersund was one of the first towns that they occupied, because of its excellent harbor and the telegraph line to England.

Thorleif was taken by the Gestapo and was put in the prison
Polizeihäftlingslager Grini outside of Oslo. During the imprisonment he managed to sneak some radio literature in to the prison, so he was able to keep on teaching his fellow prisoners some radio electronics. In that way he made the foundation for a future radio production. He employed several of his fellow prisoners when he founded the company Robertson Radio-Elektro A/S in 1946.

Svanedal Ullvarefabrikk
The wool-factory Svanedal Ullvarefabrikk *

The activity was placed in the attic of the wool-factory Svanedal Ullvarefabrikk. In 1946 Thorleif bought about 3000 units of transmitters, of mainly two types, on the American surplus market. Thorleif and the approximately ten employees converted and modified the units to fulfill the demands of Telegrafstyret (the Norwegian Telegraph Service) to be installed in Norwegian fishing vessels. They came on the market as the Radio-Telephones 4601/461 and 4770/475. Robertson was the first to launch this kind of products on the market.

Svanedal Ullvarefabrikk
The attic of the Svanedal Ullvarefabrikk in 1947 *

At the same time as the surplus transmitter modifications toke place, they also began designing their own transmitters and receivers. In 1948 the first products of Robertson origin was launched. It was the 4840 and 4915 transmitters.
The receiver R-Super came on the market in the fall of 1952. It was equipped with the EF39, ECH35, EBC31, EL33 and EM4 tubes. Approximately 550 units was made, until December 1955.
The R-Super was developed and became the R-Super 2. It was launched in the fall of 1955. The R-Super 2 was made in several special versions to other countries like Sweden, Belgium, France, Portugal and Peru.
Initially the anode voltage was generated by a vibrator power supply. Then a rotating converter. The first transistorized converters was of the Vingtor brand, but was soon replaced by Robertson designs. The last version of converters used the 2N3055 transistors and was extremly reliable. Normally the R-Super 2 was meant for 12VDC or 24VDC but versions for 110VDC and 220VAC was also made.
Special versions with squelsh control and other refinements was also made. There was totally 2458 units made. The last batch was delivered to France in October 1969.
Further development of the R-Super series was made. For example, the R-Super 5 and R-Super 6 that was produced until the early 1970's when transition to SSB began.

In 1948 Robertson started the developing of an Auto-Pilot for vessels. In 1952 it was launched as the AP-1.

In 1951 Robertson launched a tape-recorder for use in corporation offices. It was called the Tape-Riter. Again, Robertson was the first to launch this kind of product on the market. Vebjørn Tandberg realized its potential and decided to produce a tape-recorder for music.

Robertson Radio-Elektro A/S
Nyåskai on the Eigerøy island *

In 1952 Robertson bought a site at the Nyåskai-area on the island of Eigerøy, of uptown Egersund. A new factory was constructed and Robertson left the wool-factory attic. Today, the company is still at the same Nyåskai-site.


At that time the product portfolio held transmitters, receivers, radio-telephones, radio-compasses and auto-pilots.

In 1971, the same year as the Robertson Radio-Elektro A/S had its 25 year anniversary, Thorleif Robertson sold the company to Kongsberg Våpenfabrikk A/S  (the Kongsberg Weapon-factory).

In 1984 Kongsberg sold it to Bird Technology in Bergen and the name was changed to Robertson Tritech A/S.


Another Norweigian company, Simonsen Radio A/S in Oslo, was founded in 1947 by Willy Simonsen (1913-2003) being specialized on echo-sounders and radio-telephones for fishing vessels. In 1967 the company established an office in Horten and changed the name to Simrad A/S. In 1993 Simrad A/S acquired the Robertson Radio-Elektro A/S and changed the name to Simrad Robertson A/S.

In 1996 the Kongsberg Group bought the company back again and merged it to the new founded company Kongsberg Maritime A/S.

In 2005 the Kongsberg Group sold most of the Simrad Yachting company to the Swedish investment corporation Altor Equity Partners.

In March 2006 Altor acquired the Lowrance Electronics Inc.

In September 2006 Altor merged the Simrad Yachting and the Lowrance Electronics to the new founded the Navico company.

In 2007 the Navico company acquired the Brunswick New Technologies company (the Marine Electronics division).

What ones was the Robertson Radio-Elektro A/S became the Navico Egersund A/S.

In December 2008, the Haaland Group intended to acquire 80% of the company. In January 2009, the agreement was signed and the manufacturing part of the Navico Egersund is now the Haaland Elektronikk A/S. The Haaland Group is a specialist in thin sheet-metal and have had a business relation to Navico for several years.

Haaland Elektronikk
Haaland Elektronikk A/S on the Eigerøy island 2009  (Photo: Dalane-Tidende)

* Pictures and some facts comes from the book "Fra glødelampe til trykte kretser" by Alf Fagerheim in 1974.

And now my  Robertson R-Super 2S  that is the 2nd version of  Robertson R-Super. The serial number is 011 and it is manufatured in December 1955.

First I say Thank You to Einar Birkeland who is retired after almost 40 years at Robertson Radio-Elektro A/S. For several years, Einar was doing final inspection, testing and maintenance on the R-Super receivers. He was also partly resposible for the development of the last versions of the R-Super receivers. Einar has given me the production facts and other technical information. I also say Thank You to LA9CHA Thorvald Jacobsen at Navico Egersund/Haaland Elektronikk that helped me to get documentation and schematics for the 110VDC version of the receiver. I also say Thank You to The Radio History Society of West Sweden that helped me to get documentation and schematics.

Robertson R-Super 2S  is a radio receiver for vessels, having six frequency ranges:
150 ... 270 kHz
270 ... 500 kHz
600 ... 1600 kHz
1.6 ... 4.2 MHz
0 ... 9.5 MHz
9.0 ... 20.0 MHz

The intermediate frequency (I.F.) is 570kHz and the tubes are: 12AU6, EF41 (3 pcs.), ECH42, EBC41, EL41 and a
"magic eye", EM-71, as a tuning aid. It has a built-in BFO for CW and SSB reception.

R-Super 2S
This is how it looked when I bought it

When I bought the radio, it was modified by a previous owner as described here:
The "magic eye", EM71, was removed and replaced by a moving coil instrument on the dash board, and served as an S-meter. The opening, where the EM71 used to be, was covered with a yellow painted piece of sheet-metal (can be seen in the picture behind the frequency dial).
Two power supplies was constructed in the receiver, one for the filament and one for the anode voltage, since it originally was meant for 12VDC or 24VDC supply. A transistorized converter has originally been installed in the receiver to convert 12VDC or 24VDC to 250V anode voltage, but it was removed.
A power switch was placed on the dash board, to replace the broken one that was originally incorporated with the volume potentiometer.
The output transformer in the audio amplifier was replaced, which caused the EL41 tube to exceed its allowed limiting values.
A loudspeaker was mounted to the right side in the cabinet.
Several wires were cut and the cabinet was repainted in a blue color.
In general, the radio was in a bad condition and the modifications were not well done. The power supplies were even constructed in a way that made them dangerous.

R-Super 2S
Filthy internal and dangerous power supplies

I have removed the moving coil instrument and mounted a "magic eye" in its original place. I did not have any EM71 though, so I used a CV51 (Y65) instead.
I have replaced the volume potentiometer and mounted a matching knob.
I have mounted a new power switch next to the volume potentiometer.
I have increased the value of the cathode resistor for the EL41 tube, to get it back within allowed limiting values.
The openings in the dash, where the moving coil instrument and the power switch used to be, is covered with a new dash decal of my own design with the Robertson-logo of the time.
I have made a new power supply and mounted a connector for the power cord.
I have painted the cabinet in a gray color. The cabinet was originally in a gray style but maybe different from the one that I painted.

ML-46  R-Super 2S  R-Super 2S
The coil system from the bottom view

R-Super 2S
The chassis cleaned and the power supplies removed

I have made a new power supply out of two identical transformers, connected 220V/6V and 6V/220V to make the necessary filament and anode voltages. 230V mains voltage to the primary 220V winding, result in almost exactly 6.3V at the secondary winding for the filament supply. Rectifying and smoothing at the anode winding results in approximately 230V anode voltage.

Trafo  Two identical transformers  220V/6V ...
Trafo  ... mounted together using threaded M6 rods ...
Trafo  ... and mounted to the chassis using the same M6 rods

The smoothing filter capacitors fits perfectly in brackets for 32mm PVC pipes

The new power supply in place

My receiver is apparently made for the Swedish market, since it has Swedish texts on the dash board

Schematics of the original receiver

Schematics of my modified receiver


Schematics of the coil system and the original transistorized converter

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