2. Van der HEEM and Erres

The radios sold under the ERRES and Aetherkruiser brands were designed and built in the VAN DER HEEM laboratory and factory. On the left you see the founder of the Van der Heem factory, Piet van der Heem. The photo on the right shows the factory in The Hague around 1955, seen from the location where now lies the Utrechtse Baan.

The Development Laboratory

The laboratory was a room with about six engineers, each working at a large (2.5 meter long) oak table; each table had special sockets connected to isolation transformers and voltage stabilizers. The lab used a lot of General Radio test equipment, like VTVMs, signal generators, distortion meters, and the like. The picture shown here was taken at the occasion of the presentation of a new model (the KY529, coming out in 1952); it has the six engineers in the back, and the radio with a signal generator in the front.

Radio development

Technically spoken, the Van der Heem radios show the influence of the predominant Philips style; physiological tone controls are often found, for example. A typical Van der Heem gem is the use of surprisingly large control wheels on the tuning capacitor, the picture on the right shows that of the Erres KY505 (of 1950).

Each engineer had his own specialization: RF technology, Mixing, Power supply, etcetera, but each engineer was responsible for the design of one radio and was supposed to use the knowledge of the others, adapting circuits to the special needs of the radio under design. Not only the circuits were designed in the lab, but also some of the parts, like RF coils and transformers. To ensure that the quality of the receiver would match the competition's, Van der Heem bought a lot of new Philips models and made critical measurements of selectivity and distortion.

During the design a test version was produced, where necessary with the aid of a specialized workshop, for measurements and testing. When the design was ready it was given to the calculation department to see if the production cost would be acceptable. All too often the engineers had to squeeze out another resistor or capacitor to reduce the production cost below the level of the competition (Philips mainly). The KY513, for example, was first designed with a tone control that was later omitted from the design for reasons of cost. When the head of the department, Mr. Van Waasdijk (right), approved the design, production drawings and a production prototype were made in the work shop; the prototype was the reference for all measurements in production radios.

The Tiny KY513

The engineer responsible for the KY513 was Alexander van Gurp, whose assignment was just to produce a radio that was as cheap as possible, leaving no budget for a power transformer. By 1950, all electricity nets in the Netherlands were AC-based, and AC/DC designs were only employed for cost reasons. A four tube design (like the Tesla 306) was considered but gave a lot of stability problems. The low budget also explains for the bakelite cabinet; now very much demanded among radio collectors, but in those days simply the cheapest way to wrap your chassis. Alex van Gurp realised the dangers connected to AC/DC sets very well and made sure that the metal axes of controls were short, and the knobs themselves were long; even if the knobs are gone, it is not easy to touch the chassis. The radio depicted here has later returned to its maker, to be long carished as a family piece (son and grandson of Van Gurp on the left). One to be proud of, because the design quality of the radio is exceptional.

Other designs

There are several Erres radios in my Radio Corner. A more luxereous one is the Erres KY536 depicted on the right, in 1953 among the first generation of radios that could receive the FM band. Dating Erres radios is usually easy, because (since 1941) the first two digits of the type number equal the year. A 1 is added if the radio is adapted for use in the tropics; the KY504 had Long, Medium, and Short waves, while the KY5041 had Medium, Tropical, and Short waves.

In the nineteen thirties, the logo of Erres radios was the "Erres Piet", an orange parakeet. The copy shown on the left is a scan of the last wood type, made in 1938. Erres radios were quite fashionable and were used in the higher circles, as for example shown on the advertisement poster on the right (circa 1935). Actually, the first tube radio I ever possessed as a boy was an Erres, the KY505 of 1950, which I repurchased in 2000.

More Van der Heem Designs

Aetherkruiser AK1500 Van der Heem produced not only Erres radios, but also other brands, including Aetherkruiser; its AK1500 model of 1950 is shown on the left. Aetherkruisers and Erres' were often the same: the Aetherkruiser AK1500, for example, equals the Erres KY504. For Aetherkruisers, the middle two digits of the type number give the year.

In the sixties, Van der Heem took on the design of a line of portable radios for the South American market. Van Waasdijk did some of the measurements on the prototype (photo right), but he found out that the lab measurements in The Hague were not adequate to predict the radio performance in the intended area of usage. So, the measurements were repeated on the beach in Mexico (photo left). Van Waasdijk was born in 1905 and died in 1987 of an accident; his son provided me with some background information and pictures for this article. Some more pictures are found at Hans Hilberink's Van der Heem page.


Gerard Tel, gerard@cs.uu.nl.