[Dept. of Computer Science]

Erres KY513 Mini Radio

Our Department and University.
See my other radios too! (Here is the next one.)

A nice and small bakelite radio donated to me in the early stages of my collector's carreer. It has ever been one of the highlights of my collection and regularly served in the family's living room.
Data for this radio
Type Erres KY513 Mini Radio
Bands LW (975-2000 m), MW (175-580 m), SW (15-53 m).
Cabinet Dark bakelite; 32x20x13 cm.
Tubes UCH42 (osc./mixer), UF41 (IF Stage),
UBC41 (det./LF prestage), UL41 (output stage),
UY41 (rectifier), 2 dial lights.
Controls Volume/off, tuning, band switch.
Power AC/DC (125/220 V) 40W.
Produced The Netherlands, 1951.
Selling price at introduction: 207.50 guilders.
Condition: cosmetically excellent, working very good.

The Van Der HEEM Development Laboratory

The radios sold under the ERRES brand were designed and built in the VAN DER HEEM laboratory and factory. 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.

Radio development

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). When the head of the department, Mr. Van Waasdijk, 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 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. 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.

Gerard Tel, gerard@cs.uu.nl.