Item nr.

Erres KY504 Table top

Modest working class radio

Data for Erres KY504
ProductionThe Netherlands, 1950.
Price was 198 guilders.
BandsLW (950-2000m), MW (175-580m), SW (15-55m), IF 452kHz.
TubesRimlock ECH42 (mixer), EF41 (IF amp), EBC41 (detction, AVC, AF amp), EL41 (output), AZ41 (rectifier), 2x dial light.
PowerAC, 6 voltages, 40W.
DocumentsService docs.

The Design

The Erres KY504 is sometimes referred to as the cheaper companion to the KY505 of the same year. The radio is indeed cheaper at a price of 198 guilders, where the KY505 was 240. But the models were electrically almost the same, and the differences were small. The look of the KY505 is generally highly appreciated, while the KY504 is considered a plain functional wood box. What I like more about the KY505 is that is has all controls in front, where the KY504 has the tone pot and band switch at the side faces. But the 505 has curved wood panels, highly appreciated but expensive to make. Both models had different subversions, by the way: I have seen pictures of the KY504 with dark brown knobs and wood strips.

With Medium Wave tuning up to 175m, or 1710kHz, the radio covers the American part of the Broadcast band, 1600 to 1700 kiloHertz. Europe used only frequencies up to 1611kHz. The close-up of the dial shows the band coverage (up to 175m), but also some stations considered important by Erres with their assigned channel number in the Copenhague band plan. Erres calls this a "floating dial" because it is only connected at the lower edge, the sides and top edge run completely free.

Here is a detail of the back panel, showing the tube layout and how to connect aerial and ground. The radio does not have the, quite common but rarely used, extra loudspeaker connection.

Obtained10/2018 from Leo (Utrecht); sn=7971.
Condition8; works very well with new capacitors and wiring, dial and knobs very good, woodwork has some damaged spots.
Sound samplePLAY SOUND   With the Broadcast Band (Medium Wave) going as high as 1700kHz, the Erres is able to receive MW pirates. The stations, often from the east of my country, come in quite vaguely.

This Object

I replaced the tone correction, B- smoothing, coupling, and HF screen capacitors before switching the radio on. It then turned out that the wire feeding g2 of the output tube (and several other tubes) was not properly connected to B+. I rewired all connections to B+ (located around the smoothing capacitor, which was clearly replaced). In this process, I probably interchanged the soldering connections for the first and second filter cap. Still the radio didn't work, and then I found out that the center tap of the B+ section of the transformer wasn't grounded. That is because I corrected a short of the filter cap can to ground. After adding one connection, the radio worked.

It is good practice to start up old radio's with a series light bulb, but bad practice to keep it there while measuring voltages. I found the B-, supposed to be about -6V, to be only -2.8V and sound distorted! Then my eye fell on the series bulb, which reduces not only B+ voltage, but also heater temperature. Witha 40W in series, B- is 2.8V, with 75W it is -5.0 and without bulb it is -7.3V! The radio really works a lot better then! The chassis view shows the large drive wheel for the tuning capacitor, typical for Erres sets. It also shows the attached coil box at the capacitor end; it is almost as if by accident the chassis was produced too small and some extra box was added.

The power chord was quite a mess, with a screw connection and a switch, while the switching pot was still functional, so I removed all unnecessary stuff there. The tuning drive chord was wound the wrong way around the knob axis: dial and condensator would be properly directed, but you had to turn left to move the pointer right. I rewound the chord according to the service doc, here keep in mind that, seen from the knob, the wire running UP to the condensator is BEHIND the wire running DOWN to the right guidance wheel.

Part of Gerard's Radio Corner.
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