Erres KY485 radio (1948)

Erres was a more or less independant radio maker that made good and affordable radios. The KY485 was a lower mid range model. It has an economic valve line-up, using three valves with a double system plus a rectifier. These are ECH21 as frequency changer, ECH 21 as IF amplifier and AF pre-amplifier, EBL21 as detector and output amplifier and an AZ1 rectifier. The '20 series valves have a Loctal base. These were innovative in the early fourties but were replaced by the smaller noval (9-pin) and miniature (7-pin) in the fifties. The Loctal tubes and the square dial are the reasons why I wanted to have this radio.

I bought it in May 2003 through an advertisement site. The seller said it hummed terribly so he could not tell whether it was receiving anything.

The cause of the hum became obvious immediately when I removed the back panel. The power supply electrolytic had leaked and dried out. I replaced the electrolytic, the coupling capacitor to the output valve and the electrolytic for the negative bias voltage. And I had to repair the antenna input, using some epoxy cement.

After switching it on, I got a terrible hum. What was wrong? I had fitted a different electrolytic that had a slightly larger screw thread so its case did not make contact with the connection lug. After fixing this, I got complete silence.

There was not even a tiny hum as I touched the gramophone input. This was cured as I replaced the second ECH21. But still no reception. I replaced the other ECH21 and now the radio played. I saw that both ECH21's had cracks around some of their pins. A loss of vacuum may have been the cause, although the getter inside the valves looked good.

After this, the radio played fine and I was really satisfied by its performance. But in 2008, I needed to trade this little old radio to make room for others.