Erres KY-597 (1958)

The Model

The Erres KY-597 is a tabletop radio from 1958 manufactured by Erres, Van der Heen NV in The Hague. It was the flagship model of their line introducing "semi stereo" tone control (there were no stereo radio broadcasts by then). The "Super 7-F", as it was marketed, had a flat, low-profile body that would become the dominant trend in the 1960s. The body is walnut wood with a plastic front panel with details in brass.

It uses 6 vacuum tubes to deliver the usual short, medium and long AM frequencies, plus FM (up to 100 MHz).

It is a gorgeous living room radio, with great sound, and a style that still catches the eye more than 60 years later.

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The Object

I purchased this radio around September 2020 for 37,50 euros at the thrift store Het Goed in Best, The Netherlands. This store is a 10 min drive from my house and I often go treasure hunting there. That day I had a great catch, but there was quite some work involved in bringing this beast back to life.

The radio wasn't in a great state. The wooden cabinet was stained (people couldn't resist using these big radios as cupholders or plant hangers) and the left side of the cabinet was torn apart from the rest. Looking at the overall state, I wasn't brave enough to try to plug it in, even with a current limiter. I plunged straight ahead into restoration.

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The Restoration

Taking the chassis out of the cabinet is a major hassle on this radio. Behind the front plastic panel there is a plywood panel fit in an awkward way. The fact that the side panel of the radio was already off ended up being a good thing.

The service manual of this radio is fantastic, with a thorough list of components including all capacitors and their types. It turns out that theses radio had tens of paper and electrolytic capacitors that clearly had to go. But in order to get to all nooks and crannies to unsolder the old caps, I had to build a wooden frame to be able to move the radio in all positions. It was inspired by this video on the great YouTube channel "Electronics Old and New" by M Caldeira.

Now that I had easy access to any part of the radio, the recapping games begun. The pictures below are just an example, there were tens of caps to replace.

Old Caps

New caps

Inspecting the tubes, I noticed that the ECC85 used for the FM frontend was gassy. It is easy to spot because the top of the tube becomes white. I ordered a replacement tube via Marktplaats (the Dutch equivalent of eBay) for about 15 euros.

(I don't have a good picture of the gassy tube, but I found this image on the web of another tube with the same issue. Air has entered into the tube and killed it).

At this point, I've done a very, very stupid thing. While cleaning the speaker cone with a brush, I applied too much pressure and broke the paper. I fixed it with bison fabric glue and coffee filter strips. The result didn't look that great, but it is hidden under the cabinet, and it saved the speaker.

A few weeks later, while working on the radio, I made an awkward movement and damaged the other speaker as well! That taught me a lesson: always cover the speaker with a carboard sheet. After a couple of hours of guilt and self-chastisement, I fixed the other speaker with the same technique.

A gassy tube (not the same from the radio)

At this point, the radio was working again. The video below has poor audio because there was no proper antenna, but the fact that I had reception at all indicates how good this radio is.

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At this point I noticed that the volume was scratchy and trebles were poor in all tone presets. It turned out to be a dirty potmeter. I had to open it in order to clean it, and it was very difficult to remove and disassemble. But in the end it was worth it, the scratchiness disappeared and the tone became sharp and brilliant.

Cabinet Restoration

The wood was in such a bad shape with water stains and discoloration that I decided to strip the original varnish and refinish the cabinet. This is how it looked before restoration.

I started out by stripping the varnish using a stripper gel and a scraping tool. Then I applied white spirits with a cotton cloth and gave it a good rub.

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It looked great. The water stains had damaged only the old varnish, but not the wood underneath. The next step was fill some dents using wood filler and apply a nice coat of wood stain. I made a poor choice of wood filler, which had a lighter color than the wood. I wish I could go back in time. Oh well.

I proceeded then to buff up the brass trimmings with a steel sponge and some polishing paste.

As usual, I have cleaned all plastic parts with a toothbrush in a warm soapy bath. The plastic front panel had a grill cloth glued to its back that was dirty, rotting, and torn in some places. My wife found a similar fabric, and dyed it with tea (!) in order to get the right color. The same treatment was applied to the side grills.

Now for the last step I had a difficult choice. I had to reseal the wood finishing with new coats of varnish, which is something you normally do after gluing all wood together but before putting the chassis back in the radio. However, I knew I could never get the chassis back in place after gluing the side panel. I decided to put the chassis in, glue the side panel, mask all the non-wood parts of the radio, and the apply the coats of varnish.

Result

When everything was finished, I was ecstatic at the result. This radio looks awesome and has a great sound. It's been since then one of the centerpieces of our living room. We love it, cherish it, and use it almost every day.

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