Elektorscope

Anybody who loves scope kits, should understand how unique this DIY scope is. It has been built after the Elektorscope design. In 1975 Elektuur ran a series of articles on this DIY scope. The design had a modular set-up: one had the option to build one or two Y amplifiers, there were a number of improvements for the time base and the amplifiers, and the design could be modified to accomodate different types of CRTs, so if you had a decent CRT at hand, you could build your scope around it. Elektuur sold PCBs and front plates for this design. The front plates were modular: a front plate for every module so if you'd want to build a four-channel scope, you'd have four four amplifier fronts. They had two types of front plates for the CRT: a mall one for 7 CRTs and a larger one for 10-15 cm tubes.

I read the series of articles a few years after publication and was excited about the idea to build a desirable instrument such as a scope myself. But I didn't have the time nor the money so to build an Elektorscope remained a dream.

Recently, I saw an Elektorscope on an Internet auction site. The person selling it hadn't built it himself but the device had been given to him by the original owner. He showed me the CRT had a trace with showing some kind of distorted square wave. Maybe the signal of the two-channel adapter (what else could the signal be?). He couldn't measure anything with it. We reached an agreement and I took home quite a heavy scope.

My Electorscope has a largish (12 ) crt and looked like the original builder has done his best to make a good looking instrument. Though I don't share his taste for grey paint with sand sprayed all over. This might have been an attempt to imitate wrinkle finish as used on old professional measuring equipment.

At home, I removed the lid of the case to take a look inside. The case is constructed from aluminium U and L profiles and flat sheet aluminium, sawn to size and bolted together. A good way to construct an equipment case to size, if you don't have the means to ply aluminium sheet.

The large CRT is mounted within a magnetic shield. I cannot see what type it is.

And because of the, ehm, resourceful construction used to mount the CRT, it is not really easy to get access to it. The constructor doesn't seem to have tried to saw the shield to size. This is fortunate because the specific type of alloy used for these shields is hard to work and looses its high mu when mistreated. In the back, there are two power transformers. One has a number of low voltages, presumably for the pre-amplifiers. The other is mounted beneath the first one, this seems to be an HV type, needed for the CRT supply and output amplifiers. There is a HV power supply PCB with some odd capacitors mounted to the frame. These are presumably part of a voltage doubler.

I will collect my old Elektuur magazines and see what needs to be done to fix this nice old scope.