1956 Siemens resistance decade box

 

Frontpanel

Frontpanel

This ex Holland Signal precision resistance box had broken 10k resistors.  This was caused by corrosion of the copperwire that connected to the top of the resistor. The strange thing was that it only happened to the top wires.

It is a precision decade.  The zero ohm resistance is very low. They use two types of metal for the conductors from resistors to output.

The label

The label

The zero resistance 0,0138 ohm.

Two different conductors

Two different conductors

Under the front panel you find the big scaled knobs.

The knobs

The knobs

Under those disks we find part of the magic. Heavy duty low EMF, low resistance switches.

the switches

the switches

If we look at the next picture you see the switch is made of several parts. All bolted to the metal plate.

Switch details

Switch details with fresh petrogelly

no words needed

no words needed

You do not want to know the price of this resistors. The 0.1 ohm is nothing more as a loop of manganin wire.

+10kg wire wound ceramics

+10kg wire wound ceramics

They are beautiful made from manganin wire wound on ceramic pipes. Look at the ropes that fixate the ends.

Repairing a 10k resistor

Repairing a 10k resistor

Some of the 10k resistors are now just outside the specs but as l;ong as you knowe it does not matter.

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