Gerard's Philips PR9500

190
Item nr.

Philips PR9500 Conductance meter

Conductance meter

**Data for Philips PR9500**
Production	The Netherlands, 1957. Price was 450 guilders.
Tubes	EF40, EM4, EL42, EZ40.
Cabinet	Steel. Size 25x17x12 cm.
Power	AC (110-240V) 15W.
Documents	User manual, email from Wim van Oirschot.

The Design

The electrical conductance of fluids is about proportional to the concentration of solved materials. This machine was used in industrial laboratories to verify water quality; this was important in for example drinking water production, but also for the inflow of cooling water in electricity plants. A typical user would first produce reference tables by measuring the conductance of water with known concentrations of solvents (at a specific temperature, like 20 Celcius typically). Then test samples could be determined quickly by a simple electrical measurement.

Obtained	12/2001 from Hans Agema.
Condition	8.
Disposed	Sold 5/2012.

This Object

I got it in exchange of an Eddystone radio. Wim van Oirschot provided me with some background information on the model. As the meter is basically a quite accurate measuring bridge for resistors, it became a popular hobbyist tool for measurements of resistance. You can also measure capacitors and coils quite accurately by supplying reference capacitors or coils on the external reference point of the bridge. With my daughter I did some chemical tests and we were able to reproduce unknown concentrations quite nicely after making reference measurements.

Part of Gerard's Radio Corner.
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