RADFORD
Test Equipment
The first dedicated audio test
equipment I used professionally was the Radford Low Distortion
Oscillator (LDO) and the matching Distortion Measuring System (DMS) in
the early 1960s. This was the first generation
equipment with valve circuitry and although measurements were slow
& tedious because of the need to use multiple controls to
balance the bridge, it was capable of measuring distortion down to very
low levels. Certainly to below 0.01% which at the time was a real
achievement. This equipment was developed by Arthur Radford, the
founder of Radford Audio, who needed good quality test equipment to
test his amplifier designs. As I recall Arthur started out making very
good transformers and became skilled at designing and winding the
output transformers for valve amplifiers so somehow he drifted into the
audio industry. He was a designer who always sought better
and this became his biggest failing; he could never leave a design
alone. He would engineer an improvement then tell the production line
to stop so that the latest improvement could be added. Great for the
customer but not necessarily so good for the financial health of his
company.
This
test system
was developed into a Series 2 version which used transistor circuitry
and finally into a Series 3 version. However it was still a manually
operated system and could not compete with the likes of Sound
Technology and so Radford instruments faded from the field.
Below is a picture of the original valve powered Low Distortion Oscillator; what you might term as the Series 1. The valves can be seen in the interior shot.
Below is a tired looking example of the Series 2 Oscillator also showing the internal valve circuitry.
The Series 3 product looks a lot more modern and used transistor circuitry throughout
The picture below shows the matching Series 3 Distortion Measuring System
The pictures below are some interior shots of the Series 3 LDO
Downloads <click on the logo to download> Thanks to Jim Anderson for some of the manuals |
The manual for
the Low Distortion Oscillator Series 2
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The manual for
the Distortion Measuring System Series 2
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The manual for
the Low Distortion Oscillator Series 3
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The manual for
the Distortion Measuring System Series 3
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Owner's Manual for the SC24 Control Unit
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Radford Distortion Measuring Set Series 3 Leaflet No.A52
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Radford Distortion Measuring Set Series 3 Technicial Manual BC51
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Radford LDO3 Leaflet A51 Jan 75
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Radford LDO3 Technicial Manual & circuits BC51 + M3366-2 Control
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Radford Hi Sesitivity Volt & Noise meter - Leaflet A53
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Radford Hi Sensitivity Volt & Noise Meter Technical Manual
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