The Armstrong 500 Range and Ted Rule

The electronics of the 500 series tuners were similar to those used for the 400 range, although the external appearance was very different.

The above picture was taken in 1969 or 1970. It shows Ted (E. A.) Rule testing a 523 FM tuner. Ted is perhaps the best known designer who worked for Armstrong. He joined them in about 1950 as a tester. At that time George Tillet was their audio/radio development engineer. However George decided to leave about a year after Ted joined, and Ted was then invited to take over as the development engineer for amplifiers and tuners. Ted filled this job very successfully for around 25 years, and only left the company in 1976. As a result, he was responsible for almost all the designs described in these pages. The length of his service, and Armstrong's steadily growing success during this period is a testament to his ability.

The above shows a closer view of the tuner being tested. Beside it to the right is a rack of boards. These are probably M8 Stereo Decoders. These were optional, plug-in, decoders for the 500 tuners and receivers. From the presence of these boards, and the shapes of the waveforms shown on the oscilloscope screen in the first photo, it seems probable that Ted was checking some M8 boards when the photo was taken.

500 Range Tuner Specifications

FM coverage	88 - 109 MHz	Sensitivity	1·5 microV (mono) 5 microV (stereo)
IF	10·7MHz centre	220kHz bw (-6dB)	80dB rejection
Frequency Response	30 Hz - 15 kHz ±1dB	Separation	30dB
Hum and Noise	-60dB	Filters	38kHz, -40dB
AM section	4kHz bw	5 microV sensitivity	mw/lw

Ted was and is a radio amateur who learned a great deal about electronics (RF in particular) whilst serving in the RAF. As a result of this, his tuners were usually something special. This probably reached its peak in the 600 range which used a double IF conversion technique. However the 500 tuners also earned a high reputation. For example, when the BBC fitted out new studios in Hanover Square for BBC London in 1970 they purchased a set of 500 tuners for off-air monitoring. These were used for two purposes. The first was to monitor the signals actually being transmitted by BBC Radio London. The second was for when BBC London itself was not producing programmes. Then the 500 tuners were used to receive BBC Radios 2, 3, and 4 in order that one of them could be rebroadcast. At that time the majority of BBC stations used Armstrong tuners due to their stability, reliability, and performance.

The above shows the rear view of a 526 receiver with its case removed. As with the previous pair of pictures this is a detail from a larger image which can be seen below.

The overall picture gives a clear view of the development lab that was used at Armstrong. This lab was used for many decades, probably from the end of the second world war, right up until development ceased at the end of the 1970's.

Content and pages maintained by: Jim Lesurf
using HTMLEdit and TechWriter on a StrongARM powered RISCOS machine.