Eddystone Edometer 902, Wavemeter S696/1 & Modulation Meter S33

Eddystone Test Gear

Eddystone made a number of small items of test gear for the amateur radio community which are quite hard to find these days. This page describes some units that I have owned as there is little on the net about them apart from some summary information on the Eddystone User Group web site. Those appearing at auction seem to be snapped up quickly. I would be interested in copies of the instruction leaflets for the S33 and S696, though neither really requires them.

Edometer Model 902

These units are seldom seen and there is little on the internet about them. My Edometer dip oscillator was made in December 1969 according to the serial number LU0950. It is a nice transistor based unit with the trademark Eddystone dial. It operates from a 9V battery and covers from 370Kcs to115Mcs in 7 ranges with the usual plug in coils. They were supplied in a nice wooden case complete with manual.

It makes a handy source of low power RF for testing vintage equipment, though obviously accuracy is not high. They are quite collectable with Eddystone enthusiasts, but rarely come onto the market. Mine was purchased some years ago at a swapmeet.

A copy of the specification leaflet and manual is available from the BAMA website.

Absorption Wavemeter Model S696/1

This unit is a good deal older than the GDO as its serial number FD0293 dates it to June 1952. It is extremely simple consisting of a meter, a tuning capacitor and diode. It comes in a painted steel case, with plug-in coils, but a few of these are missing or damaged. The unit is in working order, although the meter is a bit sticky at high deflections, probably through lack of use. It had been stored under poor conditions so that the meter and case needed repainting.

The unit is the opposite of a GDO in that it measures RF radiation and requires no power supply.

I have found little mention of these units on the net and have no instruction leaflet and have never seen another one. They are rare and again would be of interest mainly to the Eddystone collector.

Modulation Meter Model S33

This unit is in virtually mint condition and complete apart from the aerial and a leaflet. The unit measures the modulation percentage of an AM transmission. A set of 6 coils is supplied with it covering the HF amateur bands of its time (1948-1956). The unit requires no power source and has two germanium diodes. The meter is first set up by turning the rear switch to SET and aligning the needle to the red set position by changing location or adjusting the aerial. Once this is done, the switch is turned to % MOD and the % modulation read off.

This unit has the original box marked as Cat No 678 and may have been sold under this type. The meter is marked AA886 singnfying that it was made in Jan 1949. The antenna fits but I believe the original was a telescopic unit to allow fine tuning to set the meter.

The unit is of little practical use today, but is an attractive item for the Eddystone collector.

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Count since 28/6/07.
Page maintained by Simon Buxton VK2UA . Created: 8/01/06 Updated: 8/04/2008