SPARC Radio Museum - Eddystone S.680X Restoration

Restoration of an Eddystone S.680X
Gerry O'Hara VE7GUH
Apr 2007

Restored Eddystone S.680X.

Gerry has a penchant for British Eddystone receivers - he had been looking out for a Model 680X to add to his collection for some time, and although one or two had appeared from time to time on EBay, he saw nothing locally. Then he had a brainwave, SPARC had one on display and he thought 'why not restore the museum's S680X?': he would get to know the receiver, could use it for a while, be able to write an article on it and give it back to SPARC refurbished and working ...a 'win-win' for all.

So, he signed out the museum's S.680X (S/N GJ1318, manufactured in July, 1958), and set about restoring it to pristine condition. The Eddystone 680X had a ten year production life, from 1951 to 1961, during which time some 1,562 sets were produced. The S.680X covers 480KHz to 30MHz in 5 bands and is a single-conversion superhet with two stages of RF amplification. These are professional grade receivers and many were supplied to the armed forces.

A look above and under the chassis indicated that the set was physically in good shape - all parts appeared to be present and correct and there was no evidence of anything being replaced, overheated/burned out, or any physical shorts or damaged wiring. Continuity checks on the power transformer indicated that it was in good shape, the fuses were ok and the mains switch worked.

Front panel before restoration.

The power supply and IF/AF sub-chassis in this set are finished in a grey enamel paint, as are all the IF transformers, crystal filter unit, BFO unit, tuning gang cover, power supply choke and AF output transformer shrouds, making for a very uniform and professional-looking chassis. The RF section is built on the usual stout Eddystone aluminium alloy casting, the outer surface of which is also painted grey. The chassis was covered in a light coating of fine dust, some fluff and a few dead bugs, but otherwise was in remarkably good shape. The coil box cover was removed to allow access to the tuning gang and I then used a paintbrush and vacuum cleaner to remove the loose dust and debris (above and below the chassis) and then wiped the chassis over with a cloth moistened in warm soapy water - it came up a treat with very little effort. The grey crackle-finish case was also cleaned with warm soapy water, this time using a soft nailbrush: it cleaned up like new apart from a few minor scuff marks. Time for initial power-on - all went well, and following several tweaks and minor repairs, the set was re-aligned and set to work on the shortwave bands.

Although the tuning mechanism was running quite smoothly, the dial glass, pointer and scale plate cannot be cleaned properly without dismantling the front of the S.680X, meaning separating the front panel casting from the main chassis had to be undertaken. That was the next job... a bit of a task, but well worth the effort.

In use, Gerry found the set to be extremely sensitive and very selective on all bands, right up to 30MHz - indeed he thought it one of the best valve receivers from this era that he had ever tried out: very stable and a pleasure to use. Of course, Gerry was reticent to hand it back to the Museum. The Eddystone S.680X is an excellent receiver and this one is now (almost) like new. The SPARC museum has a first-class Eddystone exhibit that the folks at the Bath Tub (nickname for the Eddystone factory) would be proud to know is on display... and, of course, Gerry is still on the look out for one of his own.

A more detailed description of the restoration is available in PDF form.