Eddystone 680x

[Steve G4WCS]

I've been kindly given this by a fellow dog walker who noticed my antenna farm at home.
I intend to bring it back to life, it's been in his attic for 20 odd years but it was working and in good alignment before being stored. It should tidy up nicely. Any tips or pointers gratefully accepted, I have restored a couple of domestic valve radios so am aware of recapping, powering up via a lamp limiter etc. Are matching speakers available ?

[G3PIJpeter]

Have a look at the Gerry O'Hara S-680X restoration article at
https://eddystoneusergroup.org.uk/Re...ne%20S680X.pdf
- Peter

[HamishBoxer]

There are matching black crackle speakers available, mostly on Ebay. Possibly £40 upwards at a guess, cannot remember what mine cost.

Try a Wanted on the forum. They are round BTW.

[turretslug]

Nice lucky find there of a classic comms receiver- comprehensive facilities yet (for the breed) straightforward circuitry. They are close-packed inside, though, the coil-box innards are particularly challenging. Looks to have had a few things done to it (I hesitate to use the perjorative term "got at", some after-the-event changes can be useful and beneficial and even improve safety, assuming they've been done with a bit of care). The original Eddystone mains connector has somewhat "incidental" earthing dependability, and is scarce nowadays anyway, so the fitting of the round Bulgin-type connector is understandable. I'm slightly puzzled by the valve at the rear corner of the chassis behind the mains transformer next to the shunt stabiliser, normally this would be a 5Z4G rectifier or similar, I don't think Eddystone ever updated to something like an EZ81 or whatever it is there. Could always be wrong though. The indexed hole next to those valves was originally for a 1.25" fuseholder, both sides of the mains originally being fused, so I'm guessing it's now live-side only. The smaller knobs aren't original- my 750 had had these replaced by glitzy '70s plastic things more suited to a hobbyist mixing desk kit or such like, i.e. about as inappropriate as they could be! I used those 1" dark Bakelite 12-ridge types used on much military kit and often found at rallies, even NOS, which IMHO suit it rather well.

Judging by the rust on the transformer lam stack and shroud, I'd be inclined to leave it by a radiator or in the proverbial airing cupboard for a week or so before powering to guard against any tracking in it or within IFTs or other awkward happenings.

[G6Tanuki]

Cleaned up, lots of old 70-year-old age-decayed parts [capacitors, resistors] replaced, some wiring on the mains-side re-engineered to be safe, and a sensible realignment job done - and you'll have a really rather good SW receiver with which to tune around and enjoy the remaining operators on HF.

But - if there's maybe an open-circuit IF transformer [green spot syndrome] the cost of properly fixing it could be horrid.

I'd say "Go for it!" Though old free-tuning radios really have problems with modern SSB transmissions, it can be great fun noodling around on the HF bands at 03:00 when you're struck by a bout of insomnia.

[I have an Eddystone 840A as my bedside radio]

[Steve G4WCS]

Thanks all, he did mention something about a couple of upgrades and “changing the diode” when he was keen. Good shout on the knobs, I've probably got enough Eddystone Bakelite knobs in the knob tin. Will leave it inside for a few weeks under the stairs with the boiler before doing anything.

[Steve G4WCS]

Found some more appropriate bulgin knobs in the knobs tin, and gave the front panel a clean, its looking better already

[Steve G4WCS]

Had it under power firstly via a lamp limiter. It isn't well. Was making different noises on different bands, and the RF and AF gain controls seem to work but no reception. C86 has certainly seen better days though. Some wiring has either been replaced or modified, and the BFO switch has been replaced with a rotary switch and lots of wiring. Also has diode rectifiers fitted. Oh and the dial string has come off.

[Steve G4WCS]

BFO switch

[Silicon]

Is that valve next to the voltage regulator a double triode?

A previous owner may have added a product detector.

[Steve G4WCS]

Originally Posted by Silicon

Is that valve next to the voltage regulator a double triode?

A previous owner may have added a product detector.

Good shout it's an ECC83

[CambridgeWorks]

Those black knobs you removed are Pye Telecom ones, used on the RTC teak cased remote controller amongst other gear.
Can be quite sought after. Heavy, solid construction, brass insert and 4BA grub screw. Far more common in light blue on mobiles up to 1967 or so.
Rob

[Steve G4WCS]

Originally Posted by robinshack

Those black knobs you removed are Pye Telecom ones, used on the RTC teak cased remote controller amongst other gear.
Can be quite sought after. Heavy, solid construction, brass insert and 4BA grub screw. Far more common in light blue on mobiles up to 1967 or so.
Rob

Thanks I've put a post up in for sale on the off chance someone on here wants them

[CambridgeWorks]

Hi Steve, I think that offer is extremely optimistic!
Blue ones, though more numerous BACK IN THE DAY are the only ones that fit in with the "Police Radio" style renaissance much sought after these days. Blue ones, in a good, non faded condition, maybe only worth 2 or3 pounds each to such an enthusiast.
Black, although quite scarce, (maybe produced as little as 1 in100 compared with blue) have very little use to such enthusiasts.
Rob

[Steve G4WCS]

I've managed to successfully put the dial string back by removing the oscillator cover, phew. C64 looks like it's had it. Is it worth replacing with a silver mica re https://youtu.be/G3-O_nSabd0

[Steve G4WCS]

Or I have a 12pf 200v mil spec ceramic ?

[Silicon]

C64 may have been chosen for its temperature coefficient.

It may compensate for the change in frequency of the rest of the circuit with temperature changes.

[turretslug]

I agree, it could well be a tempco component. It may look a bit manky, but that could just be the effect of long-term humidity on the paint. Those low-capacitance tubular ceramics are generally very reliable, though there could always be exceptions six decades on!

[Steve G4WCS]

Fair point, I had thought about temp coefficient. Will inspect more closely I thought it was metallisation that had flaked off and not paint

[Radio Wrangler]

Conversely, the tempcos of other related components may have been chosen to compensate for it.

Compensation is a two-way street.

David