Eddystone HF Receiver 840C

Another day in the Zeta Services play pen, employing my enormous talent, repairing TV after TV for people that don’t realize and appreciate the honour they have bestowed upon them. Then, the monotony was broken when nice customer Paco, Radio Ham extraordinaire came through the door sporting a lovely vintage Eddystone 840C receiver! Paco was presented with the best chair in the office and all other repairs chucked out the door. This set was basically in good order, little hours’ use I would say. All original Brimar valves, all untouched. Powered up the set and left it a while to get comfortable with it’s new surroundings. These sets can take a little while to get to know you, a bit like an abandoned puppy dog. A quick look underside and was happy to see that there were no apprentice marks or previous bodges. The only thing that worried me was the sad view of a sea of Hunts capacitors. If Carlsberg made capacitors, we would all be happy. These capacitors however were the top-end Red coated ones. I snipped a few out to check and, to my horror, they were all perfect, not a Meg Ohm of leakage anywhere. Did my best to set up the local oscillator trimmers for each band so that the dial read correct and trimmed as far as possible. A couple of trimmer caps were a bit scratchy causing the set to jump around. But, given the set is 60 years old and all original, apart from 2 resistors I replaced that were way out, damn bloody good. Now the strange thing is, that this set has no mains transformer, instead, a nice hot dropper resistor. It uses the U series valves with heaters wired in series. All this meaning the chassis is connected direct to one end of the power lead. Guess it would be happy on DC mains as well. In order that the proud owner is not electrocuted by touching the case if the mains plug had been put in the wrong way round, the inner chassis and workings are all isolated from the outside world. A marvel of engineering! Okay, a mains transformer would have put a few more shillings on the price, but the hassle of isolating the inside from the outside would out-weigh that. So if any Radio Ham chaps or chapesses out there can tell me why. Oh, not to forget…No signal strength meter, but a little DM71 exclamation mark magic eye. Sweet.