17-01-2016, 09:46 PM
These are nice old things. Dark brown body with vivid colours that are easily seen with the naked eye and are nigh-on impossible to mis-read. Unlike the modern metal-film types with the light-blue body. Whoever chose that colour needs to explain themselves! The Mullard dark greens were better, but only a bit. And of course, with the addition of the 5th band - invariably black, of course - it means that the multiplier has dropped by one, with the net result that circuit boards are a less colourful, less beautiful thing to behold. Let's not even consider SMT!
Silly, I know, but as a kid, I really loved the pictures in the Ladybird books. As I've said before, my favourites were the deep red/maroon body types from Piher. If you wish to indulge, see here: http://www.mds975.co.uk/Content/george_d...radio.html - page 39 is probably my favourite. The real book is better than the scans, naturally. Just lovely...
Back to the radio, another common problem with these is poor sensitivity on FM. Usually caused by Lockfit transistors, but I can't help wondering if the resistors could in-part be responsible. The noise seems to be the 1/f type - not that I've taken rigorous measurements so far - so perhaps at 10.7MHz it might not be an issue. It's fair to say that I must have serviced at least 50 of these over the last 5 years, and the spread of sensitivity is at least 30dB. Clearly, I can't be curing all the maladies on the worst of them, and I'm sure that the 2 or 3 that were exceptional were flukes, but there's clearly something going on. Supply voltage to the RF and IF stages is important, and often carbon-comps that have drifted high are part of that problem.
By comparison, the other FM sets from Hacker - the Sovereigns and VHF Heralds - are much more consistent and reliable. Clearly something in the design of this set was a bit marginal. Not a problem for most owners, but we're in a dreadful reception area for FM here. My bedside radio was Jeffrey's VHF Herald (one of my earliest restorations) until an accident resulted in a broken aerial at Christmas, so I'm using a Hunter instead at the moment. I'm forever having to tweak the position of the aerial to get half-decent reception. Anyone have a spare VHF Herald aerial?
Silly, I know, but as a kid, I really loved the pictures in the Ladybird books. As I've said before, my favourites were the deep red/maroon body types from Piher. If you wish to indulge, see here: http://www.mds975.co.uk/Content/george_d...radio.html - page 39 is probably my favourite. The real book is better than the scans, naturally. Just lovely...
Back to the radio, another common problem with these is poor sensitivity on FM. Usually caused by Lockfit transistors, but I can't help wondering if the resistors could in-part be responsible. The noise seems to be the 1/f type - not that I've taken rigorous measurements so far - so perhaps at 10.7MHz it might not be an issue. It's fair to say that I must have serviced at least 50 of these over the last 5 years, and the spread of sensitivity is at least 30dB. Clearly, I can't be curing all the maladies on the worst of them, and I'm sure that the 2 or 3 that were exceptional were flukes, but there's clearly something going on. Supply voltage to the RF and IF stages is important, and often carbon-comps that have drifted high are part of that problem.
By comparison, the other FM sets from Hacker - the Sovereigns and VHF Heralds - are much more consistent and reliable. Clearly something in the design of this set was a bit marginal. Not a problem for most owners, but we're in a dreadful reception area for FM here. My bedside radio was Jeffrey's VHF Herald (one of my earliest restorations) until an accident resulted in a broken aerial at Christmas, so I'm using a Hunter instead at the moment. I'm forever having to tweak the position of the aerial to get half-decent reception. Anyone have a spare VHF Herald aerial?
