Thanks Tony, and everyone else for your interest, advice and encouragement.
It's all systems go!
I wired the coil with the 4R winding for MW, and the 24R coil in series for LW, with the 70R winding for coupling. I used the same phase (start and finish of the windings) as with the aerial coil, and bingo, the radio burst into life! It performs much better than I'd expected, with excellent volume on just a few feet of wire for an aerial. It's selective, and lots of stations on MW and two or three on LW. The 'volume control/reaction' works just like a normal volume control and isn't touchy to adjust. Unless you knew, you wouldn't know it's a TRF rather than a superhet.
I've not checked the accuracy of the dial compared to the stations, and as I said earlier, I don't have any alignment info, but I'll see what data for similar TRF sets such as Champions say.
I checked the inductance of the various windings on the repaired coil, albeit I’ve no doubt that the phantom fidler who crawled all over this set before it came my way, will have fiddled with the cores of the coil. For what it's worth, the inductances were: MW 166uH, LW, 2.2015 mH, and the coupling coil 10.25mH. Taking the lazy route, I used a resonant frequency calculator, and judging by the size of the tuning cap, I made an assumption that it was about 365pF. (There doesn't look to be enough vanes on it for it to be 500pf, but more vanes than would suggest much lower than 365pF). Using that assumption, this would put the lower end of the MW at 461 Metres, (0.646mHz), and the lower end of LW at 1,694M (0.177mHz). Given that it's a TRF, no doubt if I loose couple my frequency counter to the coil, I could ascertain the actual frequency and tweak the cores and trimmers to line it up with the dial.
The calculator I used for the resonant frequency, and frequency/wavelength converter were:
Resonant Frequency Calculator:
http://www.deephaven.co.uk/lc.html
Frequency to wavelength converter:
http://www.translatorscafe.com/cafe/unit...avelength/
Flushed with success, it’s motivated me to get on with using my back panel router jig to make a back for the set, and while I’m at it, to make one for the Noble set I bought at the NVCF, which has an identical cabinet. I'll then write an article for Carl Glover's consideration for the BVWS Bulletin on making radio backs with a router, as I said I would.
I don’t suppose that these sets are rare, but they certainly seem to be uncommon. The only other person I know who has one is Howard Craven, who was most helpful to me in e-mailing me pictures of his Portadyne Princess, including the back panel, and a pic of what the knobs look like as mine came with no knobs. Not only that, Howard tipped me off a short while latter that he’d spotted a couple on e-bay, which I won, and found a third at the NVCF.
I’ve attached a pic of the back which Howard e-mailed to me. (Though original, it looks rather ill fitting, so I’ll make mine fit a bit more snugly, and will make a label with the wording of the original).
It's just occured to me with it being the Diamond Jubille weekend, that this little set left the factory just two years after the Queen's Coronation, a year after I left school, and rationing ended.
All in all, a very successful day, which started with a morning rummage around the Rufforth Autojumble at York, with Colin and Mike Phelan from ‘over the wall’.
Hope that's of interest.
Life is good - I'm going to give myself a pat on the back!
It's all systems go!
I wired the coil with the 4R winding for MW, and the 24R coil in series for LW, with the 70R winding for coupling. I used the same phase (start and finish of the windings) as with the aerial coil, and bingo, the radio burst into life! It performs much better than I'd expected, with excellent volume on just a few feet of wire for an aerial. It's selective, and lots of stations on MW and two or three on LW. The 'volume control/reaction' works just like a normal volume control and isn't touchy to adjust. Unless you knew, you wouldn't know it's a TRF rather than a superhet.
I've not checked the accuracy of the dial compared to the stations, and as I said earlier, I don't have any alignment info, but I'll see what data for similar TRF sets such as Champions say.
I checked the inductance of the various windings on the repaired coil, albeit I’ve no doubt that the phantom fidler who crawled all over this set before it came my way, will have fiddled with the cores of the coil. For what it's worth, the inductances were: MW 166uH, LW, 2.2015 mH, and the coupling coil 10.25mH. Taking the lazy route, I used a resonant frequency calculator, and judging by the size of the tuning cap, I made an assumption that it was about 365pF. (There doesn't look to be enough vanes on it for it to be 500pf, but more vanes than would suggest much lower than 365pF). Using that assumption, this would put the lower end of the MW at 461 Metres, (0.646mHz), and the lower end of LW at 1,694M (0.177mHz). Given that it's a TRF, no doubt if I loose couple my frequency counter to the coil, I could ascertain the actual frequency and tweak the cores and trimmers to line it up with the dial.
The calculator I used for the resonant frequency, and frequency/wavelength converter were:
Resonant Frequency Calculator:
http://www.deephaven.co.uk/lc.html
Frequency to wavelength converter:
http://www.translatorscafe.com/cafe/unit...avelength/
Flushed with success, it’s motivated me to get on with using my back panel router jig to make a back for the set, and while I’m at it, to make one for the Noble set I bought at the NVCF, which has an identical cabinet. I'll then write an article for Carl Glover's consideration for the BVWS Bulletin on making radio backs with a router, as I said I would.
I don’t suppose that these sets are rare, but they certainly seem to be uncommon. The only other person I know who has one is Howard Craven, who was most helpful to me in e-mailing me pictures of his Portadyne Princess, including the back panel, and a pic of what the knobs look like as mine came with no knobs. Not only that, Howard tipped me off a short while latter that he’d spotted a couple on e-bay, which I won, and found a third at the NVCF.
I’ve attached a pic of the back which Howard e-mailed to me. (Though original, it looks rather ill fitting, so I’ll make mine fit a bit more snugly, and will make a label with the wording of the original).
It's just occured to me with it being the Diamond Jubille weekend, that this little set left the factory just two years after the Queen's Coronation, a year after I left school, and rationing ended.
All in all, a very successful day, which started with a morning rummage around the Rufforth Autojumble at York, with Colin and Mike Phelan from ‘over the wall’.
Hope that's of interest.
Life is good - I'm going to give myself a pat on the back!
Regards, David.
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
BVWS Member.
G-QRP Club Member 1339.
'I'm in my own little world, but I'm happy, and they know me here'
