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Anyone modified a Tecsun PL-390?
Michael Black wrote in
news:alpine.LNX.2.02.1409062303070.10573@darkstar. example.org: IN the old days, they'd either suggest wrapping some wire around the radio, grounding one side and the other going to the antenna. In other words, a inductive coupling loop to the loopstick. The advantage of this method is that it requires no modification, the disadvantage is that it looks messy and may interfere with the controls. So you open up the radio and put a few turns on the loopstick, grounding one end and the other going to the antenna. It's the same thing, but no messy outside loop (and in the case of a digitally tuned radio, winding directly on the loopstick likely adds less noise than a winding around the radio (which might pick up the noise from the radio). Thankyou! I liked that idea so much I went without sleep and had at it. I have no photo hosting but I'm willing to upload a picture of the doings if there's a way to make it generally useful. I now have a little over 100 turns of enamelled copper wire (a thickness chosen to allow good current for lowest loss) on one end of the PL-390's ferrite bar. One end is grounded, the other, after laying two layers of turns around the rod in the same direction as the main winding, is soldered to the unused middle connection of the 3.5mm RF input jack. The result is excellent too, despite the huge amounts of ambient noise from computer, router, modem, LCD touchscreen and all, I'm getting every NDB I have detected with the single exception of the ghostly Southhampton 15nm range one. I thought I'd lost Gloucestershire too but apparently it has changed frequency a tad, and it's definitely there, clear if not strong. Once I get a chance to run a longwire out on Ashton Court I think I might hear London Calling... (Good album, that though I prefer X-Ray Spex. Never mind, long story...) Anyway, this is in the city centre, close to sea level, using the 8m tall external whip. I think once I get it tested out on open land 125m above sea level with a longwire it will be a great deal more interesting than it was out there before. It does make me wonder what is done in the average shortwave portable. EIther the external antenna connector doesn't work on the AM broadcast and LW bands, or they use some other scheme to couple to the rest of the receiver on those bands. I don't have that sort of schematic handy. The PL-390 does it by switching the local telescopic whip out of circuit when the remote antenna jack is plugged in. The unused middle terminals would be equally capable of this, but they're soldered together and I left them that way, other than adding my own wire from the new coil. Neither the whip or the external antenna socket are used by the AM wavebands (MW+LW with a remarkably small gap where the emergency shipping signals used to be at around 500 KHz). I think there are two separate inputs to the DSP IC, one for these AM bands, and another for HF and VHF. It might be even more complex, but I don't know. I want to avoid taking the radio apart any more than I did, it's extremely fragile... The internal loopstick needs to stay as it is, since it's not just "an antenna", but the tuned circuit at the front of the radio. Unless you were going to get really fancy, and change the loopstick for a shielded coil fo the same inductance, and then coupled the antenna to that. Agreed. The shielded inductor is a nice idea, but the first idea is best for me, as it does not compromise intended operation in any way all, but adds a great deal to the PL-390's AM capability. Whether more or less turns than my 100 (approx..) would be better I'm not sure but I didn't see any signs of overload when checking the Bristol airport NDB, and either it's not at all critical, or I got lucky. What IS critical is a good ground... Or, use a big external loop of the same inductance, and use that instead of the internal loop, though in that case, it won't be so portable, and you wouldn't want to have the loop any distance from the radio. I think that's what the people discussing the Laurie Mann modification were doing, but I didn't get enough of the original context to be sure. One guy was certainly doing something with a 4' loop built using 1.5'' UPVC pipe. Not as portable as I want. It could be great if I want to explore external tuning though. (And a good excuse to use some very nice tuning capacitors.) My original plan was to try a larger ferrite rod and coil, something more like the multi-layered turns I've seen on old receivers, but tonight's work has left me satisfied for now, and likely for some time, it will take several attempts to figure out how far it will go. In short, I think the Tecsun PL-390's LW AM performance is a LOT better than it is credited for generally, but all the same I'd like to have a crack at seeing if I can hear an NDB from london to Bristol. I know, little things please little minds. But it's a very fun way to learn so I want to have at it, and I'm interested in anything anyone has to say if they have worked on modifying this specific radio in any way. The only reviews I've seen of that sort of radio are from here in North America. An important consideration is that there is no long wave broadcasting over here, so the LW band is mostly dead. The only thing left down there is some airport beacons. I havent' spent much time tuing LW, but all I've heard is the local airport beacon (and maybe the Ottawa beacon, I wasn't completely sure). That was with a Grundig YB400, shrotwave portables are the only LW receivers I've ever had. Apparently there are submarines, but only at around 30 KHz. Things are allegedly better for US LW DX if you can get to an ocean. I read a web page that suggested it might be more exciting than I can know. Having lots of LW transmissions isn't the boon it might seem, the big ones swamp the band so much the allocation is pretty much one per nation in Europe, though France has three! Maybe you also get something I know of here but have not explored, there's some kind of digital modulation at around 100 KHz (carrier) for logistical stuff for roads and weather, for hauliers and such. Also MSF time at 60 KHz but that's beyond any receiver I've had for a long time. By the way, my dad had a Grundig Yacht Boy 210, an ancestor of your YB400. I identified with it more closely than if it had been a family pet. It was central to home life, we had no TV... Got to say I liked the Hacker radios better though, for general listening. I intend to make a cabinet to mount the PL-390, for home use, better sound, larger NiMH cells, etc. Sonically, it's surprisingly close to hi-fi on VHF. I think it just might be the best all-rounder receiver ever designed for mass marketing and low cost. |
#2
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Anyone modified a Tecsun PL-390?
On 07/09/14 19:06, Lostgallifreyan wrote:
Once I get a chance to run a longwire out on Ashton Court I think I might hear London Calling... (Good album, that though I prefer X-Ray Spex. Never mind, long story...) Great, now I've got that song in my head. (And yes, I've got that album on LP too.) I see I'll be giving that song and a few others on that album a flogging when I get to work tomorrow. Still, good to hear you've got your set suitably modified and working. Not sure if that set does SSB (doesn't look like it) but it looks like a handy little receiver. |
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Anyone modified a Tecsun PL-390?
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Anyone modified a Tecsun PL-390?
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#5
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Anyone modified a Tecsun PL-390?
On 07/09/14 10:06, Lostgallifreyan wrote:
Michael Black wrote in news:alpine.LNX.2.02.1409062303070.10573@darkstar. example.org: IN the old days, they'd either suggest wrapping some wire around the radio, grounding one side and the other going to the antenna. In other words, a inductive coupling loop to the loopstick. The advantage of this method is that it requires no modification, the disadvantage is that it looks messy and may interfere with the controls. So you open up the radio and put a few turns on the loopstick, grounding one end and the other going to the antenna. It's the same thing, but no messy outside loop (and in the case of a digitally tuned radio, winding directly on the loopstick likely adds less noise than a winding around the radio (which might pick up the noise from the radio). Thankyou! I liked that idea so much I went without sleep and had at it. I have no photo hosting but I'm willing to upload a picture of the doings if there's a way to make it generally useful. I now have a little over 100 turns of enamelled copper wire (a thickness chosen to allow good current for lowest loss) on one end of the PL-390's ferrite bar. One end is grounded, the other, after laying two layers of turns around the rod in the same direction as the main winding, is soldered to the unused middle connection of the 3.5mm RF input jack. The result is excellent too, despite the huge amounts of ambient noise from computer, router, modem, LCD touchscreen and all, I'm getting every NDB I have detected with the single exception of the ghostly Southhampton 15nm range one. I thought I'd lost Gloucestershire too but apparently it has changed frequency a tad, and it's definitely there, clear if not strong. Once I get a chance to run a longwire out on Ashton Court I think I might hear London Calling... (Good album, that though I prefer X-Ray Spex. Never mind, long story...) Anyway, this is in the city centre, close to sea level, using the 8m tall external whip. I think once I get it tested out on open land 125m above sea level with a longwire it will be a great deal more interesting than it was out there before. It does make me wonder what is done in the average shortwave portable. EIther the external antenna connector doesn't work on the AM broadcast and LW bands, or they use some other scheme to couple to the rest of the receiver on those bands. I don't have that sort of schematic handy. The PL-390 does it by switching the local telescopic whip out of circuit when the remote antenna jack is plugged in. The unused middle terminals would be equally capable of this, but they're soldered together and I left them that way, other than adding my own wire from the new coil. Neither the whip or the external antenna socket are used by the AM wavebands (MW+LW with a remarkably small gap where the emergency shipping signals used to be at around 500 KHz). I think there are two separate inputs to the DSP IC, one for these AM bands, and another for HF and VHF. It might be even more complex, but I don't know. I want to avoid taking the radio apart any more than I did, it's extremely fragile... The internal loopstick needs to stay as it is, since it's not just "an antenna", but the tuned circuit at the front of the radio. Unless you were going to get really fancy, and change the loopstick for a shielded coil fo the same inductance, and then coupled the antenna to that. Agreed. The shielded inductor is a nice idea, but the first idea is best for me, as it does not compromise intended operation in any way all, but adds a great deal to the PL-390's AM capability. Whether more or less turns than my 100 (approx..) would be better I'm not sure but I didn't see any signs of overload when checking the Bristol airport NDB, and either it's not at all critical, or I got lucky. What IS critical is a good ground... Or, use a big external loop of the same inductance, and use that instead of the internal loop, though in that case, it won't be so portable, and you wouldn't want to have the loop any distance from the radio. I think that's what the people discussing the Laurie Mann modification were doing, but I didn't get enough of the original context to be sure. One guy was certainly doing something with a 4' loop built using 1.5'' UPVC pipe. Not as portable as I want. It could be great if I want to explore external tuning though. (And a good excuse to use some very nice tuning capacitors.) My original plan was to try a larger ferrite rod and coil, something more like the multi-layered turns I've seen on old receivers, but tonight's work has left me satisfied for now, and likely for some time, it will take several attempts to figure out how far it will go. In short, I think the Tecsun PL-390's LW AM performance is a LOT better than it is credited for generally, but all the same I'd like to have a crack at seeing if I can hear an NDB from london to Bristol. I know, little things please little minds. But it's a very fun way to learn so I want to have at it, and I'm interested in anything anyone has to say if they have worked on modifying this specific radio in any way. The only reviews I've seen of that sort of radio are from here in North America. An important consideration is that there is no long wave broadcasting over here, so the LW band is mostly dead. The only thing left down there is some airport beacons. I havent' spent much time tuing LW, but all I've heard is the local airport beacon (and maybe the Ottawa beacon, I wasn't completely sure). That was with a Grundig YB400, shrotwave portables are the only LW receivers I've ever had. Apparently there are submarines, but only at around 30 KHz. Things are allegedly better for US LW DX if you can get to an ocean. I read a web page that suggested it might be more exciting than I can know. Having lots of LW transmissions isn't the boon it might seem, the big ones swamp the band so much the allocation is pretty much one per nation in Europe, though France has three! Maybe you also get something I know of here but have not explored, there's some kind of digital modulation at around 100 KHz (carrier) for logistical stuff for roads and weather, for hauliers and such. Also MSF time at 60 KHz but that's beyond any receiver I've had for a long time. By the way, my dad had a Grundig Yacht Boy 210, an ancestor of your YB400. I identified with it more closely than if it had been a family pet. It was central to home life, we had no TV... Got to say I liked the Hacker radios better though, for general listening. I intend to make a cabinet to mount the PL-390, for home use, better sound, larger NiMH cells, etc. Sonically, it's surprisingly close to hi-fi on VHF. I think it just might be the best all-rounder receiver ever designed for mass marketing and low cost. ============= Talking LW time signals ,the UK MSF 60kHz tx is now located at Anthorn -Cumbria . Sig here in Scotland is pretty strong. It is a bit different with DCF at 77 KHz located near Frankfurt a/M -Germany . Both Lidl and Aldi (supermarkets) sell radio controlled clocks on 77KHz, but to get the radio time signal I have to place such a clock near the window here in the north of Scotland (IO87AT) A reliable signal seems to be available everywhere up to approx 1000 kms from the tx Do you receive DCF ,77 khz well on your rx ? Frank , GM0CSZ Frank GM0CSZ |
#6
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Anyone modified a Tecsun PL-390?
highlandham wrote in news:lui1dh$ku0$1@dont-
email.me: Talking LW time signals ,the UK MSF 60kHz tx is now located at Anthorn -Cumbria . Sig here in Scotland is pretty strong. It is a bit different with DCF at 77 KHz located near Frankfurt a/M -Germany . Both Lidl and Aldi (supermarkets) sell radio controlled clocks on 77KHz, but to get the radio time signal I have to place such a clock near the window here in the north of Scotland (IO87AT) A reliable signal seems to be available everywhere up to approx 1000 kms from the tx Do you receive DCF ,77 khz well on your rx ? I wish I could.. Neither of my radios will do it. 100KHz on the AOR AR-3000 is as low as it gets here. Maybe some frequency doubling relay can exist that would allow down to 50 KHz reception... Over a decade ago when I was looking at MSF based on a Maplin kit or two, the transmissions were still from somewhere further south than now, not sure where, they'd just changed from Rugby a few years earlier. Teddington maybe? Reception was awkward, very fussy inside a basement, but it worked. |
#7
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Anyone modified a Tecsun PL-390?
There's an Ultralite group on Yahoo. They do a lot with cobbling in
loops, etc to such radios. I haven't checked-in in a long time since back when I had a PL-380. They have tallied up some good results as a group are knowledgeable about the tuning system in that series or radios. -Bill |
#8
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Anyone modified a Tecsun PL-390?
Bill M wrote in :
There's an Ultralite group on Yahoo. They do a lot with cobbling in loops, etc to such radios. I haven't checked-in in a long time since back when I had a PL-380. They have tallied up some good results as a group are knowledgeable about the tuning system in that series or radios. I think they might be the source of what I found. I used to have access to Yahoo until BT changed the login for emails to their own hosts. Right now I doubt I have access, and Yahoo insist on policing me to use the latest browser to access their walled garden (and by default and direct follow-on) the latest Windows OS too, to support it! All this to access what is basically a text discussion with a bit of picture hosting. Now, if any of them read this and are willing to post on Usenet which is a much better medium for the subject, I'm totally content. The alternative is to do without as a result of my stand in not yielding to the fabricated urge that drives so many people to accept systems aimed at satisfying those who do not know anything about simple efficiency, at the expense of all those who do. I could live with that, but I'd rather encourage people to use Usenet. It's obituaries grow many and old, while it continues to thrive. |
#9
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Anyone modified a Tecsun PL-390?
Lostgallifreyan wrote:
Bill M wrote in : There's an Ultralite group on Yahoo. They do a lot with cobbling in loops, etc to such radios. I haven't checked-in in a long time since back when I had a PL-380. They have tallied up some good results as a group are knowledgeable about the tuning system in that series or radios. I think they might be the source of what I found. I used to have access to Yahoo until BT changed the login for emails to their own hosts. Right now I doubt I have access, and Yahoo insist on policing me to use the latest browser to access their walled garden (and by default and direct follow-on) the latest Windows OS too, to support it! All this to access what is basically a text discussion with a bit of picture hosting. Now, if any of them read this and are willing to post on Usenet which is a much better medium for the subject, I'm totally content. The alternative is to do without as a result of my stand in not yielding to the fabricated urge that drives so many people to accept systems aimed at satisfying those who do not know anything about simple efficiency, at the expense of all those who do. I could live with that, but I'd rather encourage people to use Usenet. It's obituaries grow many and old, while it continues to thrive. Ohhh. That's quite a conundrum my friend. An alternative might be to contact Jim Kearman, KR1S, over on the Radio Board Forum. He's a ringmaster with the Ultralights and I'm sure would be happy to share his insights. http://theradioboard.com/rb/index.php I'll save my comments on the demise of Usenet. -Bill |
#10
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Anyone modified a Tecsun PL-390?
Bill M wrote in :
Ohhh. That's quite a conundrum my friend. I have no special thoughts on Usenet actually, I just find that Yahoo makes life harder for me, not easier. Like water, I find it hard to go uphill. Thanks for the info about Jim Kearman, very helpful. |
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