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Fog Tripper posted:Going to give the home-brewed magnetic loop antenna a shot when time allows. For now I have a wire lopped around a west-facing window (inside) and get a handful of SW stuff at night. I suspect being in a valley surrounded by honking huge mountains may block a smidge of the signals. The mag loop will probably do wonders for you, and it'll only take an afternoon to build.
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Jan 13, 2013 04:16
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AstroZamboni posted:The mag loop will probably do wonders for you, and it'll only take an afternoon to build. Snagged a very nice boom box at the thrift store, which will replace the one I canibalized from my work bench. $8 Picked up 12' of the 1/4" copper tube @ $2 a foot. Figured on cutting it to size. Probably the most expensive part. I have a soldering iron en route from Amazon. I have a few projects occurring right now (school, selling stuff on ebay and a large minecraft build.  ), but am excited about getting started on the mag loop when time allows. It will be limited to sitting in my ground floor office window.
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Jan 13, 2013 16:49
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I'm back in the game! It's cold, and winter is a good time to play radio. I built a simple L-network random wire tuner in an ATX PSU case for my Icom, and am going to reroute the feedline to my old 75m dipole to the bedroom window. It's just a casual Radio Habana/broadcast AM dialspin setup, nothing too intense. And it all got driven by me finding an XBOX 360 PSU and noting that it delivered 12v @ 16 amps, hacking it to be a general purpose PSU and then thinking about what I could use 12 volts at 16 amps for.
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Jan 15, 2013 23:08
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Oh my god I never knew soldering would be this difficult. I am holding the solder in contact with what I want attached, wire is touching the contacts, etc... and the moment the solder melts, it rolls right off and falls to the countertop. What am I missing?
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Jan 20, 2013 05:48
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Is the tip of the iron clean? I would get that problem with a dirty tip. Coating the tip with solder and wiping it with a damp sponge is a good way to clean it.
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Jan 20, 2013 14:16
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It's burgin' time! 
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I heart bacon posted:Is the tip of the iron clean? I would get that problem with a dirty tip. Coating the tip with solder and wiping it with a damp sponge is a good way to clean it. Brand new iron. It's the wire and contact that is not holding the solder.
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Jan 20, 2013 16:24
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Try sanding the wire and contact.
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Jan 20, 2013 18:43
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AstroZamboni posted:Try sanding the wire and contact. They are really really really tiny, and the connection from the block to the copper tubing is braided, so... I gave up on the latter and wrapped the braid well around the copper and electrical taped it.
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Jan 20, 2013 19:46
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Would flux help?
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Jan 21, 2013 01:22
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Vir posted:Would flux help? I don't know  Flux is to help draw solder into pipe joins, yes?
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Jan 21, 2013 03:34
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Fog Tripper posted:I don't know When soldering copper pipe fittings the solder is drawn into the joint by capillary action. I'm guessing (and I could very well be wrong) the reason you're having difficulty getting the solder to stick is because you're just trying to melt the solder and not actually heating the two parts to be joined enough.
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Jan 21, 2013 03:48
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You will not be able to get 1/4" copper tubing to solder temp with anything less than a 100 watt iron, and it would be extreme pain to try it with that. Easiest would be to get a $8 propane torch head from Home Depot or Harbor Freight, though a $10 butane pencil torch will do the job and is a bit more nimble, for future use. I use mine all the time. When building mag loops, it is extremely important that you get all the connections very, very low resistance. The loop has radiation resistances of fractions of an ohm, so if you have 0.1 ohm resistance at one of your connections, there's half of your power right there. Are you following a howto or guide, or just kind of whipping this up?
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Jan 21, 2013 16:07
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Jonny 290 posted:You will not be able to get 1/4" copper tubing to solder temp with anything less than a 100 watt iron, and it would be extreme pain to try it with that. Following the mag loop how-to linked in the OP. I am completely clueless when it comes to electrical terms. Could you explain in layman's terms about the ohm resistance and how it is best to be making these connections in that light?
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Jan 23, 2013 19:21
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Fog Tripper posted:Following the mag loop how-to linked in the OP. OK, great! It's a simple and tested design. Antennas have a 'radiation resistance', which is a property of them that makes them appear (to a power source of a specific frequency) as being simply a big old resistor of a certain value. This has nothing to do with resonance, but is sort of related to size (although it's not just a linear relationship). An antenna can have one ohm or a thousand ohms of radiation resistance at resonance, or at any point off resonance, depending on its design. Loop antennas are very very small as a function of wavelength, and their radiation resistance is very low. Like, less than one ohm. This means that any resistances in the actual antenna circuit ( ohmic losses - like skinny copper wires or bad connections) dissipate a non-trivial fraction of your incoming signal. If you have an antenna with one ohm radiation resistance, and the connections have 10 ohms of resistance, only ~1/10th of the signal the antenna is receiving is actually going to appear as a voltage - the rest is going to be literally burnt up as (a tiny amount of) heat. Your two big connections to pay attention to are the two connections on the big loop, between each end and a side of the tuning cap. At the very least, you want to attach some sort of terminals to the ends of the pipe, or flatten it and drill a hole, then run a screw through to the capacitor terminal. Crimping and soldering is best, followed by just (solidly) crimping, followed by soldering. Basically, do not just twist the wires on or use skinny little jumper leads to connect the tubing to the capacitor. Going to extreme measures isn't going to mean the difference between white noise and hearing a mouse fart, but it is always the right thing to do to "build it once and build it right."
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Jan 24, 2013 01:23
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Jonny 290 posted:OK, great! It's a simple and tested design. Perhaps I can take the two coper tube ends out of where they are a fixed on the shaft, insert the braided wire into the ends, crimp the tube onto the braid, then apply some gobs of solder to the join after I heat it up well with the kitchen torch. edit: and then attach it to the shaft after routing the braid through the existing holes and out the top to the box. Concerning the tuner box, one of the connections has a very thin copper wire that used to lead to the internal part of the radio where the thin wire was wrapped around a bazillion times. Would that have been the AM antena? Rather than remove the thin copper wire entirely, I used it to connect the other points on the box. Too thin? Should I remove it and use thicker? If I remove the piece of plastic I mounted the box to and start over with the box connections, a) what material is best for the board (and can I get it from Amazon) and b) to solder it properly will I need the 100 watt iron? Kitchen torch may have an averse effect on the tuner box. edit:  
Fog Tripper fucked around with this message at 02:42 on Jan 24, 2013 |
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Jan 24, 2013 02:20
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The braid idea is spot on. You've got the right idea. What I would do is to flux and tin the ends of the copper tubing with a torch away from the capacitor, and then crimp it up and finish by soldering it where the braid goes into the tube with your 100 watt iron. If you have a pair of forceps or a small pair of needlenose pliers and a rubber band, clamp it on the braid near the capacitor as you solder - it'll heatsink a lot of excess heat away and help protect your cap. You won't need a big globby solder joint,just enough to fill in between the contour of the end of the tube and the braid, to make a good solid connection. The bulk of your connection will be actually in the crimped part. Don't try to tin the inside of the tube all the way in or anything, you just want bare copper on that crimp. The long wire wrapped around the rod is indeed the AM antenna. That rod is made of ferrite, which makes for very high inductance coils when you wrap wire around it. I would not use it for hookup wire, it is especially fragile and thin. You want to make sure to get the correct two connections on the capacitor. The terminals should NOT have DC continuity between them. Make sure you hit the terminals with a multimeter, and if you get any resistance other than 'infinity', either the capacitor has touching plates (unlikely) or it's just two terminals for the same set of plates, and the antenna won't work. If you have any more of that braid, try to solder a short piece on to the other terminal, so your connections are the same. If you don't, you can go buy a small spool of desoldering braid at an electronics store, which is the exact same thing. Then you also have desoldering braid for future projects! Your mounting plate seems to be okay but you may see a little bit of detuning when you move your hand near it - at certain settings you may need to 'tune past' with your hand on the dial, so that it's on frequency when you pull your hand away. A small metal plate may assist in this. I would only worry about this if you get this thing built and it works, but you get too annoyed from detuning effects. We can deal with that later. E: Here's a link to the little antenna tuner I mentioned above; it's not really related to your project but it shows you what a nice air variable capacitor looks like, which you should keep an eye out for. If you can find any old tube or non-portable radio that covers AM older than about 1975 or so, it will have one of them in there. Even if the radio's dead, that capacitor will cost you ten bucks online easily. if the radio costs $5, get it just for the cap. A capacitor like this will have less loss and better range than the one you're currently using; if you're going to have fun with loops, you should try to get a few different variable caps to play with as you won't want to tear apart one loop to build another. http://jonny290.tumblr.com/post/40652895492 Jonny 290 fucked around with this message at 04:45 on Jan 24, 2013 |
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Jan 24, 2013 04:32
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Jonny 290 posted:
This issue being is that it was/is soldered on to what is not much more than a nub of that specific contact coming out of the box. You can see it in the first picture above. Uncertain how I could get it swapped over to better wire. I really wish it had a full "leg" like the other contacts coming out of the box. I have a proper board and some thinner electronic solder on the way, as well as a pack of wire jumpers to use with the board. Looking back at the current setup (especially in the closeup pictures) it looks a mess. Redoing it (perhaps with a different box) will give me a chance to do the connections from tube to braid without worry about heat. Is there a concern about the length of the braid between the tube connect and the box?
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Jan 24, 2013 05:18
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Hmm. I see what you're saying. Just keep the lead as short as you can, and crimp/solder it best you can. You're working with junkbox parts, after all, so you might need to fudge a bit. As long as those leads are shorter than a couple inches, you won't see serious problems.
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Jan 24, 2013 20:36
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Two pieces of SDR software I've been messing with a little lately:quote:SDR Touch: An Android-based software defined radio On HF I've been playing with glSDR (and the Windows version too)... I was listening to a receiver in Europe last night and it's been a long time since I've heard so many different stations coming in so clearly.
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Feb 1, 2013 23:26
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nmfree posted:Two pieces of SDR software I've been messing with a little lately: Would http://www.amazon.com/Receiver-RTL2832U-Compatible-Packages-Guaranteed/dp/B009U7WZCA be a good option for attaching to a smartphone for the above-mentioned android sdr?
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Feb 2, 2013 17:37
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Fog Tripper posted:Would http://www.amazon.com/Receiver-RTL2832U-Compatible-Packages-Guaranteed/dp/B009U7WZCA be a good option for attaching to a smartphone for the above-mentioned android sdr? The dongle I'm using is this one from DealExtreme (also available on eBay). If you really want to go cheap, you could try this one, although the only picture doesn't show an external antenna jack (one is listed in the specs, but still). Also, if anyone is too lazy to build an HF upconverter for their dongle you can now buy one already built on Amazon.
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Feb 2, 2013 22:11
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Is the list of recommended radios in the OP still accurate? Also what stores still carry shortwave radios? I checked at Best Buy, Target, and Bed Bath & Beyond (someone mentioned getting one there somewhere in the first few pages).
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Feb 4, 2013 04:10
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Account_Username posted:Is the list of recommended radios in the OP still accurate? Also what stores still carry shortwave radios? I checked at Best Buy, Target, and Bed Bath & Beyond (someone mentioned getting one there somewhere in the first few pages). I got mine at Cabela's, if you have one of them near you. They probably won't have them for less than MSRP though.
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Feb 4, 2013 04:24
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You can also get some great deals on receivers over on QRZ and eHam in their swapmeet sections. Don't rule out an older transceiver, I've got an old Kenwood that runs rings around any Grundig I've ever tried. Nothing says you have to TRANSMIT on it, after all.
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Feb 4, 2013 05:01
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Radio Shack usually has Grundig G3s. At least all the ones near me do.
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Feb 4, 2013 06:06
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97bux later, I have a shiny new radio. I'm also pretty sure this is the only time I've bought anything radio related at Radio Shack.  
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Feb 4, 2013 18:33
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Man, I can remember when we used to hack beat frequency oscillators into our AM-only shortwave radios so we could tune SSB, because even the Sangean ATS-803A was $200. Under a hundo for an SSB receiver is great.
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Feb 4, 2013 19:47
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Able to pick up a few stations so far. I can get radio Cuba at night on 6165k, and I found a Chinese station somewhere in the low 13mhz freqs. Right now I'm listening to a crazy-rear end preacher on 9980k.
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Feb 6, 2013 15:50
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I'm just getting back into playing with my radio after a fairly long hiatus. Anyone else really amazed that this thread is almost 6 years old?
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Feb 6, 2013 20:12
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Account_Username posted:Able to pick up a few stations so far. I can get radio Cuba at night on 6165k, and I found a Chinese station somewhere in the low 13mhz freqs. Right now I'm listening to a crazy-rear end preacher on 9980k. If you tune between 7100 and 7300 LSB in the evenings, you are almost guaranteed to pick up some hams chatting away on 40 meters. Don't be surprised if you can only hear one side well.
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Feb 6, 2013 20:34
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Accursed posted:I'm just getting back into playing with my radio after a fairly long hiatus. Anyone else really amazed that this thread is almost 6 years old? Nobody's more amazed than I am, bub.
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Feb 7, 2013 04:22
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Anyone else still using the #shortwave channel on IRC?
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Feb 7, 2013 06:35
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Accursed posted:Anyone else still using the #shortwave channel on IRC? I'm just idling in #hamradio now.
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Feb 18, 2013 23:15
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I'm glad to see this thread is still A Thing. I read the entire thing over the course of a few days and I really want to get a radio. Probably going to find a G3 somewhere, but I'm also interested in going down the SDR route, since frequency range is pretty good on those, but I think I'll start off cheap and just get a G3.
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Feb 24, 2013 08:10
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I got my first broadcast QSL card today, from Radio Romania International. It's neat that they keep it up.
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Feb 24, 2013 18:36
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Accursed posted:I'm just getting back into playing with my radio after a fairly long hiatus. Anyone else really amazed that this thread is almost 6 years old? This was the thread that got me to register for SA. I lost it when it left GBS (and haven't fired up the Grundig for almost as long), but may have to get back into it one evening.
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Feb 25, 2013 05:14
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I have a head-unit in my car that does shortwave, my regulars are usually Radio Australia in the morning and BBC for Africa driving home. I do check WBCQ and the DXing shows on WWCR weekends. The other day doing a scan I freaked my wife out when it stopped on a Cuban numbers station. Also noticed the Cubans have gone digital, in-between the usual sets of numbers read by the mechanical-sounding female you get a digital hash. Anyone ever try decoding it?
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Feb 25, 2013 17:02
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Radio Nowhere posted:I have a head-unit in my car that does shortwave, my regulars are usually Radio Australia in the morning and BBC for Africa driving home. I do check WBCQ and the DXing shows on WWCR weekends. The other day doing a scan I freaked my wife out when it stopped on a Cuban numbers station. Also noticed the Cubans have gone digital, in-between the usual sets of numbers read by the mechanical-sounding female you get a digital hash. Anyone ever try decoding it? Please tell me you have a Phillips DC777. I've wanted one of those for like twenty years, even before I could drive.
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Feb 25, 2013 17:42
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Jonny 290 posted:Please tell me you have a Phillips DC777. Nope, mine's a Sony that has a CD player and USB!  https://www.youtube.com/watch?v=tAbaUZINLp8
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Feb 25, 2013 18:01
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So anybody going to see "The Numbers Station" movie when it comes out? http://movies.yahoo.com/video/numbers-station-trailer-231249002.html
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Feb 28, 2013 04:59
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