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The Muffinlord posted:I wasn't planning to use much more than 5 on it; I mostly just want to hear as well as I can be heard without having to use my RTL-SDR for receive audio. But as it turns out, the screw it has for a tripod mount doesn't match the cheap camera tripod I've had lying around for ages, so this may be a wash if I can't get the drat thing mounted properly. It was a wash. I guess I got a defective one, cause it wouldn't mount to a camera tripod more than one single turn without locking up so hard I couldn't turn it with a screwdriver and a wrench, much less by hand. I've returned all the poo poo and I'll do what I should have done anyway, wait for my performance balance from work in like a month and then just buy a really good one from a name brand.
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Feb 5, 2024 18:56
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I'm trying to view the hydrogen line by following this paper as a base, and so far I've got the thing bashed together at least. It was snowing today so I couldn't set it up outside, but it's working well enough to triangulate some spurious emissions on 1419 MHz somewhere on campus. If I want to fine tune things more it sounds like I need a VNA, but I'm not sure which one I should get. NooElec has the NanoVNA H4 and the NanoVNA v2 SAA2 for the same price ($163 CAD), and while it seems like I should just go with the latter because it has a higher frequency range, I'm sure there must be more to it than that which I'm missing. The guys in the microwave lab seem pretty interested in what I'm doing, but I couldn't work up the nerve to ask them if I can hook a piece of cookware up to a $100k Agilent VNA. 
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Feb 14, 2024 04:49
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Coxswain Balls posted:I'm trying to view the hydrogen line by following this paper as a base, and so far I've got the thing bashed together at least. It was snowing today so I couldn't set it up outside, but it's working well enough to triangulate some spurious emissions on 1419 MHz somewhere on campus. If I want to fine tune things more it sounds like I need a VNA, but I'm not sure which one I should get. NooElec has the NanoVNA H4 and the NanoVNA v2 SAA2 for the same price ($163 CAD), and while it seems like I should just go with the latter because it has a higher frequency range, I'm sure there must be more to it than that which I'm missing. It's a tool that analyzes, if they seem interested just ask as the worst is they just nope out. As far as the NanoVNA, it is a nifty lil tool that plays nicely for things like this (just use the software instead of the builtin interface) so that also is an option. Don't know if there are cheaper versions that might work and am now starting to wonder if my "NanoVNA" was even done by Nooelec.
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Feb 15, 2024 01:05
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Coxswain Balls posted:Cookware I have nothing to input in regards to your questions, but I read this article sometime ago and thought it might be useful.
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Feb 15, 2024 10:41
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Thanks for the tips. The one I picked up came in and I've been having fun testing all my antennas. I think I got the hang of it but I'm wondering if I'm missing any critical steps for using it properly. The first time I hooked it up to the radiotelescope I got this reading. That seems way too good to be true for my very first try at building the dipole with a 1/4 wave balun with no measuring tools other than a ruler. The reason I ask if I'm doing it right is because the coax inside the antenna mast broke and I had to rebuild it (didn't have proper strain relief, my bad), and now when I'm testing things my return loss isn't anywhere near as good nor is it centred in the right area (around a hundred-ish MHz off). As I'm testing it now, the VNA is connected much closer to the antenna (just a little below the balun), whereas before there was around two feet of coax before soldering on a connection. I was originally connecting all of the calibration standards directly to the VNA port before hooking up the feed line to the antenna. Am I correct in assuming that was going about it the wrong way, which explains the almost perfect values in the above image at my target frequency? I'm using all the same parts and the only thing different is shorter coax and cutting a new balun.
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Feb 23, 2024 08:39
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coax loss cloaks bad SWR. previously your signal was attenuated on the way to the antenna, and again on the way back. so say your coax loss is 3db. the signal loses 3db at the antenna and the reflected wave has another 3db of loss. even if you completely unhooked the antenna you'd never see more than 3:1 SWR (6db return loss). Now lets say its a looong run with 10db of loss. 20 db return loss. 1.2 SWR. this is one trick shady sellers of the G5RV multiband HF antenna use. They claim "you gotta feed it through at least 50 feet of rg8x, don't use good coax". theyre hiding the bad swr with coax loss. its just being burnt up as heat. not an actual Good Match.
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Feb 23, 2024 09:12
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Fantastic, I think now I can safely assume that the values I'm getting now are realistic numbers that I was probably dealing with from the start and now I have to put some work in to center it onto my band of interest. To be honest, I was kind of disappointed when I first hooked it up and it looked that good, I really wanted to have to use the VNA to get it tuned and learn while doing so, and now it looks like I'll have that chance. I feel like I need to be less sloppy with the balun, but the chunk of dremeled PCB I'm mounting stuff too is also pretty janky.
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Feb 23, 2024 09:50
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Jonny 290 posted:coax loss cloaks bad SWR. previously your signal was attenuated on the way to the antenna, and again on the way back. so say your coax loss is 3db. the signal loses 3db at the antenna and the reflected wave has another 3db of loss. even if you completely unhooked the antenna you'd never see more than 3:1 SWR (6db return loss). Now lets say its a looong run with 10db of loss. 20 db return loss. 1.2 SWR. Is there anything that can be done to remediate this? I managed to get an actually good mag loop(Chameleon F-Loop 3.0 Plus, a hell of a step up from the aliexpress special I was trying out before) once my annual bonus from work came in, and slapped 50 feet of coax on it so that I could maybe move it further away from the rest of my stuff. It's performing pretty well(I'll have to go back for the remote tuning motor, though), but I noticed that compared to the 12-ft coax it came with, the 50 feet line has a way flatter SWR curve, capping out at around 4:1 instead of 10:1, and with a way wider "bottom" area where it's at 1:1. Not that I'm one to complain about mysteriously "better" performance, but it seems suspect, in light of what you're saying. I'd feel better using it knowing that I'm not accidentally dumping waste heat into an expensive-rear end high voltage capacitor, or cooking off my feed line either. I love the antenna, though! I should have done this from the start. I've got the rigid aluminum ring on it, and it straight up looks like something a mad scientist would use, and can throw my lovely basement signal all the way across the Atlantic.
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Feb 23, 2024 21:19
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Better coax. The fatter the better and you want teflon. "LMR400" is the standard i use - back before the economy poo poo the bed, i picked up a 1000 foot spool of Shireen RFC400 which is basically the same as the Times Microwave stuff, ran everything i ever wanted and still have like 250 feet left over. Best $400 i ever spent on ham radio.
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Feb 24, 2024 00:43
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Here's where I'm at so far, checking to see if I'm still doing things right.  I ran across this page while looking for tips on tuning a hydrogen line dipole, and he was having similar issues with the target frequency being lower than expected for the element dimensions. Apparently he wasn't taking velocity factor into account so he cut it a bit shorter until things lined up nicely. That worked up to an extent for me, but it still wasn't looking great at 1.42 GHz. I figured maybe I also needed to take velocity factor into account for the ¼λ balun. My best guess for the RG-174/U I got out of a scrap pile was a velocity factor of 0.66, so I shortened it by that amount and got the much better values in the picture. When looking online I'm seeing people say that velocity factor shouldn't matter for a Pawsey stub but it appears to be having some effect on mine. I don't know what I'm doing! Antenna design is fun, but hard!
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Feb 26, 2024 03:57
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 Went back to a 5.3cm balun after putting it in the reflector. It's so sensitive to movement and positioning, but I think this is the best I'm going to get. That sharp drop still seems suspect to me, but it's a very short coax now so I don't know what else it could be.
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Feb 27, 2024 06:53
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Built a cubical quad yagi yesterday. should have used thinner copper wire then it would have been easier to make a rectangle out of it. i dont know the science behind it but a common mode choke 1:1 balun made swr better.   edit: ITS TAPE! edit2: drilling by hand makes it difficult to have a true straight through alignment for the wooden garden sticks. had to stick pieces of bamboo to adjust the sticks. Big Mackson fucked around with this message at 14:50 on Feb 28, 2024 |
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Feb 28, 2024 14:47
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Antennas are basically magic to me. I've never heard of a cubical quad before. Looks great! What's the use case? Or is it just for fun?
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Feb 28, 2024 15:57
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BONESAWWWWWW posted:Antennas are basically magic to me. I've never heard of a cubical quad before. Looks great! What's the use case? Or is it just for fun? its just like a yagi but teoretically it would perform a little better.  The antenna i made is for 2 meter vhf band. Tested it with winlink packet and it worked great. It is relatively easy to switch between horizontal and vertical polarization by just moving the feed point from the vertical stick to the horizontal stick. or maybe i can make some complicated dual feed setup for remote switching idk. something like that is probably invented in like 1910, like almost all other radio tech lol. edit: at higher frequencies you can buy antennas like that but it is a circle instead. here is a high weed thought. magnetic loops. array stacked. O_O Someone make the science right now!
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Feb 28, 2024 16:29
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i had a 4 element quad my dad helped me build out of pvc pipe that we stuck on a tv rotator on our chimney about 30 feet up. I could hit repeaters like 100 miles away with five watts. good poo poo
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Feb 28, 2024 18:17
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Isn't the "quad" setup something that is good for things like EME/Meteor scatter type work?
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Feb 29, 2024 03:06
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drunk mutt posted:Isn't the "quad" setup something that is good for things like EME/Meteor scatter type work? if i get a longer boom i might try 9 element quad yagi and see if it might work for such things.
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Feb 29, 2024 19:40
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Mar 6, 2024 22:45
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Okay we need a digimode now that literally sounds like farts but actually has data/text encoded in the flatulence. I suggest we call it Flatulencia.
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Mar 6, 2024 23:04
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Fahrtscriber
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Mar 6, 2024 23:05
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shTTY
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Mar 6, 2024 23:38
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THROB is a really neat sounding mode, as it actually is a volume ramp-up/ramp-down on each tone. Very eerie and what average people would consider to be "UFO noises"
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Mar 7, 2024 00:32
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hamstep: binary mode where a fast wub is 0 and a slow wub is 1
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Mar 7, 2024 07:47
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Progressive JPEG posted:hamstep: binary mode where a fast wub is 0 and a slow wub is 1 don't forget the kick + snare timing signals
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Mar 7, 2024 11:46
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new craze have hit the music market. uuuiiiuuuiiiuuuiiiiiiiiuuuuuuooooooooiiiiiiiiiuuuuuu WOW!
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Mar 8, 2024 18:33
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https://burningjustice.net/diy/wokscope/timelapse_01.mp4 Found out that it's relatively radio quiet in a friend's backyard so I set up there to collect data for 12 hours. Very happy with the results, even with the weird noise floor fluctuations going on. That spike at 1420.8 MHz seems to be an artifact from either the LNA or the SDR, but when it spikes up everything else drops. Might also be temperature related? Plenty of room for more experimentation, overall I'm pleased with imaging two areas that are redshifting and blueshifting so I can make some velocity calculations. The university is offering to reimburse me for parts because they want to make it part of their honours lab curriculum starting next year, which feels great. My lab report is going to double as a lab manual for the honours lab physics students next year, so while my statistical analysis capabilities are a bit rough I hope I can pull it together to make something decent. The actual procedure, theory, and construction stuff I have a good handle on and had a lot of fun with it so hopefully I can get my poo poo together to properly calculate my uncertainties and distributions. I already have a friend who wants me to do a guest talk at her high-school's science club so I'll also be preparing that, and when I'm collecting data in a park or other similarly radio-quiet area I get lots of interest and questions. It's like when I used to do outreach for astronomy, but because it's radio you can do it during the day which helps a lot with outreach type stuff.
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Mar 15, 2024 08:31
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Its difficult to find crossover plate with u shaped fasteners or something in norway. It looks like vertikal to horizontal antenna mounting products died when people just use internet and not yagi antennas :/ or i just dont know what kind of norwegian words we use for such things.
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Mar 21, 2024 14:50
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Big Mackson posted:
The norwegian words might be "en unnskyldning for å kjøpe en fresemaskin". In other news, I let my technician license expire 15 years ago, got it again in December, and now that I have more money than I did when I was in middle school the HF bug has bitten me hard. I just bought a study guide for my general license. Any common wisdom about doing that vs jumping straight to Extra?
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Apr 7, 2024 07:32
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Safety Dance posted:The norwegian words might be "en unnskyldning for å kjøpe en fresemaskin". You need to pass General first, but you can totally sit for both tests. Not sure if they grade your General first, before letting you take the Extra, though, I'd imagine that's how it works. The Extra test is a bit more challenging, more material (50 questions, I think), but it's entirely possible to do both in one go.
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Apr 7, 2024 15:04
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Relative to each other I'd say general isn't that much harder than tech, while extra is significantly more material/effort (but not necessarily horrible either). In my case I did tech+general in one exam visit pretty easily, followed by extra in a separate visit a couple months later. Over those couple months I was semi-regularly studying the extra exam material until the hamstudy.org test exams were consistently passing.
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Apr 7, 2024 20:44
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manero posted:You need to pass General first, but you can totally sit for both tests. Not sure if they grade your General first, before letting you take the Extra, though, I'd imagine that's how it works. They do. Any test you take they grade and then offer you to take the next level for free if you passed. You can pay for tech and sit all three in one day if you're really on your game.
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Apr 7, 2024 21:29
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Yeah I did my tech + general same sitting back to back. they offered the extra after passing the general but i hadn't studied a lick for it so i gave my regrets and walked with the general ticket.
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Apr 7, 2024 23:03
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Motronic posted:They do. Any test you take they grade and then offer you to take the next level for free if you passed. You can pay for tech and sit all three in one day if you're really on your game. Can confirm TasogareNoKagi posted:Didn't expect to take this today, but:
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Apr 8, 2024 03:38
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Congrats!
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Apr 8, 2024 03:43
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Safety Dance posted:The norwegian words might be "en unnskyldning for å kjøpe en fresemaskin". i bought a huge steelplate from biltema and someone i knew cut up several small steel plates for me. Radio amateurs accumulate a lot of metall over the years.
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Apr 8, 2024 17:05
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Just in case anyone here also does graphic design, I am currently looking for someone to design my QSL card over in SA Mart. I particularly like cards with cool typography, which is something I'd like for my own. For reference, here are a few examples off Wikipedia that I think are at least not bad: https://commons.wikimedia.org/wiki/...lande)_(45).jpg https://commons.wikimedia.org/wiki/File:QSL-F1JMM.JPG https://commons.wikimedia.org/wiki/File:Radioamateurisme_-_Carte_QSL_de_OESHL_(Autriche)_(3).jpg And here are some I do not like: https://commons.wikimedia.org/wiki/...3%A1ka_(04).jpg https://commons.wikimedia.org/wiki/File:NX1Z_QSL.jpg https://commons.wikimedia.org/wiki/File:ARSI_QSL_card.jpg https://commons.wikimedia.org/wiki/Category:Amateur_radio_QSL_cards_of_Italy#/media/File:Qsl5.jpg (admittedly, this is cool because it's clearly drawn by the OM him-/herself)
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Apr 12, 2024 11:48
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So after lurking this thread for a while, I've decided to go for my license and enrolled in a 10 week course to help study for it. I'm in Canada, and if you score above 80/100 you get what I believe is the equivalent of the American General license and can operate on HF bands. I've been thinking of getting something like an Icom-7300 once I pass, but was just wondering about the antenna situation. I live in a city on the third (top) floor of an apartment complex with a balcony which is about 25-30ft off the ground. Will I be able to get decent contacts on 20m or 40m? I was thinking of using something like this loop antenna: https://www.eham.net/reviews/view-product?id=15020 Supersonic fucked around with this message at 00:08 on Apr 13, 2024 |
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Apr 13, 2024 00:06
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i've had antenna 200 feet long and 5 feet long, and if you have an apt balcony with a railing (preferably metal) you want the mfj big stick. https://mfjenterprises.com/products/mfj-2286 it's a 17 foot whip so it's guaranteed to be good on 20 through 10 meters just by setting the length, and it's got a loading coil at the base so you can get it on 30 and even 40 meters. Also the ic-7300 is the best radio of all time, i have a yaesu ft1000mp but i use my 7300 way more
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Apr 13, 2024 05:06
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Supersonic posted:So after lurking this thread for a while, I've decided to go for my license and enrolled in a 10 week course to help study for it. I'm in Canada, and if you score above 80/100 you get what I believe is the equivalent of the American General license and can operate on HF bands. I've been thinking of getting something like an Icom-7300 once I pass, but was just wondering about the antenna situation. I live in a city on the third (top) floor of an apartment complex with a balcony which is about 25-30ft off the ground. Will I be able to get decent contacts on 20m or 40m? I was thinking of using something like this loop antenna: I recently got licensed. I just used this web page for about a week. And then used the ISED practise test page. https://www.hamstudy.com/index.html https://ised-isde.canada.ca/site/amateur-radio-operator-certificate-services/en/amateur-radio-exam-generator You might want to look at some of the cheaper and more portable radios available now. I bought a Xiegu G90. Perhaps a pole antenna on your balcony would be a good option.
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Apr 13, 2024 07:48
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Jonny 290 posted:Also the ic-7300 is the best radio of all time, i have a yaesu ft1000mp but i use my 7300 way more Hell yease.
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Apr 13, 2024 15:03
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