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I guess i should post my mobile install work today! https://imgur.com/a/TvJ8FGK lots and lots of work, my hands are scraped up and sore, but this poo poo works like gangbusters. The hamsticks resonated nicely but they were still ~2:1 SWR because, well, that's how hamsticks work. a single one will be around 20-25 ohms. I built a quick and dirty 2:1 unun and put it between the feed wire and the SO-239, and my SWR dropped to 1.3 at resonance on 40m and 1.1 on 20. Much better. Jonny 290 fucked around with this message at 03:48 on Nov 26, 2018 |
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Nov 26, 2018 03:45
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and here we are two days later 3' mast made of copper pipe, with old hamstick ferrules pressed in, bolted and soldered, the tapped coil off my MFJ Big Stick that i use for portable, and a plain ole hamstick stinger on top. tunes 30 through 12 meters with less than 1.5:1 swr across each band without moving taps. Now to figure out how to get it down to 40m - lowest it'll go is about 9.5, 9.6 MHz with the whole coil. it's actually incredibly chill to cruise around town and listen to OMs on 20 and 40 meters, i love it. Haven't landed a contact yet but i'm still just using the IC-703 in the truck as a temporary stopgap till we figure out a real mobile rig
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Nov 27, 2018 18:55
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What is a relatively cheap and simple way to separate ethernet from computer? I am running Raspberry Pi 3 and spyserver on battery without display.
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Dec 5, 2018 08:31
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Michael Jackson posted:separate ethernet from computer What?
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Dec 5, 2018 15:16
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If you're having ethernet crap up your 10Mhz and harmonics, try a wifi dongle?
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Dec 5, 2018 15:19
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Motronic posted:What? galvanic isolator etc etc Crankit posted:If you're having ethernet crap up your 10Mhz and harmonics, try a wifi dongle? I prefer wired. tired: wifi wired: wired edit: I found out that one can use octocouplers or fiber. Big Mackson fucked around with this message at 15:23 on Dec 5, 2018 |
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Dec 5, 2018 15:20
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Michael Jackson posted:galvanic isolator etc etc So you're asking about electrically decoupling layer 1 (the physical layer)......you probably want to use multimode fiber. It's gotten surprisingly cheap. And there are SFP/SFP+ rapi hats: https://hackaday.io/project/21725-pihat-sfp-encoder. You should have much trouble finding an inexpensive switch that has SFP/SFP+es on it or a NIC with an SFP/SFP+. Motronic fucked around with this message at 16:20 on Dec 5, 2018 |
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Dec 5, 2018 16:18
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SFP Ethernet to copper boards are very cheap on AliExpress. Haven't tried them but I have some on order. Also cheap: 4G FibreChannel multimode SFPs. They should work just fine for 1gig Ethernet.
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Dec 5, 2018 18:11
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Fox 1Cliff has made it successfully to orbit and is now AO-95. It's still in safe mode for the time being.
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Dec 5, 2018 18:21
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Motronic posted:And there are SFP/SFP+ rapi hats: https://hackaday.io/project/21725-pihat-sfp-encoder. You should have much trouble finding an inexpensive switch that has SFP/SFP+es on it or a NIC with an SFP/SFP+. That is not a SFP network interface, it's just a way to connect a SFP to the Pi's I2C bus for purposes of reprogramming the EEPROM to get around the stupid limits some rear end in a top hat vendors put on their SFP support.
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Dec 5, 2018 20:15
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If it breaks out the TX Enable/Signal Detect ports you could run a UART over it!
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Dec 5, 2018 20:26
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wolrah posted:That is not a SFP network interface, it's just a way to connect a SFP to the Pi's I2C bus for purposes of reprogramming the EEPROM to get around the stupid limits some rear end in a top hat vendors put on their SFP support. Oh yeah....sorry. I could have sworn I'd seen one and I can't find it al all now. Guess it's external media converter time.
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Dec 5, 2018 21:07
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Are you getting enough RF in to disrupt it ? Shield your equipment ? That RF is in everything else if you’re blowing Ethernet link as well.
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Dec 5, 2018 23:24
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Speaking of rf interference, and I'm sure you've heard this before, so feel free to move along if your only suggestion is to buy a house on a treeless summit, but I seem to have nothing coming in to my poor little radio. The only websdr around is in Los Angeles, so I decided it was time to get out my big radio and try to find some 80m. I tried yesterday mid morning and late evening and got nothing. I've verified the connection is good; ie disconnecting the cable drops all the scratchy and the broadcast AM. I've tuned around a bit but can only raise the noise from s3 to s4 on the band, and nary a beep was heard. I tried to get 5MHz WWV as well but no dice. I tried with a long(ish) wire (okay only 6m) as well. I don't want to buy $60 of ladder line without some chance it might work. Should I just wire directly into the building ground and hope for the best? This would be for receive only. Apartments 
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Dec 6, 2018 00:29
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To give you a frame of reference, just for how much signal you should have hitting your radio, my 135 foot doublet at 30 feet off the ground has a solid S9 to S9+20 noise floor. You could be 30db or more light on signal. I of course run the attenuator 100% of the time to get the noise level back down. 75m and lower needs a _shitload_ of signal coming in to pull adequate s/n ratio out. 40 meters may be more fun. Half the wire needed.
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Dec 6, 2018 02:10
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Partycat posted:Are you getting enough RF in to disrupt it ? I havent thought about shielding my equipment. It always seemed so tinfoil your houseish. JK.
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Dec 6, 2018 10:24
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At this point I'm wondering if a full layer of tinfoil across the floor would be a better antenna. I tried something a bit more dipole last night but still nothing. I wouldn't expect to hear up to 15MHz WWV but the 5 used to make it when I was driving down the highway so I'd expect something. This is about 60ft off the ground so this is basically an antenna in free space until I get up to 10m antenna lengths; right? Can I do any better with a screw antenna vertically and some sort of grounding plane? I haven't given up yet. Not sure why.
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Dec 6, 2018 15:37
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For receive only at low frequencies the mini-whip is pretty unbeatable considering the price and size. It needs a reasonably good ground plane, a loop antenna can also work well but it depends on the type of noise sources you're dealing with. There are some very cheap loop antennas on eBay for shortwave listening that are probably worth having around. Slightly related: I modified my custom Mini-Whip design to use standard XLR connectors with phantom power a while back and subjectively it got rid of a lot of noise that I had with the old coax run. Bandwidth is kind of crappy but I "fixed" that by increasing the amplifier gain above 10 MHz by around 10 dB/octave up to ~40 MHz.
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Dec 6, 2018 15:59
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Good things in that post. Doing a bunch of reading now. Thank you!
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Dec 7, 2018 00:38
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I found out about sfp+ active optical cable so i am going for fiber media converter solution.
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Dec 13, 2018 11:57
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Michael Jackson posted:I found out about sfp+ active optical cable so i am going for fiber media converter solution. I just looked that up as I was completely unaware of them, and even after reading several manufacturer's sites touting how much better they are than twinax DACs I still can't figure out a use case for them that isn't better served with multimode SFP+es an a multimode jumper. (the only real reason to use twinax DACs is cost - and the cost of optics + cable doesn't seem much different than an active optical cable. With the optics+cable solution you have easier cable runs, the ability to use "parts you should already be stocking as spares" and choose your cable length from your box of "other parts you should be stocking as spares") Motronic fucked around with this message at 17:39 on Dec 13, 2018 |
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Dec 13, 2018 17:37
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Motronic posted:I just looked that up as I was completely unaware of them, and even after reading several manufacturer's sites touting how much better they are than twinax DACs I still can't figure out a use case for them that isn't better served with multimode SFP+es an a multimode jumper. i live on disability pension. i am not a rich person :/
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Dec 13, 2018 17:51
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Michael Jackson posted:i live on disability pension. i am not a rich person :/ sounds like fiber is exactly the network technology for you then!!! edit: oops i stepped on it again
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Dec 13, 2018 18:15
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Pham Nuwen posted:sounds like fiber is exactly the network technology for you then!!! I pay half the usual tax in December so i can afford a little more quality than dollar store itams.
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Dec 13, 2018 19:01
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Active optical cables are easier for computer janitors to deal with since you don't need to clean them. They also provide the usual benefits of higher signal quality and bandwidth.
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Dec 13, 2018 19:12
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For  Reasons  , I got my name changed legally here in WA State, via a court order, on Tuesday. I then updated my ULS and FCC information on the FCC website, with my new legal name, for my callsign. How long does it take to propagate through the system? Also - will they require a copy of the court order, or will they just accept it? Thanks!
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Dec 13, 2018 20:32
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Michael Jackson posted:i live on disability pension. i am not a rich person :/ Okay...maybe we're missing each other here. 1.) a twinax dac will not solve your problem and 2.) two SFPs and a piece of multimode costs the same or less than this things you found. Because that's what it is, just with the fiber permanently connected. The rest of the content was commentary on how, as someone who does datacenter buildouts for a living, I don't understand the application/advantage for those things.
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Dec 13, 2018 20:57
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Motronic posted:The rest of the content was commentary on how, as someone who does datacenter buildouts for a living, I don't understand the application/advantage for those things. I do have a case where AOCs could make sense: A product I've worked on is supplied as a full height rack with several servers and some 10 GBit routers at the top, there are 10+ 2-3m single mode fiber runs going to the servers. AOCs would make some sense there since the rack has a fixed set of components and I/O, and they cost less than the current single mode solution. Cleaning also isn't an issue (and the rack is installed in remote customer sites with limited maintenance so fixing stuff is expensive). DACs aren't an option there since the equipment isn't certified for them.
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Dec 14, 2018 08:39
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Howdy, folks! Long-time listener, first-time caller. One-shot my tech and general tests and got my callsign the same day. Keep your eyes and ears open for KN4REK!
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Dec 14, 2018 18:07
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congrats, and my obligatory THEYRE ON KN4 NOW? (i'm a kc4) ham stuff is fun and i do it every day That's a good callsign!
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Dec 14, 2018 18:50
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Motronic posted:Okay...maybe we're missing each other here. Same or less? Then i will use two sfps and multimode solution, since i can have custom length.
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Dec 14, 2018 19:46
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How would a totally ignorant noob go from zero to mucking around on HAM radio? After reading Seveneves (sci-fi novel where a character communicates with her family using radio) I'm curious about how it works. I am a Canada-goon.
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Dec 14, 2018 20:53
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Pixelante posted:How would a totally ignorant noob go from zero to mucking around on HAM radio? After reading Seveneves (sci-fi novel where a character communicates with her family using radio) I'm curious about how it works. I am a Canada-goon. If "mucking around" means actually communicating with anyone or otherwise transmitting, you need a license first in pretty much every country. Are you looking for technical info about how radio communication occurs, procedural info on how radios are used, regulatory info for Canada, some way to just listen and see what's on the airwaves, or something else?
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Dec 14, 2018 22:44
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longview posted:they cost less than the current single mode solution. Multimode costs less than single mode - who woulda thunk? Is also uses less power. I was comparing these to 2 multimode optics and a piece of multimode patch cable.
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Dec 14, 2018 23:49
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poeticoddity posted:If "mucking around" means actually communicating with anyone or otherwise transmitting, you need a license first in pretty much every country. Hopefully communicating, but I'm really ignorant about how these things work. I'll take any advice on a) how they work, b) how to use it myself, and c) how fussy the licensing stuff is. Any good guide book recommendations?
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Dec 15, 2018 01:40
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Pixelante posted:Hopefully communicating, but I'm really ignorant about how these things work. I'll take any advice on a) how they work, b) how to use it myself, and c) how fussy the licensing stuff is. Any good guide book recommendations? This was the first overview of amateur radio I could find on YouTube that was under 5 minutes (if you skip the VPN promo at the end) and was produced by someone whose entire channel wasn't focused on amateur radio. https://wp.rac.ca/ This looks like the Canadian analog to the American Radio Relay League (AARL), which is an organization that heads up most lobbying related efforts in the US and also produces some of the most commonly used study/learning materials for amateur radio licensing. I don't know if RAC produces any study materials, but they've got a staff of 2, so I'd imagine they're just fine getting directly e-mailed about recommended guide books and whatnot. I'd recommend the ARRL books, personally, but they're meant to prep you for the American licensing process, so they're going to have a lot of info that's not useful for you (though the theory, etiquette, etc. would be universally useful). https://www.ic.gc.ca/eic/site/025.nsf/eng/h_00006.html This appears to be a FAQ about amateur radio licensing in Canada, but I know very little about Canadian amateur radio laws so there may be somewhere else where the technical details are stored. The general idea with amateur radio is that governments recognized pretty quickly that it might be a good idea to have a bunch of people (instead of just occupational specialists) who knew how to send and receive messages via radio during emergencies, so they allocate some portions of the electromagnetic spectrum for licensed amateur (i.e. not-done-for-profit) use with some caveats. While most radio stations, radios used for business use, non-licensed radio systems (like garage door openers), etc. are restricted to a single frequency or a list of pre-approved frequencies, amateur radio communications occur within a band. There are restrictions on some sub-sections of bands (regarding what method of communication is allowed) but within a band a licensed amateur can tune to any open frequency and start transmitting (which is different than broadcasting, because communication is bi-directional). This is mostly done for casual communication, but is well suited to emergency use, and sometimes there are formal contests and other events. There's a lot of regulations (hence there being license study materials) but the things worth knowing up-front are that amateur radio activity cannot be encrypted or otherwise used in a fashion that prevents regulatory agencies from monitoring it, it cannot be performed for profit, and transmitted messages cannot be obscene. If I was going to recommend a starting point to someone who's completely new, I'd say check out this site: http://websdr.org/. You can poke around in different places across the world and listen to everything from amateur radio communications to aviation traffic to broadcast music. It really gave me a sense for just how big the spectrum is and how much radio communication goes on. Plus, it'll reinforce patience and learning to listen through noise, which are good skills to have. I probably spent two or three weekends just poking around on there before I finally broke down and bought a cheap radio and some study books.
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Dec 15, 2018 02:39
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https://hamstudy.org is a good site for studying the exams, and they also have the Canadian Basic and Advanced exams if you go into "Other..." According to this page you would first obtain the Basic licence and then you could upgrade to Advanced later if you want. It looks like the only real benefit to doing so is being able to increase the power that you're transmitting at. Note that the licence would only be required to transmit. If you're interested in just seeing what's out there, you could also put together a receive-only setup for fairly cheap. The ingredients would be: - An SDR dongle that accepts an antenna connection and connects to your computer over USB. This would be "the radio". I have an Airspy HF+ which I really like, but you can also get ones like an RTL-SDR for around US$20-30. - A computer to plug the SDR dongle into, running software to receive the radio data over USB. I use SDR# ("SDR sharp") but there are a few good options for this. - An antenna. This part is a very involved part of ham radio. There are all kinds of options for what antenna you'd get, and there aren't really any right answers as the correct antenna depends on the frequency you're listening to. In practice the biggest single factor is where the antenna is located; if you can get it to the top of a hill or over your roof line then you're much better off than in a valley or indoors. Also, when it comes to antennas cheap can often be better. Just throwing a scrap wire up into a tree can capture as much if not more signal as a $500 vertical on a mast. The above RTL-SDR.com site has an SDR+antenna kit for US$28, so you could just buy one of those to start with. You may have better results if you do this on a laptop that you've taken outside, as indoors you will likely find all the RF noise sources in your home.
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Dec 15, 2018 04:09
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Super helpful, folks!
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Dec 15, 2018 04:42
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poeticoddity posted:This was the first overview of amateur radio I could find on YouTube that was under 5 minutes (if you skip the VPN promo at the end) and was produced by someone whose entire channel wasn't focused on amateur radio. RAC is the Canadian equivalent to the ARRL; there’s their how to start link at the top of their page. They also have lists of the radio groups for each area, if you want to go meet greybeards in person. They do have study books for sale on their site, which are Canada specific. Basic and advanced qualifications can access the same spectrum, advanced has increased allowed transmission power, the ability to run remote equipment, and the ability to build your own radio. The Industry Canada website has the actual exam generators on the site in the menu on the left, and has the list of accredited examiners that you can go to for your exams. You’ll deal with IC for licensing, etc - they regulate ham radio in Canada. Look at the RICs and the RBRs for regulatory information.
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Dec 15, 2018 18:15
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The FCC has rejected my name change, because they probably want a copy of the court document. Yet, there's no place to upload a scan of said court document. 
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Dec 15, 2018 22:14
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