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welcome to 2021's ham radio, shortwave, broadcast radio, pirate radio, SDR, lorawan, CB, FRS, GMRS, and crystal radio thread this is a space to discuss radio nerd hijinks, ask how to solder an SMA connector you don't, share links of cool advances in hacker radio tech, ask questions, study for your ham license, and show pics of your dumbass radios and exploits here. I will keep the OP short-ish, but for those of you that are newer to yos, I have been playing with radio for 35 years, got my US ham license 29 years ago, and have been the top license class ("Extra") for about thirteen years now. I love radio more than any other pastime or hobby on earth, and it is my confirmed life goal to get as many people as interested in the hobby and, if they take to it, get them as set up as possible for success, fun, and liberation over the airwaves. 2021 is an interesting point to revisit this at. We have Section 230 threats everywhere, which raises the possibility of every social network dying. Really good wifi gear is available for cheap and can be hacked to work on the 2.4 and 5.8 GHz ham bands that are right next door to the consumer bands. Wanna run 1500 watts of 5.8 GHz? Budget aside, you can get the entry level US ham license and do so. But on a more serious note, a lot of people want to prepare for instability and possibly build up parallel communication networks in case the Internet turns into a lovely on-demand cable TV provider. Questions, answers, pic posts, and general rambling is welcome. I and the fellow yoshams in the cabal will do our best to guide you on your path to the magical end goal of pulling microvolt level radio waves out of the sky and turning them into rambling rants on how the new world order is deploying 5g to give everybody coronavirus. LETS GO
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Jan 2, 2021 00:27
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| # ¿ Apr 29, 2024 00:14 |
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yes yes! ok so thing 1: the rtl sdr dongles are actually not at all toys. i have one here on my desk. It is as sensitive as any radio on my bench. The place where it falls short is _filtering_. You wanna keep really strong signals that you aren't tuned to out of these, because they'll do dumb poo poo and all of a sudden you have thirty local AM broadcast stations making GBS threads up the whole shortwave spectrum. So, the RTL stick is a great start! My suggestion would be to visit http://radioreference.com (assuming you're in the US - side note, if anybody has licensing or 'what can i pick up' Q's it's very helpful to include your general nation or metro region) and see what local services have listings. Some areas you can still listen to the cops on. Some others (like denver) it's all crypto, and no, you're not cracking it. Most areas still have in-the-clear transmissions of FD, EMS and city services. http://repeaterbook.com is a good place to find out what ham radio repeaters are in your region. Setting up an RTL stick to pick up shortwave requires a bit of finesse, not because it's difficult, but because there's no gain control when it's in 'shortwave mode'. So you need to find a way to block out the AM radio stations in your area, which are 10,000 times louder than distant shortwave stations, in order to pick up the weak ones. We can get into that a bit down the road, but the VHF/UHF stuff requires a 1-3 foot antenna; a shortwave setup likes 50 feet or more of wire out your window. So, yeah, for a start, take your antenna and set it up so that it's about 18 inches long. Then put it in the window and start tuning around the VHF (technically 30-300 MHz, but we're talking about 108-174 MHz) band for any stations that radioreference or repeaterbook has listed. These days the 440-470 MHz UHF band is also pretty busy, but VHF will kick a bit farther and bend over the horizon a tiny bit. The NOAA weather stations - again, assuming you're in the US here - around 162 MHz are excellent "does this poo poo actually work?" tests. For PC I prefer SDRSharp, on a mac I use gqrx for my SDRs. Both are competent and reasonably polished programs. Make sure you google 'rtl sdr driver install' and get the right drivers in. These things were initially designed to be digital TV receivers for the Asian market, so even getting them working on conventional radio is a "hack", but it's very well established these days and most of them are designed with ham/scanner poo poo first in 2021.
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Jan 2, 2021 00:54
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i've run 150 foot runs of 14 gauge home depot THHN wire in the air before and it's plenty strong. My current preferred antenna wire is 26 gauge copper-clad steel wire from "The Wireman" https://thewireman.com/product/antenna-wire-26-awg-copper-clad-steel-stranded-jacketed/ . at RF it works just fine and it's really strong, and it's thin enough that it disappears against foliage or a gray sky. Steel wire rope itself is a fully adequate shortwave receive conductor. It's got like 10 ohms resistance along its length, versus the actual antenna impedance of a few hundred ohms. Layman's terms: you'll lose 1% of the received signal compared to running pure copper. Anyways, even lovely speaker wire will stay strung up for years. Have faith in the copper.
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Jan 2, 2021 01:07
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Here's my favorite hamtweet of 2020: https://twitter.com/KC4YLV/status/1218015470625808384 there are five diodes in the bottom right package. which is what i wanted. they were shipped in the box at top right.
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Jan 2, 2021 01:41
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i dont have any big antennas up right now, my landlord yelled so right now i only have 3 up: a 43 foot long wire, a small loop for shortwave and then a VHF antenna that i'm hiding in a tree out back
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Jan 2, 2021 20:12
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there's not a real strong lefty presence in any particular worldwide sense YET beyond DMR. there are some good hangouts on the DMR network where the chuds generally aren't present. seattle's probably a good venue to take over a dead repeater or something. if its anything like denver there are 7 clubs, each of which have 13 repeaters on hilltops, and only 3 of the whole collection ever get used in any given day once the clubs age out to literal i-cant-get-to-the-transmitter-site-in-a-hoveround levels, either things go off the air or a younger crew can step in.
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Jan 3, 2021 21:13
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don't use those DSB radios for digital stuffme posted:DSB is a cool trick but it can piss people off on the air. there was a few month period last year where people were recommending cheap DSB transceivers to run FT8 on, which is extremely rude (14.074 zero beat frequency + 1500 hz audio tone - you're now making GBS threads out inverted FT8 down on 14.072.5 and annoying Olivia folks) https://www.hfsignals.com/index.php/ubitx/ is about the cheapest i'd go. it's a real ssb radio
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Jan 3, 2021 21:38
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Zamujasa posted:I have one of those RTL SDRs with the silly cheap antenna it came with stuck to my window. It works decently well but as a second-floor apartment I wonder if I could do better. sdr sticks require a little bit of Focus because they can do so much. one weak point of them is they were basically designed as least-cost receivers for asian digital TV. Digital codecs don't care about distortion or overload because they have so much error correction, so the automatic and manual gain controls are very lacking. Ideally if you want to use one of the rtl sdr "v3" sticks (which have built in shortwave functionality) on lower frequencies, you'd put a box that is a combo antenna matcher and attenuator in front of it, because it has no gain controls down on AM/shortwave. everything is full throttle. and as a result, since AM broadcast signals are like 10000x stronger than weak shortwave ones, the former just overloads and you hear local nazi sports talk radio every 10khz. They do very well when you have a preselector or attenuator ahead of them, between the SDR and the antenna.
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Jan 7, 2021 21:57
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same idea, different values. you need much bigger capacitors and inductors down at HF for the same effect. ill post some pics of my little sdr setup this weekend
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Jan 8, 2021 04:01
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yep no question is too basic. this a safe area to ask whatever
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Jan 9, 2021 20:00
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listening is always the first key. i still recommend the rtl sdr sticks for somebody with literally zero gear. https://www.amazon.com/gp/product/B011HVUEME/ref=ox_sc_act_title_1?smid=A37V0QGFC9C912&psc=1 hamexam.org is a good practice test site. other'n that, it's most helpful to just ask - what is your environment, and what are you interested in? Some things like operating on HF ("shortwave") from a 9th floor apartment building can be difficult. An increasing number of (mostly younger) hams have taken to portable operation and will go throw a wire up in a tree in the park for the afternoon. further clarification that when i talk about 'young hams' im talking about any under 55.
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Jan 10, 2021 02:43
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When you get into SDR land, the old "sum/difference" and "harmonics" rules no longer apply. Its basically 'how does an overly strong AM broadcast signal gently caress up the ADC on a cheap SDR' Calvinball, really. But running a highpass filter that nukes everything below 1.7, 1.8 MHz cleans up any SDR stick (depending on where you are, you really don't care about anything below the 540KHz bottom of the AM band. You can tune in to some beeps for non-directional aircraft beacons, and if you're in Europe you can listen to the longwave broadcast band, but those are the sole exceptions)
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Jan 14, 2021 03:14
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oh hell yeah i use SDRSharp on windows and gqrx on mac. And i guess technically OpenWebRX for linux - though that's a web based server. (it's very cool) Follow the driver instructions carefully. there's a little hackin' to be done before it'll show up.
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Jan 23, 2021 21:03
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net work error posted:Listening to local CB radio now and no idea what's going on but I like it. basically me for the past 29 years Suspecting you aren't in the US? Is this UHF CB down in aus or something?
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Jan 23, 2021 22:09
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no thats really cool. cb is often very quiet. glad you could pick some up. 27.185 is ch19 and the most popular freq
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Jan 24, 2021 03:57
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spankmeister posted:Would still appreciate guidance on this. for HF i'm still enjoying the MLA-30+ loop. you'll need a stick or something to put it on, but it will likely do well from MW broadcast all the way up through 20, 25 MHz. bout fifty bucks USD, worth it imo.
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Jan 24, 2021 19:04
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I rambled about a couple of my late 80s / early 90s handheld radios itt https://twitter.com/jonny290/status/1353793922322100224
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Jan 25, 2021 21:28
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yeah its a regular BNC. the thing i think you're seeing is the pair of spring terminals that form the center pin socket. Still want one but i have a 703 which is one of god's own finest creations, and I don't use it enough as is. maybe when, you know, traveling is a thing again.
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Feb 1, 2021 00:26
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don't worry about the nanovna emitting RF. it's a tiny whisper compared to the old men that spend four minutes key-down on 14.200 at 1350 watts while they 'tune up the amp' and fail to ID at the end, every time
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Feb 9, 2021 19:55
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spankmeister posted:I mean I'm over here setting up GSM towers illegally and I'm not too concerned about it tbh. I would be surprised if the signal even makes it out of my living room. ho lee poo poo lmao YES
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Feb 11, 2021 21:06
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thats a really good post and in particular the "how we can hear signals below the noise floor" part is a good primer on how we do that poo poo.
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Feb 23, 2021 20:34
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nope. it was built in '99 and thats the way we like it god drat it
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Mar 12, 2021 23:38
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wonderful site. i'm fine with them doing poo poo in microwave bands (suspect that's who will end up owning our 3.5ghz band in the end), i just want them to stay the gently caress out of HF.
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Mar 28, 2021 20:10
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vodkat posted:
Yep. Some station in chicago got authorization to transmit on 14.350 MHz center frequency, but their data stream is 10khz on either side, so they're eating up the top 10khz (three voice channels) of the most popular ham band in the world and nobody is talking about it and everybody thinks this is Just Fine.
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Mar 29, 2021 20:43
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i ordered a new Weller iron, solder, solder sucker+braid, flux, some nice pliers and screwdrivers. And I got this kit in  it's a dorky little FM radio! Since we started out the zcast with an AM radio kit build, I figured this would be good to try to get motivation to get back on the horse.
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Mar 31, 2021 02:25
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yeah for sure https://www.amazon.com/gp/product/B08RXQDNL6/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1 there are a bunch of them, search for 'radio kit' for the various flavors. i like this one b/c of the red LED 7segment display and little plexi case.
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Mar 31, 2021 04:05
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these are commodity chips and are literally an fm receiver on an IC. they're super simple and rather than having to solder up finicky tuning circuits, all you're really doing is providing power and control voltages to the various pins and connecting switches. like you don't need a spectrum analyzer to peak-n-tune one of these little radios because it's as good as it's gonna get. if it powers on and squawks tunes out the speaker, you nailed it
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Mar 31, 2021 05:13
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25 year old receiver came in 100 khz-1300 mhz, am/fm/ssb/cw. good scan speed. lots of memories and search ranges. also incredibly light and runs on 4 AAs. and chirp compatible
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Apr 8, 2021 03:20
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yep. they're leaving themselves wide open. there are tons of old hams with Henry 4KL amps that they normally run at 1,499.99 watts but can easily poo poo out 3kW ---- Let's listen to beisbol chat on the new radio https://twitter.com/KC4YLV/status/1380006578640748545
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Apr 8, 2021 05:18
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https://www.youtube.com/watch?v=otS0ELOkbPk russian state news via shortwave RTTY, vintage '91.
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Apr 12, 2021 23:42
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instead of buying poo poo we built some poo poo bottom 2 sections of an old 23 foot CB antenna. I ripped out the matching network and just made it basically a straight wire all the way through. Then added a big capacitance hat made out of steel wire and a 4x4" junction box blank. You can see it if you zoom in  Here's the match box. Goal is 40 meters. I need to add some more capacitance in the box to get it down there but we're already below 2:1 SWR. Only thing I had to buy was the utility box, everything else was out of the junk/scrap pile. 1:1 balun lower left feeding the L network. Playing with a couple different tap points as you can see. Without the match box this resonates at like 10.5 MHz even though it's six feet shorter than a quarter wave would be there (the magic of capacitance hats - they're REALLY GOOD). With a tiny bit of tweaking I believe I can add a single switch to the bottom of the box and have a 40/30m setup. Initial tests late last night were very good, will try when it's really alive this sundown  schematic. Simplest matchbox one can build.
Jonny 290 fucked around with this message at 17:38 on Jun 20, 2021 |
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Jun 20, 2021 17:36
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added 440pf of capacitance in parallel with the main variable cap (remember, parallel capacitances add) and i fuckin' nailed it (also, nanoVNAs are amazing and every radio dork should get one) Picking up a couple DPDT heavy duty switches this afternoon to add 30 and 20 support. stoked!
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Jun 20, 2021 19:56
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hazza posted:Looking to get back in the RX game. I currently live halfway up a hill facing the Dee estuary in Wales, which limits my reception abilities, though I'm looking forward to trying to receive SSTV from the ISS tomorrow. Nice! MLA-30+ is a great small antenna for MW broadcast through the top end of the HF band. Love mine. --- Grabbed a couple huge DPDT switches from home depot so the tuner box has some flexibility  Left switch puts the 40 meter L network in line or not. Right switch is vestigial for now but will let me add another matching network if needed. Which i don't think i do; in bypass my rig autotuners will tune it on every band from 40 through 10 meters. It's naturally resonant dead in the middle of the 30m band so its time for me to mess with digital crap once again 
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Jun 21, 2021 02:35
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yeah, get outside if you can. ISS has like a 50 watt radio so it'll blast in full scale if you are in line of sight, but local interference can kill even that
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Jun 21, 2021 16:23
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this may be helpful for yall instructions: https://g7vrd.co.uk/public-satellite-pass-rest-api max is 72h into the future but it continually updates. i added the calendar 6 months ago or something and it still Just Works
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Jun 21, 2021 16:33
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I decided to say gently caress the  camo job on the important part (antenna) is decent. completely invis from the road. hell, almost invis from 20 feet away if you dont know what youre looking for Also switched the feed for the HF vertical from this weekend from some old lovely RG8X to a nice run of LMR400. beefy coax is beefy. Jesus those connectors are hard to solder though, just physically wrangling the cable is a pain.
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Jun 21, 2021 22:59
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it's good that you got sync yeah, a good start! I'm going to give it the college try in a couple of hours on the last pass of the day here
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Jun 22, 2021 17:52
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Oh yesterday i resoldered 4 PL-259's on the ends of some coax runs that I'd left outside and not connected to anything. I finally after thirty fuckin years learned the trick to installing them on RG8 sized coax. Drop of dish soap on the first inch of the outer jacket to help the connector screw on easier. probably the cleanest terminations i've ever done. Why did you never tell me this trick, former elmers. aaah
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Jun 22, 2021 17:54
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we'll see what my lovely tree vertical does in about an hour and change tomorrow i'll pop my very cool dual band horizontal loop and compare  sadly this is the best extant picture of it on the internet; they're out of production now and the site's gone all placeholder page
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Jun 22, 2021 18:39
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| # ¿ Apr 29, 2024 00:14 |
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Yeah now that i'm live on 40 through 10m and 2/70 i'm gonna run 1E (home, battery power) a bit and see what I can see. Time to see if this FT1000MP really is the champ of contest rigs! Ooh i should twitch it a bit maybe
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Jun 22, 2021 20:11
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