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Almost have everything I need to install my VHF/UHF base antenna, just ordered the coax and a grounding spike and waiting for delivery. I'm thinking about my future HF antenna options and like the cost and relative simplicity of wire dipoles. From what I understand with a decent tuner you can get a 1/2 wave 40m dipole to work pretty well on higher bands within reason. I was thinking of putting it on the same mast as my VHF/UHF vertical (about 21 feet from the ground) in this sort of configuration: (sorry for the awful mspaint, black is the house and mast, red is the vertical and it's feedline, blue is the proposed dipole and it's feedline. in reality the feedlines will be tied to the pole and not hanging around as in the picture)  Will I have any problems with having the two antennas and their feedlines close together? I would think not because of the very different resonant frequencies but I could be missing something. E: Also, is it better to get something like a single band 1/2 wave 40 meter and rely on a tuner to hit higher bands, or get a multiband in the same style (and still use a tuner probably) d0s fucked around with this message at 05:12 on Oct 7, 2019 |
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Oct 7, 2019 05:02
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I'm glad I found this thread! I got my tech and general class license last year. I really enjoyed learning the fundamentals of radio theory, it's actually helped me out quite a bit at work as a network engineer to know some of the concepts behind the wireless side of things when I'm setting up and deploying access points. But I've never actually done anything with my radio license. I dont honestly even know where to start. My grandfather introduced me to the hobby, and I should be getting a HF radio from him the next time I see him. But I dont know what to do in the meantime. In talking to him he jokes that cell phones do everything he used to tinker with in the hobby and now all he does is antenna designs on his property. I guess I'm interested in CW and seeing where I could make contacts but I live in a busy city and I'm sure its probably to noisey for all of that. So any advice for someone new to the hobby on what I can do reasonably easy and cheap to just get started?
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Oct 18, 2019 15:23
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BaseballPCHiker posted:I'm glad I found this thread! Sounds like you're getting the most expensive part free: the HF radio. CW and digital modes are probably your best bet, actually; I've worked people on PSK31 with a variety of random wires even when I was too "deaf" to pick up any voice communications. I've also found SSTV to be a lot of fun, in part because I can just fire up the software while I'm working and come back an hour later to see what pictures showed up. Getting an antenna is your primary concern. Are you in a house or an apartment? Apartment is doable, particularly if you're above the ground floor. My antenna setup isn't great, which basically means I can only really work people who have good antennas on their end, but luckily the hobby is full of old men spending their retirement money on antenna farms.
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Oct 18, 2019 15:56
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Pham Nuwen posted:Sounds like you're getting the most expensive part free: the HF radio. CW and digital modes are probably your best bet, actually; I've worked people on PSK31 with a variety of random wires even when I was too "deaf" to pick up any voice communications. I've also found SSTV to be a lot of fun, in part because I can just fire up the software while I'm working and come back an hour later to see what pictures showed up. Well thats good to hear! I'm not sure what type of radio it is, but I think it'll be a pretty good one. I'm the only grand kid remotely interested in this stuff and he's spent his life accumulating gear that he's all to happy to pass on now. I own my house and have several 60 foot tall oak trees on the property so I think I have some good opportunities to hang antenna wire around. I'll have to look into SSTV once I get my radio all setup.
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Oct 18, 2019 16:27
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BaseballPCHiker posted:Well thats good to hear! I'm not sure what type of radio it is, but I think it'll be a pretty good one. I'm the only grand kid remotely interested in this stuff and he's spent his life accumulating gear that he's all to happy to pass on now. That's great! If you've got two trees around 70-80 feet apart, you could put up a 40m dipole no problem. If they're closer, you should only need half the distance for a 20m dipole. Whatever you pick, put it at as high as you can comfortably get it. Due to solar conditions, HF propagation isn't super strong, but 40m is apparently working ok. As for 20m, I'm running 20m through a pretty sub-optimal antenna setup and I can still make digital, SSTV, and voice contacts. Tell your grandfather that you're interested in doing digital modes and CW. He might have an audio interface cable for the radio (needed for digimodes) and/or a spare key to give you too.
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Oct 18, 2019 17:14
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There was a crazy VHF band opening around 11PM last night, APRS packets started pouring in, had not gotten a single one with my crappy indoor mobile antenna setup for weeks previously but I was getting direct hits from all over the state last night. I heard a repeater in upstate New York from South Florida. I could hear almost every NOAA frequency when normally I can hear one clearly and another poorly. Today it's back to normal of course, but man that was nuts. e: Still trying to figure out an HF antenna solution, could somebody elmer me regarding my post at the top of the page? I got my tax return and plan on blowing most of it on an IC-178 and [some undetermined antenna]+tuner, but there's so much conflicting information about everything out there d0s fucked around with this message at 23:05 on Oct 18, 2019 |
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Oct 18, 2019 23:01
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d0s posted:e: Still trying to figure out an HF antenna solution, could somebody elmer me regarding my post at the top of the page? I got my tax return and plan on blowing most of it on an IC-178 and [some undetermined antenna]+tuner, but there's so much conflicting information about everything out there Can you do an off center fed dipole?  The most important two bands for the next couple years, imo, are 40 and 20m. This will get you on both. I've used one with good success before, and have one ready to go in a bag for portable stuff. a 40m center fed dipole is gonna suck on 20 because the impedance will be like 3200 ohms and your feedline losses will be through the roof.
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Oct 19, 2019 00:16
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Jonny 290 posted:Can you do an off center fed dipole? Yeah that would work, and yeah those are the two bands I want to start with. Do you think mounting it similarly to the diagram I drew would cause problems (using the same mast as the VHF/UHF antenna, with the balun under it)? Also, would it be best in an inverted-V or horizontal is in your image?
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Oct 19, 2019 01:37
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Nah it'll be fine. wires or metallic elements at 90-ish angles don't really interact. Horizontal is always best, but you can slope the wires like an inverted V for sure, that's how I put mine up. Just try to keep the included angle as large as possible. You don't wanna slope em down like 60 degrees or anything like that. $10 for the wire, $30 for a little 4:1 balun and then whatever coax you want to use and you're on the air. Put an eye bolt at the top of the pole and run a rope through it, that way you can raise and lower the antenna from the balun without taking the mast down.
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Oct 19, 2019 17:57
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After playing with the idea for several years, I finally took my technician exam. It only took a few hours before I showed up in the database and now I am <redacted>. I'll go back in a month or two and take my general. There were over a dozen people taking exams when I was there, and they do sessions once a month. Now I have to figure out mounting some antennas on my roof. I'm in north Seattle, so I don't have a ton of space, but my roof is pretty tall so at least I have good height. DevNull fucked around with this message at 02:21 on Sep 29, 2021 |
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Oct 22, 2019 18:33
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Sort of vestigial to actual radio poo poo, but I got the screwdriver and drill out this weekend. https://twitter.com/KC4YLV/status/1188202666821738496 (2x 285 panels, 2x 105 AH marine batteries, 30 amp MPPT controller, 50 amp AC psu/charger for when it's cloudy, 1200/2400 peak watt pure sine inverter for AC loads) the ham shack is directly wired to the battery bank via (fused of course) 4 gauge welding cable
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Oct 26, 2019 22:50
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Jonny 290 posted:Sort of vestigial to actual radio poo poo, but I got the screwdriver and drill out this weekend. Unrelated but I checked out your twitter and this blog post you linked there needs to be linked in every single ham radio publication imo
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Oct 27, 2019 20:28
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d0s posted:Unrelated but I checked out your twitter and this blog post you linked there needs to be linked in every single ham radio publication imo Yo put this in the OP of every ham thread ever.
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Oct 27, 2019 20:34
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Getting a western geostat would be pretty baller, that's true. I doubt you'll see a bunch of cranky old ragchewers suddenly see the light about their poo poo politics though, their ideas are left-behind bullshit and they'll cling to them until their grave. The two ways to fix amateur repeater culture is 1) time, or 2) a real good flu season.
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Oct 27, 2019 21:32
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Jim Silly-Balls posted:Yo put this in the OP of every ham thread ever. thirding this. mycomancy posted:Getting a western geostat would be pretty baller, that's true. 2m/70cm here is pretty much to the T what Johnny 290 is talking about. vile garbage followed with scan..scan..scan.. yea screw this *off* and on the shelf for the better part of a year. (small upside, lithium converted 727r still works like a champ, even with neglecting it for months on end) Time is on our side anyway. Family will sell their old gear for what they "paid" and we can upgrade on the cheap. As a new general class, jeezlus the prices people ask for soviet era equipment.
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Oct 27, 2019 23:21
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Imagine using technology to harness electrons to fire sound waves out of a literal magic wand across the entire planet, to have someone pick your shouting up with their magic wand only to use that technology to go “fuckin Mexicans am I right?” Sheesh. Boomers stand down.
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Oct 27, 2019 23:51
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Jonny 290 posted:My go-to portable antenna these days (which also qualifies as an apartment/limited space antenna) is the MFJ-2286 "big stick" So I ended up getting one of these and throwing it up on a tripod in the back yard, didn't even realize it was a contest weekend   It's an awesome thing for checking out what HF is all about without throwing a ton of time and money into it (and major construction projects). I haven't tried transmitting yet because my power supply only does something like 10 amps (tho it's advertised at 14) and I need to actually sit down and tune the antenna for good swr, I just threw it up and ran inside to check out what I was getting. This poo poo is really fun man e: I'm hearing stations from all over the world, ham radio delivers on it's promise e2: annd everything just went dead, just as it got dark. I thought that was the opposite of how 40 meter worked e3: oh, the contest ended at 23:59Z 
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Oct 28, 2019 00:46
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Heh thanks for the comments. I kept retyping bits and pieces of that into the weekly "durr how do we make ham radio big and popular again" threads elsewhere and wanted to put something easy linkable up.mycomancy posted:Getting a western geostat would be pretty baller, that's true. Yeah, i don't think my post is going to skew any of the olds, but you're right - they'll be gone before long. I was aiming at that 30-50 crew more, and also to the younger people that it might resonate with. d0s posted:So I ended up getting one of these and throwing it up on a tripod in the back yard, didn't even realize it was a contest weekend Yeeeeah! Good deal. glad it is working out for you, I quite like it a lot. FWIW with at least one proper 40 meter radial on it (cut a 33 foot wire), the tap for the 40m band should be about 1/3 of the way down. For 20 and higher, tap the coil at the very top so it's bypassed, then adjust the whip length. Oh, and you absolutely can transmit with that power supply - just make sure to not go above half RF power.
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Oct 28, 2019 02:33
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Here's a question that I can't seem to get answered: wtf is up with burying wires at the base of an antenna? Like, what, the theoretical and practical reasons for doing this? I cant seem to find a straight forward answer.
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Oct 28, 2019 02:51
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mycomancy posted:Here's a question that I can't seem to get answered: wtf is up with burying wires at the base of an antenna? Like, what, the theoretical and practical reasons for doing this? I cant seem to find a straight forward answer. ARRL explains it better than I could quote:At first glance, a vertical looks like little more than a metal pole jutting skyward. A single-band vertical may be exactly that! However, if you look closer you’ll find a network of wires snaking away in all directions from the base of the antenna. In many instances, the wires are buried a few inches beneath the soil. These are the vertical’s radials. They provide the essential ground connection that creates the “other half” of the antenna. Multiband verticals use several traps or similar circuits to electrically change the length of the antenna according to the frequency of the transmitted signal. (The traps are in the vertical elements, not the radials.)
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Oct 28, 2019 02:55
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mycomancy posted:Here's a question that I can't seem to get answered: wtf is up with burying wires at the base of an antenna? Like, what, the theoretical and practical reasons for doing this? I cant seem to find a straight forward answer. If you are talking about a vertical antenna they form the other half or the antenna system. Most people don't live in a salt marsh so the ground conductivity isn't the best, so the radials help deal with that. I don't think that technically you have to bury them for them to work. The practical reason to bury them is to keep people from tripping over them or getting them caught in the lawn mower (OMG don't do this, it sucks). I've also had good luck with using landscape staples to just hold the wires down under the grass in some areas.
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Oct 28, 2019 03:01
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yah they can be on the ground or shallow buried or even elevated. I had a really good 40 meter vertical antenna at our old house that was just 33 feet of wire hanging from a tall limb, the feedpoint was about 10 feet off the ground and I had 3 radial wires coming out from there. worked amazing. Right now I can't be arsed to put down a real ground plane for my big 40m, but it's bolted to the big chainlink fence around the property and seems to work fine. I may bury a half dozen radials in a semicircle just to see if it makes a difference.
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Oct 28, 2019 03:16
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Jim Silly-Balls posted:Yo put this in the OP of every ham thread ever. There are so many boomer-adjacent hobbies that need to experience that same reckoning, or they're going to die.
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Oct 28, 2019 04:28
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Young people nowadays have expensive itelephones and iairbuds and then complain about the cost of hf? Kids these days *shakes head sadly*
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Oct 28, 2019 07:36
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haha what the hell 
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Oct 29, 2019 00:48
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Metal
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Oct 29, 2019 00:53
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This isn’t technically an amateur radio question , but RF is RF and all the good RF info is here. If I have a usb NIC that can work on both 2.4 and 5ghz networks and has an SMA connector, is there any reason I can’t use an SMA Y-cable to hook both a 2.4ghz and 5ghz antenna to it simultaneously? Are there resistance/signal loss/attenuation/whatever things to worry about?
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Oct 30, 2019 00:39
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Jim Silly-Balls posted:This isn’t technically an amateur radio question , but RF is RF and all the good RF info is here. I believe you need a diplexer to do this, here's the only one I could find for those frequencies: http://www.l-com.com/bandpass-filter-rf-splitter e: this one http://www.l-com.com/bandpass-filter-rf-splitter-outdoor-diplexer-for-24-ghz-5-ghz-wireless-lan-systems 
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Oct 30, 2019 02:38
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Jim Silly-Balls posted:This isn’t technically an amateur radio question , but RF is RF and all the good RF info is here. Without a diplexer your signal will be massively distorted trying to split to two antennas like that.
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Oct 30, 2019 03:05
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they have dual band antennas that will be a good match on either band with no splitters or cables. i got some, they were like 10 bucks for a pair
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Oct 30, 2019 03:54
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What if this setup is RX only, no TX, it’s specifically only reading wireless signals. Do the same problems apply?
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Oct 30, 2019 12:37
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Yes the antenna resonance or lack thereof goes both ways, for example using an antenna tuner will also improve receive levels
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Oct 30, 2019 13:24
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OK, well for $6 I ordered the Y splitter (I actually ordered it before I posted my question, so, oops). I'll do some tests to see how it affects reception vs individual antennae for each spectrum. It will probably be bad, so I'll have to just run one antenna at a time for now. I guess it would help if I explained a bit about what I'm doing because this is a thread full of RF geeks, so maybe someone is interested in my digital Pokemon escapades. Remember Netstumbler? If not, it was this software that you could use back in the very early days of Wifi that would put your wifi card (usually a PCMCIA card, at the time) into what was called promiscuous mode, and just barf the details of every wifi network it could see onto the screen in a big list. This was handy in the early days because not all wifi cards were great at dealing with different networks, and it could be tough to see what was out there. Well, it wasnt long before people discovered that they could drive around with a laptop and gather up all the wifi networks they could see, and "wardriving" was born. In the Bad Old Days, this was an obnoxious process, even with Netstumbler. Not every card could be put into promiscuous mode, and those that could (based on the Orinoco Gold chipset) had their prices inflated quite a bit, putting them out of reach of the average hobbyist. Nowadays, every NIC can operate like the old cards used to in promiscuous mode, without any special hacks or anything. Enter Vistumbler (https://www.vistumbler.net/), a modern-day equivalent to Netstumbler. What Vistumbler does is scan once every second for every Wifi device it can see (access point or not), and report the details of it. The neat part is that it can also note where you are via GPS when it sees the network. So you can drive around, the software knows where you are, and makes a map of all the Wifi devices it can see. It can then filter them any way you wish, or, the big deal here, it can upload them to the WifiDB (https://wifidb.net/wifidb/opt/map.php), which allows everyone to see what is around them for Wifi networks.Vistumbler itself outputs its data in its own format, then into an MDB database, which you can access with MDB Viewer Plus (http://www.alexnolan.net/software/mdb_viewer_plus.htm) to slice and dice the data any way you want. IT will also spit the data out in Google Earth KML format, CSV, etc. Why would you do this? Why not? Its interesting to see whats around you, and you can see a lot of interesting data just by looking at the Wifi RF spectrum. For instance, there are multiple routes across my town where you can go the whole way on open wifi networks, OPEN WIFI NETWORKS IN TYOOL 2019. You also learn a lot about what sort of equipment is around and which businesses use what, etc. Eventuallly, as you collect enough data, you can see how and when the devices move. Its amazing how much data is out there. A one mile stretch from my house to downtown revealed 700 different wifi devices I could see from the street. This is just geocaching and pokemon mixed together, isnt it  YesWhat does it take to do this? Literally just a computer with wifi and GPS is what you need to start. My Setup -A surface 3 Pro (touchscreen and light weight is very nice in a car rig) -A generic USB GPS dongle (the surfaces inbuilt GPS doesnt use a com port, not many modern embedded GPS's do) https://www.amazon.com/GlobalSat-BU-353-S4-USB-Receiver-Black/dp/B008200LHW -A USB Wifi NIC with an SMA port for external antennas (https://www.amazon.com/gp/product/B01CCMUN8C) -External 2.4GHZ and 5GHZ omni antennas mounted on a suction mount for the car. Right now I have to run one or the other, but I'm gonna save up for that diplexer to run both. As it stands, the 2.4Ghz omni can see 5ghz signals, but I would guess not very well.  -An external 5ghz directional panel antenna for focusing on a building if needed I've been driving around at night catching 'em all and filling in my local map. The nice thing is the google earth KML maps it makes will easily let you see where you have and havent been, so you can fill more of the map in as you go.
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Oct 30, 2019 16:07
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Oh man, very cool... I miss wardriving!
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Oct 30, 2019 16:08
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My first thought was that’s a great way to establish pattern of life for a target by tracking their phone’s wifi, but maybe that’s just because of me getting into the RF nerd scene via the military.
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Oct 30, 2019 16:16
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There are for sure some creepy things you can do with the data. My personal belief is that the data is there for anyone to grab with literally any modern device including cell phones. My antenna rig allows me to “hear” the data from farther away, but that’s it. I don’t join the open networks or anything. I’m receive-only. What you do with the data is what defines its creepiness. Me? I’m filing in maps and playing Access Point Pokemon. Numbers go up and all that. The WiFiDB seems a little designed to gamify things, as it does show your overall numbers, although I’d argue the current owner hasn’t taken this far enough to get people into it. If nothing else this should help raise awareness of just what’s out there. Beve Stuscemi fucked around with this message at 16:28 on Oct 30, 2019 |
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Oct 30, 2019 16:24
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Hah, I dig it. I have my old ham mesh setup outside; a 600 mW Bullet M2 AP and a 14 dbi patch antenna at 20 feet. I should fire that up and spin it and see what I can see.
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Oct 30, 2019 18:04
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If anyone is interested in community wardriving projects, WiGLE is another project that's been around since the early '00s and is a few orders of magnitude larger. They have a really nice Android app for scanning and submitting data, though it doesn't work well on Android 9 thanks to Google throttling WiFi scan requests. Android 10 has a developer settings toggle for this so users can make it work well.
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Oct 30, 2019 19:19
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Hmmm, I do have a galaxy S5 kicking around. Can WiGLE use an external usb nic through an OTG cable?
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Oct 30, 2019 20:00
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Wardriving ah cool! You know, you should just give each antenna it's own wifi receiver. Don't gently caress around with the diplexer, it will be cheaper and easier anyways.
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Oct 30, 2019 20:57
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