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Woof Blitzer posted:I am studying for Tech. I don't want to use this crappy baofeng anymore! What HT and antenna combo will let me hit digipeaters/sats from a good distance? Sup tech-studying buddy. I found this while researching satellite-specific rigs: https://static.dxengineering.com/pdf/intro_to_ham_radio_satellties-sean%20kutzko_kx9x.pdf Can any experienced folks in the thread comment on his gear? The mobile rig seems pricey but versatile.
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Jun 24, 2021 09:08
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| # ? May 12, 2024 20:13 |
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Feeling p good this morning after this: https://twitter.com/richardgarriott/status/1407975342254575617?s=21
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Jun 24, 2021 09:44
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I got one of his dad but it was slanted as I missed the very start of the preamble and so I need to fix the image *post saving from MMSSTV* Any ideas? I have a possible python script idea to shift pixels maybe?
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Jun 24, 2021 12:08
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Woof Blitzer posted:I am studying for Tech. I don't want to use this crappy baofeng anymore! What HT and antenna combo will let me hit digipeaters/sats from a good distance? For Digipeters, I assume you mean APRS digipeaters? For that you're pretty much going to be using either an APRS-enabled radio (which can be a pretty penny), or hooking up something like a mobilinkd to your phone and HT and using ARPS.fi/APRSDroid.
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Jun 24, 2021 13:24
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Wow, I was like Richard Garriott from Ultima? I guess there's also an astronaut named that (googles) well, poo poo, what am I doing with my life that I didn't create one of the most iconic video games of the 1980s, visit the North and South Pole, the bottom of the Marianas Trench, and install an SSTV system in the ISS during my vacation there?
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Jun 24, 2021 13:34
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Huh, poo poo. Today I learned that Lord British's dad flew on Skylab. Had no idea his space tourism thing was in a sense continuing the family legacy.
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Jun 25, 2021 19:50
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Woof Blitzer posted:I am studying for Tech. I don't want to use this crappy baofeng anymore! What HT and antenna combo will let me hit digipeaters/sats from a good distance? Does it need to be an HT? A better antenna can help an HT hit the satellites and repeaters. Otherwise a mobile radio with like 20 or 50 watts might be helpful. If it doesn't have built-in APRS (some do) - you can pair it with with APRSdroid on an Android phone/tablet or a regular laptop with e.g. Xastir to send and receive APRS by letting the phone/tablet/laptop work as a sound modem and scream APRS packet through the radio. APRSdroid can even send APRS packets via Bluetooth or even Wifi/4G if you don't have a radio. Vir fucked around with this message at 02:18 on Jun 27, 2021 |
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Jun 27, 2021 02:16
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the thing about satellite work is that it's only really responsible to do it with a full duplex radio - or two radios - because you need to hear if you're stepping on somebody. Yes, you can get qsos with a regular dual bander but you run the risk of being unintentionally rude. Not trying to come down on you on that, just be aware that for many hams a 'satellite ready HT' means full duplex which tends to thin your wallet quickly.
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Jun 27, 2021 02:57
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Or use two radios, one to listen and one to send. One benefit of duplex is to hear yourself if you're making it into the satellite and if you're on frequency.
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Jun 27, 2021 04:29
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Yeah, two rigs is totally fine. The apocryphal FT-1634 is the biggest example.
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Jun 27, 2021 05:07
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One option for really simple satellite work is the Kenwood TH-D72, although you might have to get it used because I think the discontinued it. https://www.kenwood.com/usa/com/amateur/th-d72a/ I picked one up for satellite work because it does full duplex and does APRS, which enabled me to hit the ISS repeater and get a QSL card.
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Jun 27, 2021 05:37
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A frustrating few days of failed ISS SSTV captures (plagued by pager intermod right on 145.800 from out of band that I didn’t have for the MAI event at the start often month) over the last few days, missing the start of frames and having poor slant issues that I couldn’t fix post-Rx left me amazingly sad. So I did my first ever NOAA capture instead from 15: A bit of an alignment issue (edit: you can move the map!) so we’ll see how it goes next time. This was with the Slim Jim so perhaps not the best antenna. I have a dipole I can set up in a V to try again. Why did that intermod for the SSTV only now become an issue? It was better with a telescopic on the HT, lay on the floor, frankly. Eventually the capture effect takes over and it’s fine but for those low elevation passes it’s killing my frames. thehustler fucked around with this message at 16:12 on Jun 27, 2021 |
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Jun 27, 2021 15:05
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best I could do this time: mad at myself as i should have adjusted the carrier down to account for the redshift that was clearly visible in the sdr waterfall and i could have gotten more of the frame; oh well, it was certainly fun trying
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Jun 27, 2021 17:41
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Here's my SSTV image captured on a Yaesu FT-60 with the stock antenna, audio played aloud into Audacity, then played back over speakers into the iOS SSTV app. I am super happy with the results yet at the same time, as my radio pal put it, "the challenge is manifest". Can't wait for my next chance to get a crisp image using better gear (and logistics).
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Jun 29, 2021 07:44
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Not bad! an actual cable should bring that up into pretty clean territory on the audio side.
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Jun 29, 2021 18:11
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In unrelated news, uh, just wanted to share the latest from MFJ's mailing list. Great time to go full Culture War, Martin.
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Jun 29, 2021 19:15
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well what ARE the mfj products that are plain looney? coldjoint mcarc?
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Jun 29, 2021 21:16
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Sniep posted:well what ARE the mfj products that are plain looney? Seems the message was toned down on the web site: https://mailchi.mp/67ff28081dd0/pep-le-pew
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Jun 29, 2021 21:19
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Well, being "canceled" over some BS reason does count as a marketing tactic I guess. If someone on Twitter digs up that you donated  to Candidate A in the previous election, that is a sure-fire way to get your game trending in Steam sales. But I doubt Warner Brothers is going to like their characters being used to sell commercial products that they haven't endorsed.In other Elmer Fudd news, I'm now "elmering" a new ham, and that is fun.
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Jun 30, 2021 15:09
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Vir posted:In other Elmer Fudd news, I'm now "elmering" a new ham, and that is fun. I certainly hope you're using the accent.
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Jun 30, 2021 15:12
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Just got my monthly hosting bill for Vail: Turns out running a repeater for one of the lowest bandwidth communication media ever devised is pretty cheap.
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Jul 1, 2021 21:09
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Made my first ever NOAA composite this morning. It’s loving sweet. I’m so addicted. Will a QFH antenna help with noise on the low angle passes? 
thehustler fucked around with this message at 12:09 on Jul 3, 2021 |
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Jul 3, 2021 12:06
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that's really good quality! QFH antennas will have a good circularly polarized pattern at low angles which helps tons with fading.
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Jul 3, 2021 17:43
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Jonny 290 posted:that's really good quality! Will that gently caress up the high angle parts of the pass or is it too high a signal to really care at that point?
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Jul 3, 2021 18:57
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Yeah you dont give a poo poo about zenith or whatever. those signals are easy to get barring a deep null overhead. --- Built a 4:1 current balun today. two ft240-43 cores, 14 gauge THHN, cut zero corners. this thing could take like 2-3kW continuously and i'd still trust it.  So far it works fuckin' great. it's being used on my off center dipole (22 ft one leg, 44 the other). Nice SWR dips at 40, 20 and 10m.
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Jul 3, 2021 22:22
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Back to doing some RF projects, gonna try to put together a fiber coupled remote transmit system for VHF/UHF. Idea is to couple the transmit power from the radios inside into a laser (through a solid attenuator), then run that out to an optical detector in an outdoor box. Then I'll use a diplexer to route the appropriate band (2m/70cm) to its PA. The PAs will have a carrier squelch to determine when to transmit. I already have suitable active receivers to hook up to the radios, so this specific system can be transmit-only which is nice. Just put together a functional prototype for a 70cm PA (since I had the hybrids laying around):  The VHF version will likely be almost identical aside from using a VHF rated hybrid. The chassis is an old GSM-R transmitter, I pulled the PCB, hot-air removed all the components from it, then put it back upside down. That way I have a nice form-fitting PCB with a solid ground plane to work on. The Dremel diamond cut-off wheel is ridiculously good at cutting PCBs by the way (E: I should note this is a 0.8 mm RF PCB, not a standard FR-4 type). The input power is sampled and detected in an AD8307 RMS detector, which then runs to a comparator. When the power level is above ~-10 dBm at the input the first stage power to the PA is turned on. There's a VNA-25 preamp which has adequate output power to drive the hybrid up to full power with around 1-2 mW input power. After that there's a basic PIN diode attenuator which is used for power control. At the output there's a 5th order low pass filter set to ~500 MHz, and an attempt at a directional coupler going into another AD8307 (not sure how directional it is, but the signal at least corresponds to power). This measurement is used to regulate the maximum power level to around 10 W (adjustable, the module can do ~30 W peak). A regulator controls the input PIN diode to attenuate the input signal if required. I later covered this coupler stage with copper tape to shield it, and to avoid the coupling amount being affected by the lid. Not sure if I should also cut off the output stage power supply when squelched, I don't really want this thing sitting around generating output noise (there's no output relay, yet at least). I'll probably do a test at some point where I just power up the PA connected to an antenna and see if this affects the receiver system noise floor. If it does it's fairly simple to modify the system for full shutdown by adding another power switch transistor. It remains to be seen how well this will work for DMR, I may have to adjust the receiver AGC system to respond very quickly to avoid issues with repeater access. I may also have to tune the power regulator bandwidth a bit in the PA as well, to ensure it doesn't mess up the time/power envelope specification for DMR. longview fucked around with this message at 15:03 on Jul 5, 2021 |
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Jul 5, 2021 12:40
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Just use an optocoupler maybe? I don't know why you would want to deal with fiber.
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Jul 5, 2021 20:47
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Did anyone listen to the transmission of SAQ Radio Grimeton on 17,2kHz VLF? For those who are not aware, SAQ Grimeton is the only surviving alternator transmitter in existence, and is still operational with its ~6km long antenna. It was built in the 20s for transatlantic telegraphy with the USA, but very quickly surpassed by shortwave station. However, it was used until the 1960s for communication with submerged submarines, and AFAIK the Swedish navy rented it until the late 80s. Until the 60s there were two identical Alexanderson alternators in the building, but one of them was demolished and replaced by other equipment. Presumably shortwave but considering the Navy used the station until the 80s, possibly also more modern VLF equipment. The transmitter makes its 'RF' energy with a huge, very special high frequency alternator. Here's a video of the tune up procedure: https://www.youtube.com/watch?v=zX-T48jwQOM&t=60s I've been struggling with receiving them because of a high amount of local noise, sadly. But i've picked them up with a simple preamp connected to my sound card a while ago. I can receive the french and norwegian submarine communication systems with ease, though. Especially the french one is so strong, that it gets right through my decently shielded input cables, without a signal source attached. I've experimented a bit to see if a VLF allocation would be interesting for amateurs - my record with a 75*75cm loop antenna and 5w of power, is 60m thus far. I guess it would only be useful as city-wide communication at best, unless you like QRSS digimodes. LimaBiker fucked around with this message at 21:13 on Jul 5, 2021 |
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Jul 5, 2021 21:07
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SEKCobra posted:Just use an optocoupler maybe? I don't know why you would want to deal with fiber. this is longview's long term project. the idea is to use only glass between shack and the 'tower'. he wants to transmit actual watts of power over glass and turn that into Radio Waves. it's pretty bleeding edge tbqh (fiber feeds to pole/tower mount radios would be a quantum leap forward as far as lightning safety goes)
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Jul 5, 2021 21:20
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Sorry, life scientist here, so much of the physics behind radio and RF is new to me. Wouldn't it make more sense to send a weak information signal via fiber to a converter/amp at the base of your station, and have that converter/amp combo turn the photonic signal into electricity then amplifying it for broadcast? Wouldn't that get you all the protection from lightning, totally eliminate RF noise, and be much easier than blasting 100 or 1000 W of light through fiber? I may be missing something here...
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Jul 5, 2021 22:38
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Just finished very carefully taping up a bunch of fiber into a tiny hammond box while watching the power readings to avoid excessive bending. Now I have an active optical receiver box with quite decent shielding, it can output ~10 mW electrical which is sufficient to drive the 70cm PA I built earlier today with a decent allowance for diplexer losses. I also added a thermal cutoff switch to the PA to prevent it melting in summers - seems like it either won't fully overheat, or will only extremely slowly overheat sitting in a room with no external airflow. Does get too hot to touch after ~5 minutes at 10 W though, but seemed to stabilize around 60 degrees case temperature. mycomancy posted:Sorry, life scientist here, so much of the physics behind radio and RF is new to me. I already have a few active receivers that put the laser diode right up in the antenna to get essentially noise-free/"lossless" transmission without any electrical connection, so this is an extension to that system. I described the HF over Fiber concept a while back in this thread, I've since also built a VHF wide-band receiver using the same concept and chassis, and I have a 70cm + L-Band (GPS + other stuff) dirty prototype running now. Obviously you could argue that I should just get an networked radio and run that over fiber, I've decided to draw the line where it's most fun/not stupidly expensive/not ridiculously complex to implement. This system is fairly flexible wrt. what radios are hooked up (I like to change radios around), and is feasible to build in a fairly short time mostly using stuff I already have. Jonny 290 posted:actual watts of power over glass I actually pulled all my external coax lines over the weekend and now I only have a through-door 8-core fiber run for I/O, so if I want to transmit I'd better get this thing done! LimaBiker posted:Did anyone listen to the transmission of SAQ Radio Grimeton on 17,2kHz VLF?
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Jul 5, 2021 23:35
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Thanks for elaborating, it sounds like a really cool project!
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Jul 5, 2021 23:46
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Well poo poo, I just had to turn on DC blocking and… I have a Meteor image! Amazing detail and I got to compare a distinctive area with the same area on a NOAA pass 10 mins later: https://twitter.com/markpentler/status/1412195053347524613?s=21 Pretty cool
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Jul 6, 2021 00:49
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have a shack pic feelin it these days (the monitors are 100% visible when you're in the chair, i had to step back to get it all)
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Jul 6, 2021 05:05
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 im in my HAMmock
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Jul 6, 2021 18:26
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Anybody in the SF Bay Area have a CHIRP file for local repeaters? I hate typing all that poo poo in by hand, plus it's hard to tell what's an active repeater vs. just somebody's vanity poo poo that never gets used. I finally dug out my IC-W32A after the move.
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Jul 6, 2021 18:34
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HE LIVES! I'll ping a work hambuddy out there and see what's what
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Jul 6, 2021 18:42
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One weird trick to making your RF power control more accurate: cover the power detector IC in copper tape. I was getting up to 2x changes in amplitude when removing the cover (going up with the cover off), seems there was some resonance inside the chassis causing additional coupling into the power detector. Ran it at 10 W, after around 1 hour it had started thermal cycling on/off, with the chassis at around 70 degrees - I set up 2 degrees of hysteresis so it cycled in around 1-2 minutes. I actually did this test through the optical link (using an off the shelf laser transmitter) and the amplified PIN detector (2xPSA4-5403s in series), no issues found so far! Here's the PIN receiver (I later added a second MMIC amp to get a more suitable output level). The coaxes are 1.13 mm microcoax (the type used for wifi antennas etc.), it costs almost nothing on AliExpress and is super convenient to use for solder-down applications. The dielectric is not fully solder-heat resistant but it does survive pretty well. The SMA on the side is a U.FL/SMA adapter cable where I just cut off the end, super convenient and quite cheap. U.FL connectors are also good for test points on proper PCBs.  Put in some M4 rivnuts in the base for mounting it later, it will probably mount to some kind of bracket. The actual circuit is simply the PIN diode cathode to +5 V, anode DC grounded through an inductor, and the anode AC coupled to the MMIC input. This is a common way of hooking up photodiodes for high frequency operation, the reverse bias reduces the diode capacitance slightly, improving bandwidth (not by a huge amount though).  I decided to YOLO-mount the PCB and the 7805 (in the top half) using countersunk steel pop rivets, drat solid but a massive pain to remove. Note that you can get Dymo D1 labels in black on transparent with the good glue (durable type), I had to mail-order it but it looks so much nicer than the standard types. Also worth mentioning that 3M 69 tape is a very funny name for a tape, but it's actually pretty useful, it's a heat resistant silicon glue glass-fiber tape suitable for mechanical reinforcement, for example where cables might rub. I used some to reinforce the fiber feedthrough, wrapping some around it near the entry point then soaking it in superglue to stiffen it. The fiber runs through a 2 mm hole in the side, which is small enough that standard cellular signals can't penetrate it, this will be important since I'm putting this whole thing in a plastic bud-box and putting directly in the main beam of multiple 4/5G towers.
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Jul 6, 2021 19:44
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Casual Encountess posted:
King of the 'fengs over here.
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Jul 6, 2021 20:02
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| # ? May 12, 2024 20:13 |
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I reassembled my homebrew buddipole I built back in 2012 and used it for a bit this past weekend while my wire antenna is down for some house repairs. At 16' it was basically NVIS for 20m, but I did manage to work K2M and K2D on CW, so I guess it works! The pole can extend up to 24', so maybe next time I will try a bit higher.... but my 30' fiberglass mast and an end-fed wire is way easier to deploy and probably way more efficient. 
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Jul 7, 2021 01:07
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