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Somehow those simple pixie kits are harder than i expected to get working well. I built a pixie on some copper clad board which worked just fine, but i managed to destroy 2 of those kits. Turns out, running the 9v kit on 12v blows up the final transistor, a diode and a choke. I'd say 'just plop in any random transistor and see if it works'. Perhaps check out the original pixie design for some bias resistor values. Also, hi, i'm LimaBiker, QTH Amsterdam, and i like to fool around with radio stuff that is two or three times older than i am. If anyone needs advice on how to fix tube equipment, let me know.
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Dec 16, 2020 01:56
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Big Mackson posted:That radio amateur probably wonders why there is so few joining the hobby nowadays. There are some amateurs that are very... go big or go home, kiddo. Yep. There is a whole lot of looking down to people who don't have a several hundred or thousand euro transceiver. gently caress them. I fixed my own lovely Wireless Set 19 and heard my signal more than a thousand km away on Moscow's webSDR. WS19s are legendarily lovely but it worked, and that's the most important bit. I replaced it with a GRC-9 which is so much better. Don't have an antenna at the moment, sadly. Both of those radio's i got for free, which was nice cause for a long time i couldn't afford to spend much money on radio equipment.
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Dec 28, 2020 01:01
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at someone calling out people on air not saying their name but says enough info that they KNOW the one being called out hears them.
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Are there any west-european hams here? I'd like to try to make some contacts with people i already somewhat know, or at least people who i can message with. I have a bit of microphone anxiety... Currently my range is somewhat limited. I can reach the UK and Germany on 80m in the evening (if i string up my antenna again). I also wanna improve my morse. If anyone wants to practice with me - i can send decently at 12-15wpm, but my receiving is kinda meh at around 10wpm. People on the bands are not always interested in more than a quick standard qso and that makes learning to receive properly a bit hard. Practicing off the air is fine too  if you live too far away.
LimaBiker fucked around with this message at 23:33 on Dec 29, 2020 |
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Dec 29, 2020 23:28
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Hey folks! I am in a bit of a lovely antenna situation. My 'Antenna tree' was sick and is cut down. That was at 18m distance from my bedroom/shack window, which worked very well on 40 and 80m. Now i'm really trying to get back on air on 80, and preferably also on 160. However, i only have trees at ca. 5m from the window, and ca. 8m from the window. First thing i tried was stringing up a wire to the tree 8m away. This barely worked. Never heard myself any further away than 300km, with 25w of input power on 40 or 80m. Now i'm thinking about stringing a wire between the trees. The distance between those is something between 10 and 15m. But i'm doubting what exactly i'm gonna do. I can do either a horizontal L-antenna, or turn it into a dipole. The most important band for me is 80m, and eventually also 160m. I realize that this is way too long of a wavelength for efficient use - but that doesn't bother me. My main goal is to get *anything* in the air on these bands. So, do horizontal L-antennas work? I highly doubt that a dipole this short (relative to the 80m/160m wavelenght) does anything at all.
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Jan 10, 2021 22:26
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All wire will be pretty much at the same vertical level. Can't really go very vertical. Everything of the L will be horizontal, or at best a meter higher than the feed point. The total length of wire will be 15 to 20m. I already have a tuner that can tune just about anything. My GRC-9 has a built in tuner, for my ft-101 i use a diy external thing (that i gotta upgrade cause at 20w things start to get a bit sparky...) 160m is a bit of a stretch, yeah. But anything is better than nothing, and (if i get the 160m band on my yaesu ft-101 working) i have over 100w of cw or psk31 power at my disposal. Next question: my FT-101 works very well on 80 to 15m. But on 160m, output power is just 25 watts at best, and the cathode current very high. Does anyone recognize this kind of problem? It does transmit on the correct frequency when i tune it to let's say 1850khz, but the cathode current is ridiculous - with the same current on 80m, it would put out something like 100w. Tested in a dummy load, of course.
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Jan 10, 2021 23:09
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Jonny 290 posted:(sorry for linking to The Bad Place but, you know) Heh. I changed my avatar to some equal rights icon that went around the world a few years ago. Don't recall exactly why, but pretty much in response to a whole bunch of posts like "it's discussible that LGBTQ+ people should have rights'. I haven't been there in a long time (well, i just posted the same question there). I am now a bit lost. It seems to not go above 40w carrier power anywhere now on tune or CW. On CW it should put out 90w, right?! I'm tempted to open up my dummyload and measure voltage directly on the resistor with my scope and calculate power, because i am starting to worry if my swr/pwr meters are displaying power correctly... Dummyload does get nice and toasty, but that's a little 50w CB quality thingie not rated for continuous use. I don't remember if i've ever seen 90w on my own meters - i did get the thing to another guy who did see that it put out in the area of 100w on 80m. Bear with me while i figure out if the meters are reliable, before everyone starts to put in effort for something that's just a lovely meter. E: Connected scope over dummy resistor with 1:10 probe. TX set to CW. Full power tests for *very* short periods. Tuned to max output (first dipped, then tuned to max output according to manual) 21.100 - 75v = 56w = meh 21.250 - idem. 13.9 - 80v 14.000 - 80v = 64w = meh 14.1 - idem 14.2 idem 7025khz full power = 100v (p) over 50 ohm = 100w, great. I(c) 320mA 7100 = 90v 7200 = 90v 3525khz full power = 110v (p) over 50 ohm = over 100w, correct. I(c) max 325mA on built in meter. 3800 - 100v, totally fine. 3900 - 90v, fine. Below 1750 - not tunable, preselect doesn't go low enough. 1750 - 65v = 42w = too low. I(c) 220mA. 1800khz - 60v = 36w. Way too low. I(c) 200mA. 1850 - idem. 1900 - 60v, I(c) 180mA. LimaBiker fucked around with this message at 13:30 on Jan 11, 2021 |
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Jan 11, 2021 12:38
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Motronic posted:Yeah, you're way low. I was peaking above 120W on 20 and 80 at least from what i remember from the last time I used it. I haven't checked peak power on SSB. Undoubtedly that's higher. But 90w is the rated power for CW, so i think it's fine on 40 and 80, too low on the rest. Re: X-Phase noise canceling - i've heard good things about them. I'm planning on making one myself.
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Jan 11, 2021 18:25
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Update on the FT-101 issues! I got some useful advice on the qrz forums. The 160m band now gives a whopping 140w of power, which is more than okay for this radio. 80 and 40m were already fine. 20 and 15 are weak, with just 65w of power. And 10 is still glitchy. Weird things going on there. What i did was first check the neutralisation again - the guy who i first went to for advice, apparently did it wrong. Odd, he's a knowledgable guy. Oh well, everyone makes mistakes. Then: peak RF frontend for max signal strength of the internal calibrator, het osc trimmers for maximum TX power, and then grid and plate of the driver for max TX power. Somehow, for 20m and upwards this was not enough. I got a 10-15w increase after doing that, but 65w... not enough. Well, it's enough for what i wanna do, but it should be able to do more.
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Jan 14, 2021 21:30
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Ambrose Burnside posted:I'd like to be able to pick up 40m etc band amateur frequencies on SDR and ideally be able to do QRP stuff on the same frequencies down the line (I actually built a Pixie but haven't done anything with it b/c no antenna); beyond that it'd be nice to have a better general-purpose antenna for SDR noodling-about. Loops are nice, compact, and a godsend in high QRM areas. In my place, i have always had better reception results with the loop than with any other antenna. But they have big limitations. Firstly, you gotta tune them every 10-25khz or so. This means that you either have to set it up near your RX location, or build a remote control for it. Secondly, they are not as efficient (in transmitting - they are perfectly fine for receiving) as something like a dipole or a quarter wave monopole. For reception, any old wire will do. For QRP transmitting, make it out of copper brake line or out of thick coaxial cable. An old broadcast air variable tuning cap will do for the voltages you'll find at QRP levels. Up to about 15w you're fine if you put both sections of the cap in series. Making a trombone capacitor seems like it's gonna be really frustrating when you gotta tune it all the time. For transmitting (especially QRP!), you're much better off with a dipole or perhaps even just a quarter wave. For 40m, this means stringing up 10m of wire to a tree or something and creating a good ground system. LimaBiker fucked around with this message at 16:43 on Jan 18, 2021 |
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Jan 18, 2021 16:36
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I have a traditional packet (Ax.25) modem sitting around, and a BBS would be a dream. But i lack the knowledge in antique computer stuff to do anything with it. AX.25 is a pretty good mode for vhf. No idea how it compares to more modern data modes on shortwave. But imagine a shortwave BBS... Today's weak signal stuff is even better. I would opt to use a decent amount of bandwith to get any throughput though. At least something psk63-like.
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Jan 21, 2021 12:07
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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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The old farts are really heavily divided into 'Haha drat are you using a sub-500 euro rig? Don't even bother' and 'Here is 50kg of my old equipment that i haven't used in years! Have fun with it!' Type 1 will then continue to criticize you for using perfectly functional 40 year old VHF/UHF transceivers. I have vacation now! I might try and set up my AN/GRC-9 in the park with a 12m fibre glass pole supporting a dipole, with my motorcycle as a power source for the stupid inefficient dynamotor power supply Also, i might - gasp- use my laptop for running CW cause otherwise it's AM with fairly limited range. It's all a ton of work, though.
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Jul 14, 2021 18:36
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Is there anyone who would like to practice morse together? I'm pretty good at sending - computerized decoders get most of what i send right at 12 to 15wpm with a straight key - but i keep failing at decoding morse in my head. The only way to get better at it is to actually do it, but i get nervous doing it on air, with people who just want a quick QSO and then be gone, or who i can't just DM or whatever. My goal is to be able to be able to receive 15wpm reliably. I can either get on air with 5ish watts on 80, 40 and 30m - or via Telegram or something. My location is near Amsterdam, on 80m in the evening my signal is decently strong at 200 to 500km distance. I've not been very succesful yet on 40/30m.
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Jul 26, 2021 22:24
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Woohoo! Just bought a Yaesu FT-7. Sweet little analog mobile transceiver. First impression: the sound quality is really nice. Quite a few radios have this somewhat harsh sound, but the FT-7 is smooth and very pleasant to listen to. It puts out the 10 watts it's supposed to put out. Stability is a bit wonky, i can tell already that the vfo calibrate potentiometer on the front is scratchy, but when you don't touch it, it's a lot more stable than my FT-101. Now i finally have something i can put in a backpack to escape the mountain of local noise that's strong enough to overload the input stages of comms receivers. Someone on another forum was selling it. They had a FT-7b for 150 (already sold) and this one for 100 euro. Definitely not a bad deal, i think.
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Jul 29, 2021 22:57
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I bought a little Yaesu FT7 a few months back. Made a random wire tuner. Chucked just under 5m of wire in a tree next to my window. Bam. Instantly i hear myself (in cw) on the Spanish webSDR (my location is the northwest of the netherlands). The depressing bit is that i don't hear poo poo from my own receiver. The noise floor (white noise with buzzing sounds every 10khz or so) is just so high, that even though i can get a signal out i can't hear stuff. For a white noise type of QRM, would an X Phase qrm eliminator be any good?
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Dec 31, 2021 19:48
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I have no idea if my bit of wire outside picks up enough 'wanted' signals, because of the big amount of noise. An indoor antenna will pick up plenty of noise, that's for sure. The meter on the FT7 says it's S9 on 80m LSB. I think the FT101 also indicates something in that order of magnitude. I can always go set up the stuff in the park, but it's much nicer to be able to do it from home. E: Ordered one. Will be a week at least before it gets here because of the christmas vacation that last forever here. LimaBiker fucked around with this message at 13:08 on Jan 2, 2022 |
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Dec 31, 2021 19:59
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I have been using this thing to practice sending morse on occasion: https://www.elektronik-labor.de/Arduino/MorseKB.html (if you don't have a german keyboard, change the line keystrokeDE = (usToDE[morsechar]); into keystrokeDE = morsechar; It decodes my hand sent morse flawlessly. Someone could probably use the code and turn it into something computer executable, tack on some existing filters/ALC and use it that way. My experiences with standard computer CW decoders are often bad. Only when there is no fading and the signal is strong, it'll give a proper result. So far CWget was the best, but not good enough to spend like 40 euro on. LimaBiker fucked around with this message at 20:51 on Jan 26, 2022 |
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Jan 26, 2022 20:46
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Limiting which modes you can use on certain bands does make sense. Take the 475khz band and the 136khz band. Those are both about 1 SSB channel wide. Someone using voice there would occupy literally the whole band. 10MHz is also quite narrow, only 50khz. That would fit a few SSB signals, but they still might bother other users. There are plenty of other spaces you can use for wider signals. Almost all other bands are just 'use whatever you want'.
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Feb 2, 2022 20:36
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I've been fooling around with my Yaesu ft7. With just 4m of wire literally thrown over a hedge (a rather tall one, about 4 meter) i could already hear my CW signals on the SDRs in Andorra, Bordeaux, Estland and Cheshire. My own location is close to Amsterdam. Shortwave is pure magic. I do need my tall spiderpole for SSB use. Also, the QRM eliminator works much better with that one. The wire in the hedge picks up almost the same amount of 'wanted' signal as the indoors qrm antenna does. That said, the QRM eliminator is pretty amazing when combined with a 'proper' antenna!
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Apr 28, 2022 22:07
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You guys, i'm pretty amazed. I just repaired a chinese $5 Pixie kit i somehow hosed up a long time ago. I hooked it up to my short wire antenna, and i could hear my CW signals originating here near Amsterdam, all the way in Bordeaux, 900km away. The power going into the antenna is small enough to not even let a little lightbulb light up. How the hell can such a cheap and lovely thing, still get almost a thousand kilometers of range, with such a lovely antenna. Signals aren't strong or consistent of course, but holy gently caress. The TX is stable, no chirp to speak of. It does not offer any tuning, not even 'pulling' the crystal a bit. Which is slightly annoying when you're calling CQ and the someone just doesn't hear you and steamrolls right over you. But gently caress, man, it's a 5 dollar fully functioning transceiver. The receiver is pretty sensitive, but also extremely sensitive to QRM from electronics. And of course there is literally no selectivity. You hear all signals within 7khz on either side of the Xtal frequency. You can adjust the RIT, then memorize the right beat note, and hope you're within the filters of the people you wanna speak. LimaBiker fucked around with this message at 19:25 on Apr 29, 2022 |
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Apr 29, 2022 19:22
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Take care that even in the worst case scenario (such as power lines or antenna poles breaking in a storm) there is no risk on contact between the antenna and the power line. Some power lines create a ton of interference. In some countries high voltage stuff is controlled via power line communication. Whenever i'm listening to AM radio in the car, the 380kV lines in my city create a ton of weird distortion when driving under them. I guess some are worse than others. In my home situation, the VFD of the ventilation system that's fitted to each house in the block, as well as solar panels, are the things that cause the worst interference. In other news, i reached the spanish WebSDR with my little chinese Pixie transmitter. Barely audible signal, but it was there. Antenna was a quarter wave vertical. Distance 1200km! I keep being amazed. People don't seem terribly interested in replying to my CQ's though 
LimaBiker fucked around with this message at 22:13 on May 6, 2022 |
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May 6, 2022 22:07
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Excuse me for kicking the thread, but i just built this! It's a little push pull Hartley transmitter with a DCC90 (3a5) double triode on a small 7 pin base, designed for battery operated VHF transmitters. It tunes the whole 80m band and currently puts out between 0,5w or so, of which perhaps 0,2w is actually flowing through the antenna judging by the very scientific method of 'looking at the dim flashlight bulb and estimating the power it produces'. It should be able to do 1ish watt, perhaps 1,5. It's still a work in progress (yes, that is hot glue), i still have to optimize it and see how much power i can coax out of it, without making the signal too chirpy. After all, this thing doesn't have a separate oscillator! Right now, it is remarkably stable once it's tuned. The chirp is about 200hz which is pretty good for a non crystal stabilized transmitter. Better than my Angry 9. It runs on a 1,2v rechargable battery for the filaments and a 90v inverter for the high voltage. As of yet, i've heard it readable but weak on an SDR 100km away, and detectable and very weak 250km away with a 10m vertical wire in the backyard. The antenna is very non ideal for 80m. It's still daytime here, i'll give it another go when the sun goes down and greyline propagation kicks in Of course, the signals should be much better once i'm done figuring out how much antenna coupling it wants, and how much drive i can give it before the chirp/heating of the tube gets unacceptable. Here's the schematic:  Component values are here for 160m and for bigger tubes. LimaBiker fucked around with this message at 19:25 on May 9, 2022 |
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May 9, 2022 19:14
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Paul MaudDib posted:Any recommendations for stealth antennas? I used to have a VHF tv antenna so I could probably get away with something similar to that, as long as it’s not like “lol giant antenna” nobody will probably care. I could also probably get away with a vertical antenna (flagpole, vertical helical if that’s a thing, etc). I’m interested in going as low frequency as I can get, 20 Anything is an antenna as long as you throw a loading coil and a tuning capacitor at it. Throw a piece of wire into a tree and tune it, and see what happens. Seriously, i have 4m of wire thrown in a conifer that's sitting outside of my window, and with my 500mW Hartley transmitter on 80m, i can occasionally hear that signal 150km away. With modern, sub noise floor digimodes you can get much further, even with such a objectively poo poo antenna. I have a 12m long spiderpole in the backyard that i occasionally extend. Shortened to about 10m, it's a decent quarterwave antenna for 40m. So far, with 10w CW, i've reached a LOT of european WebSDRs. Because i'm lovely at receiving morse, i haven't made too many QSOs though. Haven't tried much SSB yet on 40m but Belgium i reached with ease. It also works on 80m at full lenght, though less efficiently. I had a decent SSB QSO with a guy who was using a Wireless Set 19 on his side, modified to transmit a rough approximation to SSB. Distance 400km or so, power on my side 10w. I haven't managed to make the vertical work on 20m and higher yet. My tuner is pretty limited for those frequencies. But on 20m, i've had great results with a magloop antenna, 3m in diameter. I could just strap that one to the fence in the backyard when i needed it, and put it inside when i didn't. If you have no metal coated isolation in your attic, a loop will also kinda work there. Neither have i had much luck on 160m. Antenna efficiency is again pretty bad at those wavelenghts, and i couldn't compensate by stuffing the full >100w of my FT101 into the antenna because the tuner flashes over at 20ish watts because i just used broadcast radio tuning caps. Start out by building a simple antenna tuner and then experiment See if you can find a flag pole that's about a quarter wavelenght in height. Make it a glass fibre one and you can just hide the antenna wire in the core. If your house is tall enough, you can mount a metal drain pipe on isolated spacers against the side of the house, and use that as an antenna element. If you have a wide house, then you can try using the gutters as a radiating element. It's hit or miss with those kinds of things, but especially with narrow band modes like CW/FTsomething/PSK31 you can have fun results with little effort. These are all examples of 'least effort' antennas. If you put in some 'real' effort, you can get much better results. LimaBiker fucked around with this message at 21:43 on May 12, 2022 |
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May 12, 2022 21:26
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 Bought a new toy! A TinySA spectrum analyser. The operation is easy, the specs are incredible for the 70 euro price point. But i still have to learn how to probe stuff correctly. The maximum input power is 10mW (and you kinda wanna stay well below that). I'm used to my oscilloscope which is totally fine with putting 50v into the input. I'm very happy i bought this cheap thing because there's quite a lot to learn about working with spectrum analysers. Shown in the picture is the picked up signal from my 1920s style push pull transmitter. I have yet to figure out if the 3rd harmonic is indeed that strong, or whether the carrier is not as strong in the spectrogram as it is in reality. A whip antenna is not the ideal tool for proper measurements.
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May 14, 2022 20:47
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Ensign Expendable posted:I don't know if this is the right place to ask, but I figure you could give me a lead at least. Where do you live? It makes a big difference in the availability of parts. On ebay you can find a lot, but shipping can get expensive if you live in EU and order from the USA. There are several dutch shops like this one that have parts and complete sets: https://www.quartermaster.nl/index.php/geallieerden-ww1-en-ww2/radio-communication-equipment/ws-19-receiver-mk-ii.html Don't rip apart a complete WS19 though. Unmodified, unrestored ones are getting harder to find.
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Jun 6, 2022 14:15
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A big reason why baofeng & co are not approved for any transmitting use by multiple countries, is that the spectral purity of multiple models is abysmal. https://www.youtube.com/watch?v=EjEl6dciLS0 40dB is barely passable (though still illegal), 34dB is really bad.
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Jun 8, 2022 21:08
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Here's a fairly simple PLL controlled one: https://nfor.nl/radioforumservice/index.php?p=artikelen&sub=artikel-am-pll-2-1 Be aware it's designed for the 9kHz channel spacing - you'll probably need to change some divider stuff if you want it to adhere to the 10kHz USA channel spacing.
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Aug 25, 2022 09:48
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If you have a lot of local interference, i can recommend a X-Phase QRM eliminator (google it). They work well on the condition that you have an antenna that receives the signal + noise, and a little extra one that doesn't (or only barely) receives the signal, and a lot of noise. It doesn't work as easily due to a few seconds delay and no blocking of the received audio during TX, but you can also try a webSDR from https://www.websdr.org (preferred) or http://kiwisdr.com/public/ (in my experience they're less sensitive). The delayed signal you receive from yourself means that if you do phone or CW, you'll have to turn off the sound manually during TX because it's extremely hard to speak/key when you hear your own signals 1 or 2 seconds later. If your SWR is 1:11 or 1:20 you're not gonna transmit anything. 1:1.1 or 1:2 is fine. At 1:2 you'll get a 12,5% weaker TX signal or so i've heard. But with a 50 ohm output and a random wire antenna, even with the most rudimentary of tuners it's pretty easy to get an SWR of 1:1.7 or so.  Start with 40 turns of 1mm wire, that'll work for 20-80m. Capacitor is about 300pF, a broadcast one (air dielectric) works fine up to 20 watts or so. I've been using this tuner with decent results. Works fine for whip antennas and half wave-ish random wires. You do need to add taps on the coil every 5 windings or so, a shorting clip from the coax input on the left side with which you can bridge part of the coil, and your antenna goes either all the way on the right side, or clipped onto one of the taps. I can highly recommend inserting a light bulb into the antenna wire so you can actually see when you get antenna current. An SWR meter can display good SWR sometimes, while there's absolutely no antenna current flowing. Bridge the bulb when you've roughly found the right spot. LimaBiker fucked around with this message at 08:17 on Oct 26, 2022 |
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Oct 26, 2022 08:08
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Just to add: An swr of 1:10 means that 66% of the power you normally send to your antenna, is now lost as heat in your output valves/transistors. Many SWR meters don't have scale calibrations past 1:3, because past that point you're pretty likely to burn out a transistor/valve, unless it's a QRP device, or there is protection circuitery against high SWR. It is safe to assume all modern and semi-modern ham radio gear from reputable brands is protected. But old valve equipment like a Yaesu FT-101 will appear to operate fine, perhaps hum a bit more than normal, but you will eventually burn up the final tubes which are getting expensive...
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Oct 26, 2022 17:24
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I tie my fiberglass pole to a fence post with a short luggage or ratchet strap. Spiderpole has a nice little harness you can slide over a pole that you then can attac guy wires to. I have a big parasol stand that screws into the ground that can secure the base of the pole. I'm currently on my way to a hamfest by the way - in Zwolle, the Netherlands. Hoping to find WW1 trench radios. Not too big of a chance of finding one but i've been bummed out not getting one, ever since i actually found one at the age of 15, 15 years ago. Couldn't afford it back then, neither did i have even close to enough knowledge about operating an actual spark gap transmitter in a way that doesn't get me in trouble. LimaBiker fucked around with this message at 10:12 on Oct 29, 2022 |
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Oct 29, 2022 10:08
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Back! The market was a bit odd, there were many sellers who registered but didn't show up, so many empty spots. I expected more sellers. But regardless i found quite a nice load of goodies!  - Two 1920s tubes and a big coil to make a 1920s style transmitter (RE134 3w output triode and A425 small signal triode - A reflex klystron just because it was in a 1 euro bin - Some 1970s LED pixel displays - A free LCD module - Some free rotary switches - A reel of antenna wire - 4 big egg shape porcelain isolators - Some RFC's - A pair of used but beautiful Hirschmann KLEPS measurement probes - a MFJ 1,8-30MHz antenna tuner. I almost bought all the separate parts to build a tuner myself (roller inductor, big variable capacitors etc) spending about 100 euro on the parts and then having to figure out how to make a nice enclosure. But then i found this thing. As much as i appreciate the art of diy radio'ing, i just couldn't push myself towards spending just as much money and then having to build the thing myself... - Tiny RC car, about the size of a mouse. Hope the cat likes it. - CRT tester-rejuvenator. - Some old headphones.
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Oct 29, 2022 17:39
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I will be using it with a too short antenna on 160m, but probably with no more than 50 watts or so.
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Oct 29, 2022 21:56
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Soo i'm gonna make a little bit of a ground/radial system next to my house. But i gotta feed in the ground wire over about 4m length, to the first floor. What do you think is best - a stretch of old vacuum cleaner power cable (2x 0,75 or 1mm^2), or some old RG58u coax with the core and shield connected together? The coax is pretty thin, but the skin effect should send most current through the braid, i think. The ground system will be some 4m long radials (our front yard simply is no bigger) and a grounding rod (directly under my shack window) connected together. E: found another length of better quality RG58 and used that. LimaBiker fucked around with this message at 16:00 on Oct 30, 2022 |
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Oct 30, 2022 14:21
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Well, the random bit of wire even works on 160m, kinda. Made a CW contact with a british guy in Tatcham, 75km east of London - from Amsterdam, the Netherlands the distance was about 400km. Hand trembling on the key, for some reason morse makes me hella nervous. Guy was patient but i didn't understand half of what he was saying, i really need to get better at it... But i feel that's pretty hard with people you don't know.
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Oct 30, 2022 21:26
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Consumer level tube stuff (the Hallicrafters S-38 or S-85 and such 'general coverage' receivers) are lovely to see and use for broadcast and AM stuff, but for SSB and CW sorely lacking in stability if you use them for 14MHz and higher. On 21MHz you're literally constantly adjusting the fine tuning or BFO pitch to keep up with drift. They don't usually have crystal filters - expect 10kHz bandwidth. Actual ship's receivers are absolutely fantastic. The sound quality is a lot better than from modern receivers. The sensitivity is excellent, and of course once refurbished, they will last another 50 odd years. They're often made to be serviced - my Philips BX925a has plug-in power supply capacitors - so although literally all of them need to be checked for leaky paper capacitors, actually doing it is often easier than in broadcast receivers. In my case the narrowest filter is 900hz wide, and the 2nd narrowest is 2,6kHz (at their -6dB points). So they're on the wide side for CW use. However, the sound is very 'mellow'. Even although you're hearing multiple CW signals together, it's not a grating sound. In my specific case - and that was a complaint from the users of these sets in the 1950s - the receiver isn't too stable, despite having a stabilized HV power supply. If my 2kW room heater that's running on the same circuit clicks on, i can definitely hear it drift a few hundred hz. On a stable supply, it's pretty solid once warmed up. Because of its large thermal mass, it is less sensitive to room temperature changes than my (mostly) transistorized Yaesu FT-101e. That thing jumps a few dozen Hz already if i just blow on a circuit board. If you go further back in time, to before WW2, you'll still find TRF receivers all the way up to 1940. They typically were set for one frequency, then the controls were locked and left there for as long as possible because they require some skill to tune properly. Quite often they don't have a frequency calibrated dial - only a logging dial, where the operator would write down the number on the dial and the station it corresponded with. My BX925a has a roughly calibrated MHz dial (per 100 or 50kHz) and an extremely accurate logging dial. This is actually pretty convenient - you can write down in your log book something like 'Roma Radio IAR 21552' meaning band 2, division 15, subdivision 52'. With the band switch you set it to band 2, with the motorized tuning you zoom towards division 15, and manually you scroll to subdivision 52. This can all be done in seconds. One subdivision is about 1kHz though there is no strict relationship between how many kHz something is, and the size of the subdivisions. Personally i don't worry too much about the high voltage. As long as you exclusively poke at things with your multimeter probes you're not gonna get zapped. If you are dumb and start moving the chassis on your bench while it's plugged in, you're gonna get zapped sooner or later. In 15 years time my zap counter is 1. Tried to shift the chassis of a broadcast receiver i was doing measurements on, grabbed the bottom socket contacts of the magic tuning eye. Wasn't a bad zap - i reckon i grabbed it after a bunch of current limiting resistors. Grabbing the full high voltage, however, will hurt like a bitch. LimaBiker fucked around with this message at 16:09 on Nov 14, 2022 |
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Nov 14, 2022 15:48
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Measuring such a DC voltage is very strange. Unless there's lightning in the area and you measure static charge (The voltage can then be hundreds, sometims thousands of volts). Perhaps connect a 47k resistor parallel with your (i assume digital) meter and see if the voltage drops to nearly zero. Of course, never do such measurements when lightning might roll in. Grounding the radio to the power strip is good for safety, but useless as an RF ground. The whole mains ground system has a way too high inductance to be effective as an RF ground. Hook up the transceiver to a dedicated RF ground system. That can be counterpoise (isolated wires running over the ground, or buried a few centimeters underneath) or a good ground rod system. You connect that ground to the ground lug/screw/terminal on the transceiver. Use as short a length of cable as possible. I use old but decent quality TV coax with the braid and core connected together.
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Jan 11, 2023 22:06
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tiaz posted:man, same. my real problem with CW is there's no letter/word separator. people say you get used to it but I've always bounced off the attempt before that happens. If you can't separate letters or words from each other, the person you're listening to is probably sticking the letters and words together. You could consider asking the person you're talking to, to use Farnsworth spacing - letter speed stays the same, time interval between letters gets bigger. That's fairly easy to do. Most morse trainers can also do Farnsworth spacing.
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Mar 3, 2023 20:48
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The best work shops grow organically. But the start is always a nice workbench with plenty of outlets, a soldering iron and some fine diagonal cutters. I bought a big ex-Philips Natlab (physics lab) work bench at the age of 16, and i'm 31 now. One of the best things i ever got. I can't imagine life without a proper work space.
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Mar 20, 2023 10:46
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Oh yeah - and a 3rd hand.
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Mar 22, 2023 17:24
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I found a thing at the thrift shop:  A handheld emergency radio telephone. Between 5 and 2w of AM power on 2182kHz. It has a huge 2m long whip antenna, and a reel of wire you drop into the water as a ground. Range quoted varies between 40 and 80 nautical miles. It generates a carrier, and the receiver board works. However, the audio amplifier is dead so no modulation and no received sound through the earpiece. I'm thinking about what to do with it. I think it should be doable to tune it down to something like 1850kHz, that's only a 10% down tuning step. However, both TX and RX are crystal controlled. Contemplating what's the easiest way to go. I'm considering a mixer to mix 1850 to 2182 for the receiver, so i don't have to change anything on that board and perhaps even be able to tune the RX. The TX just needs a stable oscillator, which isn't too critical for 160m AM. But if i make it a VFO, then i also have to be able to tune all the resonant circuits. A fixed frequency makes for harder operating. I can't choose another frequency if it's busy, after all, or respond to people calling unless i'm within their filter. The internals are pretty crude (but very sturdy - the TX board is 2 or 3 times the thickness of a conventional circuit board) with (for transistor equipment) uncommonly huge AF transformers: 
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May 3, 2023 13:12
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