/diy/ - Do It Yourself

i am putting up a fan dipole, 80/40/20, should i use a 1:1 balun, or just hook it up directly to coax?

Here's canada

>>1355294
thanks, ill add that to my folder

So I tried to build a simple schottky diode detector AM radio that feeds a small headphone amp, but a couple of metres of straight wire didn't seem to work as an antenna; there was no signal on my scope aside from some 50kHz noise and mains. What sort of quick-and-dirty AM antenna should I be looking to make? I've got a few dozen metres of 28ga enamel wire and a cardboard box I could wrap it around, but I've seen a few different variants of the loop antenna out there. Namely some with a centre-tap, some with a capacitor, and some with coupled windings. Should I be trying to get an antenna that works as my inductor in my tank circuit, or otherwise to have a resonant antenna?

I've calculated that I get better inductance per metre of wire with a larger diameter, though the returns are quickly diminishing once past half a metre of wire or so.

Any Indians present here? I wanted to get my amateur radio license in India but the there's a shitload of bureaucracy and it takes a year from when you write the exam to actually receiving the license

r8 boys

>>1355379

>>1355381
also what should i add next

>>1355382
one more i forgot to add

>>1355304
10m or more, straight, not grounded. doesn't have to be resonant, but it should be long
>50kHz
is your detector cap big enough?

>>1355391
>>1355382
>>1355381
>>1355379
Hoarder/10

> also what should i add next
Something you'll actually use instead of a bunch of 70's/80's era junk that impresses no one.

>>1355382
may I suggest something homebrewed

>>1355396
>70's/80's era junk

>>1355374
If that is as good as it gets may as well get it done for next year.

Have been interested in some of the /diy/ stuff there for its minimal designs.

>>1355304
0. Have you confirmed there are stations at proper frequency range close to you?
1. Like the other anon said, the longer the antenna is, the better. 2m antenna is nothing for a crystal set.
2. Have you grounded the radio properly?
3. While schottky diodes can work well, it does not mean that any random power schottky is ok. Are you sure your diode is ok?

>>1355401
Obviously you think they're awesome since you keep hoarding them, but it does not mean they impresses the others. In particular, why would others care about your run-of-the-mill consumer electronics?

>>1355393
470µF high frequency choke + 18-280pF cap. It/s pretty perfect for what I just happened to have lying about.

>>1355412
1. I'm in the middle of the big city, so there's bound to be.
2. It was an electrically short "monopole", I've got no room to lay a quarter-wave except for maybe dangling one out my window (on the seventh floor). But I thought I'd get at least something. Not sure how having an antenna against a wall would affect the reception but I'm not doing that anyways since my neighbours likely won't take it well.
3. I have a roundabout reference to ground through my amp's voltage rails (they're relative to the building ground from my PSU) but I hardly have a ground plane about my antenna. This is another reason why I suspect a loop would go down better; as I understand they don't require a ground plane.
4. Well I could try replacing it with a Ge diode, it was just a spare schottky that I had lying about. I imagine you're referring to low-amplitude signals and frequency, I guess I could test a few diodes at 100kHz+ and voltages below 0.3 and see what I get on the other side, but I thought the point of a good antenna was to get a signal amplitude above your diode voltage.

>>1355428
>470µF high frequency choke

>>1355431
I mean Henries.

>>1355428
>except for maybe dangling one out my window (on the seventh floor).

The medium wave pirates used to use this with the buildings ground strap as an earth. They would string the wire out to a tree on an angle. If you have power lines down there look out.

As one who has played with crystal sets I never got much out of them with less than 30 metres of wire. I only ever got the 50 kw stations which had TX sites 60km away.

>>1355434
Well is there any reason not to loop a dozen metres of wire about a cardboard box instead?

>>1355433
if you have a shitload of magnet wire, maybe you should roll your own air-core L and take the mystery core mix out of the equation

>>1355436
Only if its tuned as a magnetic loop antenna.

>>1355439
http://makearadio.com/crystal/19.php

I need a nice small portable wideband antenna for a USB SDR, hit me.

>>1355442
Upper and lower limits?

>>1355437
Just measured it, 0.49mH by my component tester, 0.47mH nominal. Since anywhere from 0.34 and 0.53 mH will work, I think I'm fine.

>>1355439
>>1355440
Ah, so the loop itself acts as the tank circuit's inductor. But calculations tells me that the inductance of that loop antenna is on the order of 6µH, far too low to resonate with the 365pF capacitor at 500-1500kHz. Instead that would resonate at 3MHz or so at maximum capacitance, and much higher for the minimum capacitance. Does the centre-tap somehow increase the perceived inductance, or are my calculations that off? Or do inductive antennae resonate differently?

>>1355453
Looks like I can rectify signals down to a few 10ths of a volt with the Ge diode. Apparently it's either a 1N60 or OA91, the latter of which is pretty ancient looking.

Just finished a QRP Labs kit, have to finish tuning and making final adjustments. Don't know a damn thing about electronics. The kit was very easy to assemble, only screwed up one component during the build.

>>1355495
wish i knew CW. that looks pretty neat
only $50?
how long did it take?

>>1355428
>I'm in the middle of the big city, so there's bound to be.
It depends entirely on where you live. For example, there are exactly zero medium wave stations left in my country. Building a crystal set is a waste of time here.

>>1355280
Thanks for starting a new /ham/ general. The FAQ has been updated since yo made the template, we are now at Preview 6. Linking to the catalog makes it easy to see the latest version:
ftp://collectivecomputers.org:21212/Books/Cyberpunk/Tech/Radio/

It seems username and password no longer is required.

>>1355495
Congrats. Now you need a paddle.. :)

>>1355495
..and a good antenna.

>>1355523
would you need a 4:1 on a full loop?
id also like to run about 700 ft in a rectangle shape and see what i can hear.

>>1355287
1:1 if using coax, none if using ladder line.

>>1355381
Nice swan meter

>>1355424
>t. /g/ poster
Arch rulez!

>>1355443
ELF to Y should be sufficient.

>>1355443
ELF to γ should be sufficient.

>>1355537
Delta loop is a full loop, same as a quad. For mono-band use you need no balun, a coax matching section works too. Z of the loop is about 110Ω and sqrt(110*50) is about 75Ω. The length is (l/4)*vf and the velocity factor of the 75Ω coax cable is typically 0.66 (PE dielectric).

Following up from last thread:
>>1349124
>What do people speak about on CW? Or it is used for QSOs only?
You can easily use it for chatting, after all it is faster than texting/SMS: https://youtu.be/pRuRE-Bwk1U
>I mean, how is CW-shitposting?
OK, this is so many years ago now that it can be told:
>be me. in uniform. in the military
>On exercise, running traffic using voice. It is late, it is boring and we are getting tired.
>Suddenly: a burst of Morse!
>Immediately awake, perking up, locking onto code. It is a mild case of poo posting. Woo hoo!
>Notice higher officers around. Noticing none of them are Morse capable. Keep straight face.
>Another burst of Morse!
>A few hours later about half the traffic is Morse, yet keeping exercise traffic up still. Higher officers only care about getting (real) traffic through. Still suspicion is growing
>And they sure had good reasons for it!
>Exercise over, everyone pretending Morse never happened.
Telegraphists flouted a lot of rules but we were accepted as long as we delivered and that we did, especially during heavy jamming.
Officer 1: "They really should dial back the jamming; it just brings the exercised to a grinding halt!"
Officer 2: "Really? We got every traffic through" . o O ( Smirk )
Officer 1: . o O ( Groan! )


OK, enough reminiscing, back to thread.
>Also I have a question about FAQ. There's sentence:
>>And make no mistake, you will be found. And recorded, voice prints archived for future use.
>but
>>A properly trained military Morse code operator will know how to transmit to the target without being caught by enemy intelligence
>So, are Morse code operators caught or not?
There are two different issues here: one being recorded and (roughly) located, the other being actually caught. This is literally the difference between life and death.
>I guess, uncatchable one must have 5 years of military education?
You need wide training but it probably takes less than 5 years.

>>1355502
Start to finish about 5 hours, really took my time $50 was worth the entertainment alone. Kept me out of trouble for a couple days. The transformer torrid was the biggest PITA. Slipped out of my fingers and lost track of the wires right before install. Checked continuity and order like 8 times before I soldered them in place.
Been slowly trying to teach myself CW and I hope the decoder will help. Already have a decent antenna strung up from another project

This might be a bit of a long shot, but does anyone know where to find getter rings?

I want to get into making simple vacuum tubes, and then use those to make a radio, and I can find everything I need to do so with the exception of the barium getter rings.

The only place I've seen mentioned to get them is from other vacuum tubes, but that kind of defeats the whole point if I have to buy tubes anyways.

>>1355592
Ask F2FO (Claude Paillard)

>>1355640
You know, I was watching his videos, but I don't think I saw him use getter in any of his tubes.

I mean, it's not strictly needed, but it makes achieving the proper level of vacuum a hell of a lot easier, and greatly increases the filament lifespan.
I'd rather not have to rebuild all of my tubes every year.

>>1355660
Well, you solved your own problem: pump better, omit the getter.
Assuming you aren't willing to pay $lots, you can try your luck with titanium. There's also the azide process, but if you can't buy getters, then you probably can't get barium azide either.

Or just take getters from existing tubes.

>>1355592
>>1355660
Titanium is a highly effective getter, and you can buy it in the form of tubing or wire to make your rings. Unlike barium it's also air-stable, so you don't have to worry about shelf life. You can either flash it like a fuse (for thin wire) or use it as a bulk getter (for thicker rings) in which case it becomes reusable, e.g. if your tube gets gassy over time you can reheat the getter to clean it up again. The only downside is that it's fairly resistive so it doesn't pick up induction heating very well, but I used one of those 1kW modules from ebay and it worked well enough.

Check out some of the earlier projects on my site if you want more details, the stuff from 2016 is mostly tube-related:
http://simplifier.neocities.org/

>>1355280
I'm getting rid of all my ham stuff because the hobby is dead.

>>1355665
I don't think you get quite how strong of a vacuum you need.
For tube to live a good long life, you want about a 10^-6 torr vacuum.
A vacuum pump that can reach that level of vacuum is going to cost thousands of dollars.
And even if you achieve a 10^-6 torr vacuum, you still have to account for components outgassing or air seeping through where the glass was sealed around the wires.
In short: Yes you can make a tube without getter, but they won't last long.

>Or just take getters from existing tubes.
Yeah, no. That's going to be expensive.
You don't see broken tubes for sale, and working tubes are all marketed for audiophiles.
Besides, I would just be taking a perfectly fine tube and using it to make an inferior one.

>>1355678
>Titanium
I actually just started looking at that.
I was surprised how cheap titanium wire was on Amazon (like $12 for 4 yards of it).
One other thing I saw was zirconium, but that shit's outrageously expensive. I think the lowest price I found was $160 for a meter.

>http://simplifier.neocities.org/
Oh! I remember seeing you featured on hackaday.
Nice work!

>>1355682
hook me up

>>1355687
>$12 for 4 yards of it
That's actually pretty expensive, I'd check on ebay instead. IIRC one time I found 0.8mm Ti wire for $0.10 a foot. That's a good general-purpose diameter, by the way. Makes good feedthroughs and getters, and doesn't burn easily.

>>1355687
>>1355713
My bad, it was $0.20 a foot. I bought mine through ebay, but looks like the seller was this place:
http://theringlord.com/cart/
They've got a decent selection of sizes, and I can confirm their wire works for vacuum tubes.

>>1355714
Thanks!
Do you also happen to know where to find tungsten wire?
Like, not thin tungsten wire for the filament, but thicker tungsten wire for the feedthrough.

>>1355567
can i make that horizontal? or would that not work.
im inna woods, on of my ideas is to just use a bow and some strong line and shoot it over some trees, and drag the antenna through that.
i really like listening, so i figure ill try that out. just waiting for the weather to get a bit better so i can invite friends out to help

>>1355741
Just ebay. Never found any particularly good deals on it, tungsten prices were usually pretty consistent. A lot of people will say the quality of the wire matters to avoid splits, but I found that cutting slowly with dull wire cutters eliminates splitting entirely (by pinching off the wire rather than cutting it), so I just used the cheap chinese stuff. IIRC I had the best results with 0.3mm tungsten in borosilicate glass.

Another option is to use neon sign tubing and make your feedthroughs with titanium. Titanium is COE-matched to most soft glasses and sticks well if you get it hot enough; I've made feedthroughs in light bulbs and beer bottle glass before. If you're already set up for borosilicate (oxy-fuel torch) don't bother, but it's an interesting possibility if you want to start on the cheap.

really wish this board had IDs

>>1355743
>horizontal?
Yes, you can, but distance to ground influences radiation pattern. GU3WHN has a pdf about the antenna.

ITT: LARPing idiots are who are trying to make their own tubes in order to make a radio.

Transistors were invented for a reason, you fucks.

>>1355804
I agree, all creative endeavors must be subservient to the will of consumer electronics companies.

>>1355796
i can only get up about 40 ft

>>1355811
>about 40 ft
erm.. that would be about erm.. 12m? that's more than l/4, just do it.

>>1355804
You do know that tubes are still commonly used in broadcasting because it’s easier and cheaper to make a high powered vacuum tube, right?
I bet you haven’t even heard of a klystron.

Also, are you ever going to stop being a faggot and stop shitting on other people’s projects?

>>1355443
The dongle goes from 24MHz to 1850MHz not sure where the interesting stuff is around here.

>>1355510
Oh yeah, some countries are/have already phased out AM. Which is odd, because it should be pretty narrow-bandwidth if done correctly. But there's like 15 stations here.

>>1355822
Nope. Do you dill holes have plans to homebrew a couple hundred kW transmitter? No? I think making your own tubes is unnecessary, but let's pretend that you are actually going to do this. Don't forget, a true DIYer would mine the raw materials using tools that were fashioned by said DIYer.

>>1355816
id like to put one up for 80. have a tuner, but it has a 4:1 balun in it. not sure if that is just for ladder line or line in

>>1355875
jesus, i hope you get aids

>>1355822
Your huge transmitter tubes aren't very relevant to this diy tube discussion.

>stop shitting on other people’s projects?
So, what exactly is the project here? That simplifier guy and the old French guy apparently just wanted to experiment with shit and re-create old things, but you sound more like you're trying to run a fucking factory, producing useful tubes for various projects - while penny-pinching and nigger-rigging shit to the extent that even taking getters from $1 used tv tubes is too expensive. What are you trying to achieve and why?

>>1355865
The AM stations here (and in the neighboring countries) served mainly people outside the country. They weren't profitable and relied on tax money to stay in operation. Then the gubbimint found better uses for tax money.

>>1355396
>>1355424
>>1355804
>>1355875

did mummy overcook your tendies and buy the walmart brand mt dew?

>>1356060
haha. that basement dwelling nigger is pretty mad
tendies must have gotten burnt

>>1356062
>>1356062
> MEMES XDDDDDDD

>>1356065
nigga you is WOKE AF

>>1356014
If I can figure out how to make my own virus, maybe.

>>1356060
New here?

>>1356096
>>1356095
this is cute and all, but can we get back to talking about radios and electronics?

>>1356108
He probably won't shut up until no one even bothers talking about making anything more complicated than a dipole antenna.

>>1355495
Design seems interesting. Curious about the bands, are those fixed when you buy the kit?

Seems the ADC sampling speed is a bit low, perhaps 7kHz, or are there two ADCs?

>>1356160
it looked to me like they were one band each.
unless he got something different, what it seemed to be on their website

>>1356112
Maybe try something in between making a dipole and making your own vacuum tubes, smart-ass.

>>1356185
What is the best way of going full band HF? Banks of filters and superhet?

>>1356196
with that thing? im not sure
this is what id go with otherwise

>>1356208
I haven't decided yet. My interests are in CW and digital modes, HF and below. Any comments on this chart?
http://www.elecraft.com/KX3/KX3%20vs.%20IC-7300,%20rev.%20A6.pdf

>>1356211
shit, i thought the kx3 was a lot more then that.
im happy with the 7300, but i am new to HF. its really simple to use, everything is right there.
kx3 looks like it would be really nice for on the go work or in your truck. id like to pick on up this year to try it out.
but id never get rid of my 7300

>>1356211
Do you have a license or any experience?

>>1356189
>Making vacuum tubes is hard.

Nigger, you can make a vacuum diode from a car tail light.
I've done that and want to do something more interesting.
I can get all of the equipment I need for about $350, and supplies for another $50.
All I need after that is some practice making them.

It's a hobby project, for fun, that's right FUN.
You understand the concept of fun, right?
It means I'm doing this for my own entertainment and education.

>>1356221
I live next to a major power distribution facility and I just discovered another line for rail power at 16 2/3 Hz. I will need a mobile rig to get anything useful since I have to go quite a distance.

>>1356223
>Do you have a license or any experience?
Yes to both questions. I am the one who did Morse in the military. I have been inactive for many years and thought it was time to brush up on old skills. And I have maintained my licence all these years. As for "experience", mine is a tad specialised.

>>1356227
that guy is a fucking cunt. every post hes made sounds like a woman crying while on the rag.
what youre talking about seems pretty interesting, but its way over my head right now.
only been into ham/electronics for a little over a year now
>>1356231
that sucks.
just let the FCC know, im sure theyll get right on it!
you wouldnt want the 7300 for anything portable. its not as big as my older radios, but its still pretty big.
found a nice padded case at sams club that it fits perfectly into for 20$ for when i travel.
>As for "experience", mine is a tad specialised.
go on.....

>>1356227
LARP

>>1356233
>>As for "experience", mine is a tad specialised.
>go on.....
Well, most of it is boring to tell, like how to evacuate quickly and also silently and later setting up a new station in total darkness. Some of the stories border on the unlikely like this one >>1355570 though there are many more that would appear even less probable. I did some reminiscing a while ago and concluded I have enough stories to write a book about stories I heard and another about things I experienced myself. A few involve more explosives than we should have used.

It seemed quite natural at the time but in hindsight we were a peculiar lot and that went all the way up to the commanding officer.

>>1356012
4:1 is not really needed for a full wave loop, 2:1 would be enough. Feed line is difficult, there is no 100Ω twin lead. If you only want mono band 80m the l/4 match is the simplest way. Pic: a certain quad ratio has 50Ω.

>>1356249
part of me really wish i served, i would love the skills and experiences. one of the last thing i remember my father telling me was to never join and be a slave to the government. i had no clue what he was talking about at the time. he was a marine in vietnam, died from cancer years ago.regardless, i still wish i joined
im sure the book would be a good read. setting up in total darkness sounds like a real pain in the ass
>>1356287
the 50ohm one is what i have the space for.
i measured and i have space for about 700ft of wire in a rectangle. not sure what i should do with it, i enjoy listening to shortwave, and cruising through the bands. i put up a 270 foot dipole fed with ladder line, cant hear a fucking thing out of it. not sure what i did wrong. was just for receiving. wish i could build a giant discone for HF

>>1356160
probably different component values for the band pass filter on the input per band
>7kHz
the only ADCs are in the AVR. it's a direct-conversion CW-only rig, by the looks of it. can't think of a reason it would need much more than 7kHz

>>1355857
A simple telescopic rod would be a good starting point. Its a compromise antenna but if you want portable....

>>1355865
Its the mainstay of emergency broadcasting here. FM has proved less than reliable in fires as its mountain top and the sites are more likely to get burnt. One major FM site failed totally in a fire some time back.
>Fire cut power
>Backup generators fired up
>Roller doors went up for radiator airflow
>Sucked the fire right in the door

One tech was on site and survived.

The next day they were back up at 2kw on a transmitter and generator they drove in. They spent the next week or two scrubbing ash and carbon out of the main transmitters which were shut down manually in time to save them. The main generators got replaced because we wasn't going to risk his life going outside to the next building to shut them down.

>>1356160
Yes you order the band you want, once power is applied you set the radio to the band you built with the internal programming of the ATmega328 chip (I douched mine right out of the box). So far everything does what it's supposed to do just need to connect it to the antenna. May consider getting another kit and plan a fancy case. I'd love to have the knowledge that some of you have

>>1356053
So what are the MW bands used for in those countries? Or are they left open to listen to stations of neighbouring countries?

>>1356360
>Its the mainstay of emergency broadcasting here
Damn better be, making a tiny am receiver is easier than an FM receiver on the fly. Though I guess there's bound to be an FM "foxhole" equivalent using one of those RC demodulators, with a cup of water as a resistor or something.

>>1356499
just tune your foxhole AM receiver off frequency and hope no neighboring stations are operating

>>1356511
I don't follow. Is this one of those unintentional modulation effects that sometimes causes FM stations to have an AM component via interactions with surroundings or something? Still, foxholes aren't easy to tune.

>>1356541
>aren't easy to tune
point taken. anyway
>Frequency variation on one sloping side of the radio tuning curve gives the amplified signal a corresponding local amplitude variation, to which the AM detector is sensitive. Slope detection gives inferior distortion and noise rejection compared to[] dedicated FM detectors that are normally used.

>>1356544
Ah, that does make sense, just like the low-pass-based demodulator. While you'd need to redo the foxhole geometry to get those frequencies that would probably work perfectly fine. Maybe just have a switch and a seperate coil.

>>1356343
>the only ADCs are in the AVR.
That is what I suspected.
>it's a direct-conversion CW-only rig, by the looks of it. can't think of a reason it would need much more than 7kHz
From the description it does digital modes too including WSPR. For those I wondered if 7 kHz was enough bandwidth., especially as others use 44 kHz on each channel using stereo audio ADCs.

With more bandwidth/channels in the ADC it might be possible to do direction finding using two antennas using a similar design.

>>1356499
>So what are the MW bands used for in those countries?
It's an international broadcast band and in good conditions even weak transmitters can have quite a range, so at least here the MW band is simply unused.
I haven't seen an FM band version of the crystal set, but I've seen one super-regen (one transistor) FM receiver. It was based on slope detection.

Anyway, did you get it working? If not, check your coil while you're at it. It isn't unusual for ready-made coils to have uselessly low self-resonant frequency.

>>1356561
ahh, missed that part
>enough
WSPR has only 200Hz bandwidth. if they sampled at 7kHz they could do 16x oversampling
other projects seem to be using more powerful SoCs which have I2S ports, so PC audio codecs are a natural choice for cheap, fast, high dynamic range, and the feature possibilities that come with that extra bandwidth like panadapters, dual watch, etc.

>>1356564
Well I'm not making a foxhole but a normal "crystal radio". I don't have a high-impedance earpiece (should probably get one) so I'm just using an opamp on a bit of perfboard instead, which works fairly nicely by itself. I just have to try the circuit with an actual MW loop antenna instead of a 2m monopole. Just a bit busy with class at the moment.

>>1356587
>should probably get one
Get at least two, one for each ear. Listening with both ears sounds much better. Have two 3.5mm output jacks in parallel. If stereo, leave R (ring) unconnected. Make sure the earplugs are not anti-phase (left and right but no center). If they are (50% chance), just swap the polarity (tip and sleeve) of one output jack. You can use crococlips to select the best taps on the coil.

The audio quality of the piezo earplugs is worse than that of an AM station and a better way to listen is using (sensitive) 32Ω earphones and an output transformer for impedance matching. You will be amazed how good your local station sounds because you receive the full bandwidth, not only the part the IF filter of a typical AM radio lets through.

>>1356307
>part of me really wish i served, i would love the skills and experiences.
Experience depends very much where you are. Infantry is all about discipline. Cavalry and Navy has a lot (and I do mean a LOT) of traditions. Most branches and fields have a lot of baggage. Signal service is very different. Still, that was a long time ago and things might have changed.
>one of the last thing i remember my father telling me was to never join and be a slave to the government.
A lot of military thinking is about following orders unless you are at a sufficient high level - or in a weird group.
>i had no clue what he was talking about at the time. he was a marine in vietnam, died from cancer years ago.regardless, i still wish i joined
Vietnam was all around a bad experience. It is however a credit to the US that there has been a lot of introspection over what happened. Most countries would have covered up things like My Lai.

You might want to look up RMA - Revolution in Military Affairs. It relates to much of this, including the need to use tech rather than talk about it.
>im sure the book would be a good read. setting up in total darkness sounds like a real pain in the ass
Most military secrets are not about tech capabilities but to cover up major errors by higher officers. It would be really hard to tell the tales without bruising a lot of egos and thus have the whole lot classified. As an example there us a somewhat suppressed story about a mock execution near the Soviet border in full view of KGB during the cold war. Great (but rather long) tale but a lot of people will insist very loudly it never happened.

Oh, I just remembered one fun story I experienced, I'll post it later today.

>>1356616
Can you even tell the difference between phases when they're in each ear? I've had a fair bit of experience messing about with 3.5mm sockets and can definitely navigate my way around mono and stereo. In fact I bought some of those TRRS jacks to mess about with add-ons to my smartphone; you can pull 1mA or so out of their active mic-circuit.

Also I learnt impedance matching in class a few weeks ago, so if it doesn't mean stupidly sized inductors I may attempt to make a π-network that lets my crystal radio function with my normal earphones. Or would a transformer be a better way to go?

>>1356637
>Can you even tell..
Many people claim not to notice the missing center. There's a simple experiment to test this auditory ability that has nothing to do with mono or stereo. Or just ignore it. Impedance matching is best done with a (small) audio transformer, the kind you use to transform the output of a tube to the speaker.

>>1356307
>wish i could build a giant discone for HF
pic from http://www.navy-radio.com/ant-shore.htm

http://www.5b4wn.com/main/map.php

>>1356758
>Lambert equi-areal projection
Nice.

>>1356628
Time for a story.

We knew Morse of course but most of the day to day traffic was by voice. There were however times when voice was not possible and Morse was the only way to get through. That happened on a day on a major exercise where a neighbouring platoon leadership felt this was a beautiful day ... for adding gas attack moment to the exercise!

I have no idea how much CS gas they had but man, it was vile. It was like the stereotypical London fog last seen by Sherlock Holmes seeping in like grey mist but on steroids. We on the station had nothing to do with the brisk gassing and wanted even less to do with it. Procedure called for alerting HQ and we kind of were caught in the moment and it fell on me to report in.

And I had a problem. I could cough and puke into the microphone as the gas increased beyond belief or I could go for plan B. I never liked the gas mask (an equally weird story for a later time perhaps) but that button labelled CW never looked better. So I put on the gas mask, cleared the head (and sinuses), turned to CW and reached for the straight key. And the message was duly sent according to all rules and regulations.

So I waited for the QSL. And I got it. With an order. "Put on gas mask." Puking into the microphone is bad. But guffawing hysterically inside a gas mask is a lot worse.

>>1356791
>equi-areal
Not really. Greenland is 2/3 of India, that's about the area that 'hangs' in the Indian Ocean between the Arabian Sea and the Bay of Bengal. Easy to remember.

>>1356863
Oh yeah, antarctica is also too thick. What kind of nonconformist projection is that?

>>1356872
>centered on africa
wakandan projection desu

>>1356899
>americo-centrist
Go back to the Gall-Peters you son of a bitch.

>>1356758
Or use mate desktop.

>Click clock
>Pic related drops down

>>1356307
>i put up a 270 foot dipole fed with ladder line, cant hear a fucking thing out of it.
That is really strange. A plain crystal set should have given you plenty of signals, especially at night. With that length you would get 160 m signals so we are talking about LF band. In summer that band would be noisy and you would hear plenty of lightening crashes.

>>1355521

Fuck paddles.

Real men use STRAIGHT keys.

>>1357372
I like straight keys; it lets you recognise people in a way a paddle cannot. It is strange how the tiny, tiny differences become so noticeable. is there a program to do stylometric analysis on Morse code?

>>1355280
I'm not into HAM, but I thought I'd chime in as I do something somewhat related

> Be me
> Marine electronics technician by trade
> Have loads of spares both at work and at home
> Did the GOC exam because of said job
> Needed to do some testing
> Cobbled together an MF/HF transmitter at home from old parts that we can't sell as new
> Ended up with a 500W MF/HF radio
> "Fuckit, might as well go all the way"
> Already have a callsign and MMSI number due to other projects
> When in my home office I fire it up just to see what's on 2MHz to 20MHz
> Now working on programatically decoding DSC to see which ships are calling which.

>>1357453
Why do you cite yourself? Can you not just talk?

>>1357476
shitty /adv/-habit.
Not proud of it.

>>1357476
back to your stamp collection, newfag

>>1357485
Ok, understood.
I'm interested in compact broadband antennas and I guess they may be used on ships. Do you use something like that?

>>1357499
Addition: Found this image on the front page of http://biara.org.. Do you recognise these antenna types?

>>1357513
>>1356708

>>1357273
yeah, a bit annoyed, to me awhile to put it up.
might just try hooking coax up to it

>>1357513
More here:

http://www.virhistory.com/navy/ant-ship.htm

>>1355453
Well turns out my calculations were just that wrong. Evidently I used an online calculator instead of properly doing the magnetic field path integral. Actually it would probably be a surface integral, but that's besides the point. I've started winding a coil antenna (have to snip the enamel wire every now and then to measure, so it will have a few solder joints and heatshrink in it) but with only 14 turns around a 9"x12" box I'm already 180µH. So I'll probably go for 32 turns with a tap at 16 to get about 411µF. Loop antennae are cool.

>>1357655
>that 411 is meant to be H not F
Well I decided to do two lots of 14 turns, as 360µH is within my 340µH to 5.3µH range with this capacitor (MW here is approximately 515kHz to 1,630kHz, though with tolerances added.) and this keeps me from adding another solder joint. Turned out I had exactly enough wire for 14 turns and 5cm of wire on each termination ±1cm, which is strange because I planned nothing and actually intended to stop and check at 15 turns instead of 14.

Aand it's 720µH. I guess L doesn't scale linearly with N, which might be the reason behind my past false calculation. If this is due to the wire being close to itself, I take it this is the reason why many MW loops are well spaced? I'll run it anyway though, see what I hear.

>>1357679
Nothing. I'll try again tomorrow with a transistor amp before the detector, that is assuming that my OPA2134-based headphone amp doesn't work at 500-1500kHz.

But I'm guessing stray capacitance here is the problem, what with all these wires next to one another.

>>1357585
Thanks. I found
http://www.navy-radio.com/ant-shore.htm
http://www.navy-radio.com/ant-ship.htm
which seems to be another version of the same.

>>1357499
>marine
For aerial signals we rarely use antennae smaller than 1.5m stick, so I wouldn't call them compact. back when I was working with trains, we used a lot of antennas that we just called SharkFin because of its looks. It was very streamlined and compact, and made for 3G communications.

The Southern Connection. Both GM0HCO/MM and DP0GVN have a website + webcam, but DJ0HO/MM seems to sail under the radar, no further info about the vessel.

yo, can i use this shit to broadcast radio??? https://www.novikneo.com/product_detail.php?idp=33&idpc=8&idpcs=

does anyone know?

>>1357842
only VLF sound pressure wave broadcasting, given the right transducers.

>>1357853
so no fm?
gonna buy a fm transmitter then
ty anon

Greetings, HAM-beasts. I was inspired by >>1357453 and placed an order for an RLTSDR yesterday in the hopes that i can use it for DSC reception. If not, i can probably do something else fun with it. I've started planning my setup around that and a dipole antenna. My question then is, do i need a balun if i only plan on receiving? If i need one, can i make one ? I have fairly extensive experience in electronics, but not much when it comes to RF. Can i solder one together from the bits and pieces i have around the house?

>>1357679
>L doesn't scale linearly with N
True, it scales squarely. A good calculator is
http://electronbunker.ca/eb/InductanceCalcRc.html

>>1357880
i would think you would need to decode them?
i dont think the cheap SDRs do well with HF.
>>1357585
>>1357513
>>1357764
would a discage/ discone cage antenna work well for broadband HF listening?

>>1357918
on land?

>>1357918
A length of wire and a preselector are enough. It is much more important to get out of the digital fog.

>>1357888
Many thanks, that's exactly what I need!

>>1357719
Well it looks like my total capacitance is on the order of 500pF to 5nF, possibly more, which would explain why I'm not tuning into anything.

>>1358039
What's the L of your 14 turn boxtenna?

Random question related. Is it possible to emit a radio frequency and control its broadcasting radius?

Ideally around 10-12 ft

End game goal is to build a robot who follows me. However he follows me through sensors and radio waves.

>>1358075
you can adjust transmit power, but walls and the things inside them will make direction finding somewhat less than reliable

>>1358077
Mind you im going into this with minimal radio knowledge. However i plan on using 6 or so receivers and just have it move in a towards the signal. When all recievers are triggered i want it to stop.

Im essintialy having 2 receivers on each corner so i guess a total of 8. That way if only the 2 on the front left corner are activated then it will go in that direction. If only the left side is activated then it will turn 90° and drive straight. This will most likely be used in an outdoor enviroment so bounce wouldnt be my biggest fear.

>>1355280
WOAH, I never come on DIY, I didn't know there were 4chan amateurs!

Hello! I am an extra class ham from the midwest. Looking forward to following these threads.

>>1358105
>what is K6MWT
-.- . -.-

>>1358108
>t.extra from 8-land

>>1358105
Ive never been on diy, im sad to say that im a noob.

Im going to college for mechatronics though, so im not completely useless. However what i want to do with my projects does not correlate with schooling so i have no idea half of the time.

>>1358123
>im not completely useless
The only people who are, are those who try to answer shit they know nothing about without at least googling to see if they're in the ballpark of a right answer.

Don't do that.

Welcome aboard.

>>1357880
First of all, no, a balun is not necessary if you're only receiving. The term balun comes from BALanced-to-UNbalanced, where a dipole antenna is balanced, and so is ladder-line, and regular coaxial feedline is unbalanced.

It comes down to reflected power and resonance-- that transition from balanced to unbalanced means there will be some impedance change between the characteristic impedance of the coaxial feedline and the impedance of the antenna where it meets the feedline, which results in reflections of energy in the system. When you're only receiving, that impedance mismatch still exists, and the received signal still is bouncing around, but it's so negligible when you think about the tiny amount of energy coming in. Though, theoretically, you should find that if all other things are held constant, a balanced antenna system will outperform an unbalanced antenna system that is otherwise identical.

What this ultimately means is that without a balun, your antenna is resonant at a different frequency than the formula says it will resonate at. If you're making a dipole and feeding it with coax, it'd be proper to put a balun in. But practically speaking, as you're just getting going, I really recommend that you just take whatever speaker wire you can find and run two wires out, connect one to shield and one to the conductor, and go from there. I suspect it will outperform the dipole you make and it will be way less work. After you play around with it, make the dipole antenna with a simple choke balun made from simply making some inductance out of a few windings of whatever coax you're feeding the antenna with, 7 or 8 turns, 3" diameter,

So, if balancing doesn't really matter when you're receiving, why does it matter when you transmit? Because the amount of energy at the antenna port is significantly higher than it ever is during reception. So a reflection will come back, and maybe add with itself, and that comes back into an antenna port, thats no good

>>1358110
Nice to meet you guys! I'm a 9, Wisconsin in particular.

I'll post rig pics tomorrow.

>>1358069
720µH.

>>1358139
Wait that's the 28-turn. The seperate 14-turn was 180µH.

>>1358137
>I'm a 9
If you move to MN, would that make you a 0?

>>1358128
Once in a while 4chan shows its good side. This post, and the autist with the bullet hole in his favourite bucket a while back, is the reason why i love /diy/

Thank you for an informative post.

>>1358303
Not him but there are a few comfy places here. This is one of the best, definitely, and >>>/g/cyb is pretty good too.

>>1358164
yup, which is just one of many reasons why you should never move to Minnesota.

>>1358303
hey man, thanks!

>>1358318
you forgot /pol/
and /k/

>>1358318
What's cyb?

>>1358668
/cyber/

>>1358689
Well it doesn't seem to exist at the moment.

What are some good vintages of the ARRL antenna book to look out for? I want the hardcover but didn't get it when I got licensed a few years back and now it's out of print, so I figure I'll just get a older one, not like there's much change over the years.

>>1358668
It is an occational general on Cyberpunk and security.

>>1358871
IPv7 never.

What is a good budget aerial for the baofeng uv5-re? I would like to improve my range, 1 for car mount and 1 for when its handheld at work.

Cheers.

>>1358884
Which band do you use?

>>1358884
Car is easy because the roof acts as a ground plane. Anything cheap on the roof will outdo the rubber ducky in the cabin. $20 mag mounts available, will do nicely. I recommend a cheap NMO trunk mount and a decent NMO dual band antenna.

At work in the office is tougher unless you're willing to run a lot of coax or deal with a large antenna right on your desk. I don't have anything I'd recommend for that setting.

>>1358884
you can find ones online for $2-$6. ive tested a bunch of them, and they all seem cut for around 150mhz.
also a tiger tail might help you if youre on the edges of a repeaters reach

>>1358875
What did anon mean by this?

>>1355381
>///M logo.

Mein neger.

Bump

>>1358994
Well since there will likely never be a need to replace IPv6, and that a particular cyberpunk fiction has a plot that hinges on it.

>>1359384
I never knew of a cyb story that ever went into protocol details.

>>1359453
Serial Experiments Lain, a 1998 anime. It features an imagination of what the future of the internet would look like from 98, and features the barrier between this "wired" and the real world being not so concrete as it is today.

>>1359456
Lain moves the plot all over the place, including Schumann resonance.

some porn from that chan that is twice this chan /hamradio/

>>1357513
>>1357918

>>1359604

>>1359604
i bought one from diamond, it was my first antenna. works alright, i just wanted to build a giant one for HF and shortwave listening. but if a dipole will work better, i wont bother i guess.

>>1356053
why the fuck would you use a DOT to indicate it when there's only one dot per country. You could color the whole country and it would be a far more useful map

>>1359603
>Russia
That's pretty impressive if it works.

>>1355280
All of you virgin faggots playing with walkie talkies. Be a chad like me and get a discord server.

Who /DMR/ here?

>>1359959
>discord
>chad
>posts a little kid that was molested by jews
upvoted

>>1357842
Appears to be class D given the size.

I was going to say use it to drive a modulation transformer but class D amps are a bit unreliable with some odd loads.

>>1358900
Just set up as a basic 80ch uhf radio.

>>1358969
I'll check out the roof mounts

I should have been more specific for work description, I work outside in field maintenance so short distances but i do enjoy running dual channel mode so i can listen in on highway at the same time

>>1358970 I did see about tiger tails, makes sense, for that price range i might do the same.
Cheers.

>>1360021
>a bit unreliable with some odd loads.
Yep things could get south with inductive loads.

>>1360059
>80ch uhf radio

For those who have no idea this is UHF CB.
https://en.wikipedia.org/wiki/UHF_CB

If its for local work use just get a plug and cut your self a 1/4 wave and wack some heatshrink over it.

>Change of topic
https://youtube.com/watch?v=kqvWT8GaxMY

>>1360059
tiger tails may help or may not, i go hiking a lot and its gotten me into repeater while my other radio( same setup but without the tail) was hardly readable
>>1360197
UHF CB doesnt seem that fun.
i guess it has its uses though.
at least on 27mhz you can get some skips, hearing that is what made me want to get my ham licenses
i think the most power you can use is 12watts.
if i modded my radio i could put out 100w on there.... but i guess theres a reason they call it the "childrens band"
but, its part of the reason i got interested in ham

>>1360471
Rat tails provide an increase in the communications effectiveness of most hand held vhf-uhf-cb radios. It does this by providing a larger counterpoise. Some certain cheap chinese brands of radios may have their front ends overloaded by doing this.

>>1360477
For said radios there's the pig tail option.

>>1360563
>>1360477
same things right?
mine just kinda hangs down

>>1360898
>mine just kinda hangs down
me too...

>>1360949
left or right?

>>1360954
left

1941

>>1360563

I have a 6 meter handheld where the speaker mic's cord makes for a good counterpoise.

>>1360471
Eh, the UV-B5 doesn't need it on UHF anyways.

There is a metal plate behind the battery.

>>1360007

DMR sounds like crap.

It seems most DMR users are just appliance operators who talk through their dingle dangle dongle.

>>1362138
>good counterpoise
especially when uncoiled..
Which radio is it?

>>1362143
this. call me when any digital jew open-sources their codec and implementation

>>1362534
oath, I'm kinda interested in FreeDV but all this AMBE-based bullshit can fuck off until the patent on it expires

I keep daydreaming about building a handheld (or close to it) 2m/70cm sdr transceiver based on a limesdr mini and one of those turdberry pi clones, just to mess with non-FM modes. Not sure if those little arm boards are powerful enough but aside from that it looks like all the pieces of the puzzle are readily available and not super expensive.

>>1362640
>all the pieces of the puzzle are readily available
Including the 2m/70cm amp/filter that makes a watt without flooding your environment with digital crap? See >>1357936, it's getting worse.

>>1362640
they're powerful enough to run the baseband radios in cell phones, so why not

>>1362673
maybe we'd just better all go into the digital fog and start using modes that can be recovered under the noise

>>1362640
>Not sure if those little arm boards are powerful enough
Seems it is. From https://www.rtl-sdr.com/going-portable-with-the-airspy-hf-rapsberry-pi-and-7-inch-touch-lcd/
>My first tests showed that the Raspberry Pi works very well as a Spyserver: the CPU usage stays below 40% and the power consumption is low enough to allow it to run for several hours on a regular USB power bank. If I add a 4G internet connection there I could leave the Spyserver running and connect to it remotely from home.

>Then I wondered if the Raspberry Pi would be powerful enough to run a SDR client app. All I needed was a portable screen so I bought the official 7” touchscreen for the RPi.

Also https://www.rtl-sdr.com/wireless-lan-professionals-podcast-what-is-hackrf-portapack-and-havoc/

>>1362676
>start using modes that can be recovered under the noise
>not already doing everything with CW

>>1362779
adafruit have a project especially for that, though it uses their 3.5" TFT touch screen and their own software. Add a power bank and you've got a portable radio, if you want. I could never get the TFT working properly, perhaps because I was trying to use their cheaper 2.8" TFT instead.

>>1363124
the adafruit thing was what originally started me down this path, thinking that if a shitty receiver/spectrum display was so easy then what could be done with a bit more work (and how much more compact could it be if making it small took priority)

even if I couldn't build something handheld-sized, a slightly bigger form would be fine too as a portable rig to piss about with from mountain tops or later to use as part of a microwave system (limesdr claims to handle up to 3.8ghz natively and then transverters could put it to work on the higher bands once I upgrade my licence)

>>1362779
neat, i've seen the hackrf thing and another one that was similarly small but had a corner sliced off for a cw key (can't remember its name or any details though)

>>1363124
out, steampunk, out

>>1363175
What are you implying? That CW is a relic of centuries past? Or that a ribbon-cable-covered hacked-together portable all-band radio lends itself to a certain aesthetic?

>>1363165
>once I upgrade my licence
I don't think you need to upgrade. Novice and Advanced no longer exist, only Technician, General and Extra [Wikipedia].

* Amateur operation at 76-77 GHz has been suspended till the FCC can determine that interference will not be caused to vehicle radar systems.

>>1363344
I heard if you're Canadian you can't homebrew without an Advanced license

>>1363345
Interesting. I was only looking for the latest FCC rules. Does that mean you can't even diy your own antenna? Sounds like a consumer license to me..

>>1363344
I'm Standard class in VK so I'm still limited to the main HF/VHF/UHF bands, nothing below 3.5mhz or above 5.8ghz

http://www.wia.org.au/licenses/standard/about/

Need to do some refresher study (been a few years) and then take the upgrade exam to step up to advanced for more band access (and more power if I want it)

>>1363165
>similarly small but had a corner sliced off for a cw key
Could it be this one? https://hackaday.io/project/1538-portablesdr

>>1363436
yeah, i think that was the one

>>1363349
You can build your own antenna, only the home-brew transmitter is limited to kits. Footnote 2 in the text has an error, it should read "home-made" in the context..., not "build". Canada seems to have four certificates: B, B and 5, B/H and B&A. So if you have a 'B and 5' you can legally assemble a pixie kit, connect a piece of wire plus a key and cw around the world on 7023 kHz..

>>1363439
The QCX also has a key on board.

Earlier we were discussing replacing the crystal in a pixie or Frog Sound QRP transceiver with a more flexible source. Someone else has been thinking along the same lines:
https://hackaday.io/project/8903-qrp-pixie-dds-mod

Perhaps using a (low end?) smart phone for control, waterfall and audio could keep the cost down too.

>>1364301
an STM32F4 and cheap color LCD should be more than enough. see also mcHF

How much more efficient is CW than SSB? I commonly hear that CW has a 12-13 dB gain over SSB due to its smaller transmit bandwidth. However I have noted that when flipping between the 2.4 KHz filter and 500 Hz filter on various web SDRs when tuned to various frequencies no one is transmitting on, it shows a ~6 dB or so difference in the noise level. Would that lower background noise level from the narrower filter not be added to the 12-13 dB gain CW already has?

>>1364509
The bandwidth-related gain of 10log(2400/500) is probably included in that 12dB figure. The real advantage in terms of readability is way larger because the effective bandwidth of the adaptive human decoder is much smaller and the required (S+N)/N ratio can even be below 1 (or negative when expressed in dB).

>>1364509
In heavy QRM SSB gets you nowhere. In military grade QRM CW will get you there. I write from experience.

>>1364303
mcHF has been mentioned and it suffers from a few excessively expensive parts. That is why I was thinking of reusing a smart phone.

One interesting STM32F4 project is here:
http://www.sdradio.eu/weaksignals/armradio/index.html

>>1364301
>replacing the crystal in a pixie or Frog Sound QRP transceiver
Pixie yes, Frog et al no. Schematic shows why.

>>1364695
the mcHF was mentioned by way of design example. the display ($however much you're willing to pay) and the SoC (~$4 chink, $12 legit) are relatively expensive, but for replacing the VFO in a *single-band* radio, you don't need the relays to switch band-pass filters in and out (you could use daughterboards in some sort of slim "cartridge" enclosure), the Si5351 is cheap ($1.12 legit) and there are cheaper chink rotary encoders with better resolution than the boutique VFO tuning encoder they used, probably mostly because it was PC-mountable.
>smart phone
good audio, MAYBE, but limited/hacky I/O. would give points for someone having done it but would probably not use as daily driver

>>1364509
Here's a study that was in QST that covers everything from average transmitter power to required signal strength for the user to understand what's being said that puts the difference between SSB and CW at 17.2 decibels:
http://www.qsl.net/k4fk/presentations/Mode-sensitivity-2013-Dec-QST-Siwiak-Pontius-1.pdf

I do question their methods related to how they measured average radiated power though, as I would think CW not using any power between dits and dahs would make it easier to decode the signal than their measured 50% average power to transmit binary 0 with PSK31. Differentiating 100% power from 0% power seems like it would be easier to do with a weak signal than differentiating 100% power from 50% power.

>>1364823
For getting started on the cheap and cheerful, which of the two do you recommend?

>>1365439
Not in the same league at all but ubitx. You could get some serious use out of that.

>>1365439
The cheapest Pixie is €2.50 delivered, the Frog about €10. Technically, the Frog is better. There are different versions of both, scan alibay to have a look.

If this is your very first 40m CW adventure, I would get a Pixie-S that has a built in key tone beeper, a usable RIT (no screwdriver required) and comes with a nice enclosure.

>>1365453
This is the Pixie schematic for comparison. It's from the user manual http://www.lxqqfy.com/files/S-Pixie.pdf which contains a number of pixie versions and also something about suitable antennas. Some errors in it.

>>1365450
That's what comes after the pixie-type radios when you know this is will be your hobby. Very interesting (semi-traditional) concept, really well documented and amazingly cheap for what you get. http://www.hfsignals.com/

Hey anons, nice to find a place to talk about radios. I got pic related in my dad's house, is there anything interesting to do w it?

>>1365913
Oh, 1962. I found the manual. It's a Heathkit GW-10, either A or D. It has tubes and the 10D version also has a real mechanical chopper to run it from a 12V/6V battery. Connect a few yards of wire, power it up, switch to variable and scan the band..

>>1365961
It has a kind of RCA input for the antenna, what cable should I buy? Coaxial? Or other type?

>>1365984
None, just connect a length of wire and test.

>>1365961
>10D
add 1 GBP for hot dipping sauce

>>1365994
Dumb question,The length of the wire is related to rx/tx power of the radio? If so, how many wire do I use?
Testing atm

>>1366172
5.5m should get you started.

>>1366174
Nice, thanks bro.

>>1366176
the length of the wire is related to the wavelength. the 27MHz CB band is 11m wavelength. divide by 2 to get a half-wavelength antenna. you'll probably want something better matched once you've checked for basic functionality. there are thousands of resources around the web on antenna design and more than a few for CB specifically, choose the one that works best for your situation
cheers

>>1356060
>mummy
spooky

>>1358884
Are Baofeng's the best bag-for-the-buck entry radio?

>>1366210
for VHF/UHF FM, they're okay. some DMR repeaters have banned Baofeng digitals because they hog both time slots

>>1366210
"Entry radio" is a really broad description, it depends on what role you're looking to fill. For just listening, an RTL-SDR would have them beat as they cover a much larger range of frequencies and can use pretty much any mode (including digital modes such as P25 and DMR, and can even do trunking as well IIRC) rather than just analog FM. For vehicle to vehicle use, a CB radio would likely be a better choice since Baofengs can encounter issues with front end overload when hooked up to a larger mobile antenna.

>>1366214
Baofengs can't even do DMR.

>>1366216
so Pic related is vaporware, then?

If I've got this right, electrically small loops (r << wavelength) are inductive, so are electrically large loops (r >> wavelength) capacitive? Are monopoles and dipoles the opposite (capacitive when too small and inductive when too large)?

>>1366271
Not all loops have a radius, it's the perimeter that sets the (fundamental) resonant wavelength. If the wire is too long, the loop is inductive and too short makes it capacitive in relation to the intended resonance. Same for a dipole. Electrically, there is no monopole, that's only the appearance. Every generator and every load has two terminals.

>>1366219
>vaporware, then?
Maybe not. Baofeng is merely a label used by many. DM-5R, RD-5R, more to come. If you look at baofengtech.com/purchase you will not find a single DMR radio and neither will you find the UV-5R because it was discontinued in 2014. Now any toy shop sells it.

>>1364509
>Would that lower background noise level from the narrower filter not be added to the 12-13 dB gain CW already has?
That would already be included. When you reduce your receive bandwidth by a factor of 4.8 when going from the 2.4 KHz filter to the 500 Hz filter, you also reduce the power your receiver is receiving from background noise by 4.8 times or about 6.8 decibels assuming the background noise is perfect white noise.

The commonly claimed 12 dB/2 S point difference for CW vs SSB probably comes from something along the lines of the gain from the increase in signal to noise ratio when going from a 2.4 KHz SSB filter to a 500 Hz CW filter plus the additional gain due to CW transmitting at 100% power while SSB doesn't. The commonly claimed 12 dB/2 S point difference likely does not include any gain you see from ease of understanding morse code at lower volumes vs voice as that would be harder to quantify.

>>1366784
The occupied bandwith of a slow transmission signal is much smaller than that of conventional filters. 25WPM CW uses about 50Hz, WSPR about 7Hz and JT65 about 178Hz. If you look at the WSPR database you find a typical minimum SNR of -33dB for a successful transmission which takes almost 2 minutes. WSPR is a beacon mode though, not a QSO mode.

In contrast to CW and SSB these specialized digital modes are not 'real-time', you have to prepare your message beforehand and the transmission start time is not free but is synchronized to UTC. Interestingly, the mode that comes closest to realtime full duplex (like a phone call) is QSK CW (or at least quartersecond semi-QSK). This allows you to interrupt the other side like in a normal conversation. Only ragchewers value that..

I have a simple question that probably has an obvious answer but I'll ask anyways. Since transmit power on SSB varies based on how loud you're talking, does power draw on transmitting with SSB also depend on how loud you're talking or is it the same no matter if you're talking or not?

>>1366916
>25WPM CW uses about 50Hz
That picture looked really bad. Is that splatter or a realistic figure?

>>1366943
think about how an amplifier works and it'll be obvious

>>1366949
Less would be technically possible, but that would make it difficult to copy.

>>1366949
Not splatter, it's in-band. CW has a variable symbol composition and produces sidebands (like AM). A five needs more bandwidth than a zero.
>>1366943
Yes, power draw follows output. Same as CW but unlike FM or FSK. Good SSB radios usually have some sort of audio AGC/limiter that regulates the average power no matter how loud you speak. If the AGC is too fast you can hear the operator breathing..

>>1366954
>>1366964
Interesting.

Unless I am mistaken (a distinct possibility) CW in itself has no bandwidth; it is only when modulated by dots and dashes this appears.

Idea A: If I have understood this correctly there would be a different bandwidth for dots and dashes where the dots bring forth 3x the bandwidth of dashes.

Idea B: If dots and dashes modulate the carrier, wouldn't that mean we effectively have sidebands above and below the carrier? The picture suggests symmetry, broadly.

Idea C: If we truly have symmetric sidebands, couldn't one set be filtered out while retaining the information?

>>1367059
>only when modulated
Yes.
>sidebands above and below the carrier
Yes.
>couldn't one set be filtered out?
I don't know.

The used bandwidth is mainly a function of code speed (25 WPM in the example, which is quite fast, about two characters per second). There is a slow CW mode called QRSS, but when a dit takes ten seconds and a dah half a minute it is better done by a machine. Humans do not hear the dits and dahs, they recognize a character by its rhythm like you recognize a spoken word without deconstruction to syllables or phonemes.

>>1366952
Derp. I should stop trying to think about things when I'm tired.

>>1367059
Here's an article I bookmarked a while back that covers this subject in more detail than one could fit in a post here:
https://www.w8ji.com/cw_bandwidth_described.htm

>>1367059
>) CW in itself has no bandwidth;
In real world carrier is modulated by noise (both phase noise and amplitude noise).
The shittier the radio the wider the bandwidth.
Thus taking cheap radio and adding a 2kW amplifier would be a disaster, as the noise will be amplified CW will produce quite strong side bands.

Can someone explain to me what a SSB waveform looks like?
I get how AM and FM work, but I've only ever seen SSB signals shown in bandwidth diagrams.

>>1367834
Does it just chop off the bottom half of the signal?

>>1367834
RF follows amplitude of AF, phase reversal at zero crossing of AF. Picture has a very low RF frequency to make that visible.

>>1367837
Well you can't transmit that, it isn't remotely sinusoidal. A normal AM signal is If*Rf, where both can be approximated as cosines. When multiplied in a mixer, the output has a "cos((w_1+w_2)t)" and a "cos((w_1-w_2)t)" part, meaning it has signals of frequencies on either side of w_1, plus a DC cos(w_1*t) term if that makes sense. I assume SSB takes only one of these. When looking at a fourier transform (like an SDR's waterfall) of an AM signal, you'll find that there are frequency parts varying to each side of the main carrier frequency, which correspond to the (w_1-w_2) and (w_1+w_2) sections. An SSB signal on the waterfall will just have a spread on one side of the carrier frequency.

>>1367850
I think he asked how the signal looks like in the time domain.

>>1367868
Shouldn't a (normal) AM signal look more like pic related? Using a diode detector on that will give you a full-bridge rectified output signal instead of a sinusoidal one.

>>1367868
>>1367871
Anyway, It shouldn't look very much different at all, here's what I got by messing about with graphs. Red is SSB, grey is DSB.

>>1367875
I must admit that surprised me a lot. I had expected something more.
Could you also show USB vs LSB?

>>1367883
Red is USB, blue is LSB. Note that I'm using cos(wt)*(cos(wf)+3) as my modulation function where f is the angular frequency of the audio signal. If you take out the +3 you get what looks like >>1367868 and removing one sideband just leaves you with a single constant wave signal. But I have no idea if ring mixers can handle a DC component in an input.

>>1367883
Look at the zero crossing of the envelope to tell SSB from AM, it looks different. There are two images that show that there's very little RF at the zero crossing of the modulating AF signal.
>>1367898
>ring mixers can handle DC
Sure, DC appears as carrier, what else.
>>1367806
>quite strong side bands
That's why we have dBc, no matter at which level.

>>1367948
>That's why we have dBc, no matter at which level.
dBc isn't enough w/o knowing carrier level, esp when you hook up your rig to your PA.

I was reading about the Shannon Hartley theorem, and was wondering what sort of systems it applies to? Surely a CW binary transmission has an infinitesimally small bandwidth? Is there something stopping me from transmitting one binary signal at 10,000Hz and another at 10,001Hz? Or is my assumption that you can "just take the fourier transform over a time T << Bitrate" wrong/ineffective to get rid of the beat frequencies? Makes you wonder how to get a nice live waterfall to begin with, but I'm guessing sample frequency S is a limiting factor, along with the S:Bitrate ratio.

>>1368067
>Surely a CW binary transmission has an infinitesimally small bandwidth?
It doesn't. See >>1366916.
>Is there something stopping me from transmitting one binary signal at 10,000Hz and another at 10,001Hz?
No, if you switch between the frequencies slowly enough.

I'm not familiar enough with the theorem to give you the formal definition, but it applies very broadly. You can also view your first example different way: CW is amplitude modulation and your dits represent your highest modulating frequency. Thus you get your two sidebands as usual and since the actual information is in those sidebands, you have to take their bandwidth into account.
Normal CW takes even more bandwidth than just 1/(2*dit_period), as that would be annoyingly soft keying.

>>1368161
>No, if you switch between the frequencies slowly enough
Well I meant two seperate signals, not one where a 0 is one frequency and 1 is the second, but thinking about it in terms of AM makes sense. The fourier transform of the transition between 0 and 1 will hardly be a single frequency line. I guess to decrease this spread you'd need to vary the amplitude slower, but by what function? Best I can find is tanh(x), thought it approaches 1 and 0 asymptotically. Looks like separating your CW transmissions by at least 3f is needed, where f is the modulation frequency for a square wave. I'm beginning to learn how much I have to learn.

>>1368010
>w/o knowing carrier level
It is always 0dBc. The kilowatts do not appear at a distant receiver, the signal does and its properties.
>>1368067
>>1368161
There's an article about optimal keying and envelope shaping:
http://fermi.la.asu.edu/w9cf/articles/click/index.html

>>1368194
>It is always 0dBc. The kilowatts do not appear at a distant receiver, the signal does and its properties.
absolute value is crucial
noise and sideband emissions get amplified and spoil the band
the higher the output power the cleaner the source must be

>>1368548
When you crank up the volume things get louder. Your neighbors will complain while others may not notice at all. Picture: Real world SSB in the frequency domain.

>>1355280
Anyone wanna help a really stupid guy wrap his mind around antennas?

I'm trying to build an improvised antenna. Just for receiving, not for sending, and mostly around 140-160MHz. I've been trying Google for hours but everything I find out just leaves more questions than answers.

What's with there being two wires or points of contact with the radio instead of just one? What are they for? I know it's not like electricity where there's positive and negative terminals, but what else is it? And why do a lot of antennas like the ones on FM radios you buy (whip antennas?) only seem to be one piece of metal if an antenna needs two separate pieces of metal?

I have a Baofeng that I'm trying to pick up local public services and other stuff with. I read that the antenna should be half the wavelength you're trying to pick up, so I looked up what that would be for about the middle of the range I'm trying to get (it was 37 inches), cut down a piece of copper pipe I had laying around, hose clamped it to a wire (I even sanded and cleaned the end of the pipe for a good connection), taped it vertically to a tall rail on my porch, and alligator clipped it to the center wire of the old antenna which I'd dissected. No dice. I know that channel should have been active, I was watching the local PD and ambulance which I'd confirmed the frequencies for with a borrowed scanner earlier. Is the problem that I didn't attach that second wire (in the stock antenna it was a spring wrapped around the center wire) to anything? If not, then what?

Pic related is how I attached the wire to the dissected antenna. The red arrow indicates the second point of contact I'm trying to understand the purpose of.

I'm not normally a dumbass, I just can't understand fucking antennas for some reason.

>>1368820
This picture is the copper pipe and the pole, at the other end of that wire. The pipe is roughly 37 inches, which should be half the wavelength of the frequency I'm trying to pick up.

>>1368820
The second one is ground plane ,I think, someone can correct me.

>>1368826
>second one is ground plane
What always works well is a quarter wave ground plane antenna, one radiator and four radials, 45° bent down. https://www.google.com/search?q=2m+band+ground+plane has a lot. You can hang it down from the ceiling if indoor.

>>1368820
You cannot end-feed a half wave antenna, total mismatch. The first improvisation is a quarter wave whip connected to the center conductor and a counterpoise of about the same length connected to the outer conductor. Scroll back or CTRL-F rat-tail.

>>1368957
>>1368993
Okay, I'll try the thing in the picture first. I have more scrap copper pipe.

What is end-feed? You mean where I connected the wire to the antenna--like would it work better if I had connected it to the middle?

Is a copper pipe like that a good material, or should I use something else?

And can anyone explain any better what the function of the center connector and the outer connector is? That's what's really confusing me.

>>1369177
https://en.wikipedia.org/wiki/J-pole_antenna

>>1369177
youre going to want to get some coax, and have an adapter on one end to fit whatever radio you might be using. most sold for radio purposes will have pl-259 connectors on them. a pl-259 will mate with an so-239, like here >>1368957
on HF, something youre not into,(yet) will be hooked up something like pic related
>Is a copper pipe like that a good material
yes, its great. wider the better.
i use a copper jpole like >>1369200 and i can reach repeaters 60 miles away, no problem.
your best bet is to run some coax and set up an external antenna. the ground plane is very simple, it was one of my first antennas. it worked pretty well. but the jpole i made worked a lot better. the ground plane can be made quickly, the jpole takes a bit more work, and is a lot bigger.

>>1369217
Okay, thanks for taking the time to dumb it down for me.

Why is it important that it is coax? Does just anything with electrical continuity on two separate lines work, or does it have to be coax? Like, mine is from speaker wire, does that work just as well?

And how are you supposed to know the pros and cons of different shapes of antenna? Like, I have a shitpile of that copper pipe so materials availability isn't really an obstacle. How do I know whether a dipole like your picture, or an antenna like >>1368957 , would work better for a given situation--and why? Is there any teaching resource that breaks it down in simple rules of flow from point A to point B like electricity, or is it just more complicated than that?

>>1369221
no problem m8, i still have trouble understanding a lot of this.
you can use pic related, called ladder line, but youll have to find a way to match it to your radio. the radio wants to see 50 ohms, or something close. cable tv coax is 75 ohms. the ladder line is 450 ohms.
>And how are you supposed to know the pros and cons of different shapes of antenna?
it get tough, especially at High Frequency, (1-30mhz) because the antenna can be as long (or longer) than a football field. with what youre trying to listen to is around the 2 meter ham band (144mhz) the antenna gets a lot smaller.
i wouldnt use the antenna in the picture i posted, its more for higher frequencies. i would read this http://hamuniverse.com/w4bwsmatching.html and see if that helps you out at all.
im sure someone could explain this better, im pretty new to this. but antennas were really frustrating when i started, so ill help anyway i can.
you could also buy something that is called a discone antenna, that works on many frequencies, but my jpole still out preforms that hands down.

also i guess i must bake new bread

>>1369244
>bread in the kitchen 1st rising right now
Mom? Is that you?

>>1367834
Those diagrams only tell part of the story. AM has two side bands and to understand SSB it helps to understand the role of side bands in AM.

Go to a websdr and tune up an AM broadcast station (pure AM not IBOC) and watch it for a wile. Note how side bands related to audio tones. If you can find one with some single tone audio sounds all the better.

If you have an AM or SSB CB and a local sdr covering that band you can make some sounds and look at them.

new bread for us ham fellas, very fresh
>>>9809826

>>>9809826

>>>9809826

>>9809788

well fuck me. if youre not as retarded as me, im sure you can find it

>>1369257
>>1369257
>>1369257
>>1369257

New thread

>>1369272
thank you. what was i doing wrong?
i tried to do it on another board, and it worked, confused why it didnt work here

>But we are still before bump limit

Oh well lets post it out.

>>1369276
Putting the wrong number it would seem.

>caption_this.jpg

>>1369240
Yeah. Thanks for the help. I really wish it could be broken down into simple rules. Like, you don't have to learn a specific design of wire to connect, say, a lightbulb to a battery, because you know the principle that you must connect a circuit of positive, negative, and load, of wire or other conductive substances, and it will work. You can build the system yourself because you know the underlying principles, and what will or won't work and why. I don't like just following arbitrary designs like "J pole" or "dipole" or whatever because I don't understand the underlying principles. I wish I could just learn the basic rules that determine how radio waves move through the air to your antenna to your radio, and build my antenna accordingly, but no one spells it out in plain terms. I assume there are just too many principles and complicating factors to make that practical.

My "way to match it to my radio" is that I dissected an old antenna so I have two bare metal contacts that I use with alligator clips to the speaker wire. That shouldn't cause any problems as long as it's a good metal to metal connection, right?

>>1369240
Oh and how does that work with ohms for a wire? How can one wire have more or less resistance than another wire, if they're all just copper? Doesn't copper have the same properties of conductivity no matter what rubber or plastic it's put in?

And I thought resistance was related to the distance--so a 50 foot wire would have more ohms of resistance than a 10 foot one for example. Is that not true? Do I need to cut my wire to length and measure with a multimeter to get it as close as possible to 50 ohms? Or is that not how this works at all?

Like I said... every answer I find about antennas just creates more questions...

>>1369292
>Doesn't copper have the same properties of conductivity no matter what rubber or plastic it's put in?

At DC yes but this is AC in the RF spectrum.

Fun question to ponder:
>How long is one wavelength at mains frequency?

>>1369300
huh ?

Again... each answer just leads to more questions. I'm beginning to feel downright retarded.

I did not know that a radio antenna had anything to do with AC. I didn't even know that the qualities governing conductivity and resistance were different from AC to DC, I had always assumed they were the same.

And I have no idea what you mean my mains frequency, all Google results are about electricity not radio.

>>1369308
>each answer just leads to more questions

Perfectly normal. Only teens "know everything".

>>1369316
I guess. I don't claim to know "everything" and I'm not even trying to, but I thought I had the basic idea of how copper wires conduct stuff down pretty well, only to find I didn't even know that

>>1369217
Shouldn't you be using a balanced signal for that? Feeding literally 0V to your second monopole is a bit silly looking, though I assume the image implies you put the anti-signal on the shield instead of using it as a ground. On this note, what is the optimal cable to use for a balanced antenna? Some sort of twin-core (twisted pair?) coaxial, or two operate coaxials?

>>1369308
Reactance is imaginary resistance, and is caused by capacitance and inductance, which all circuits have at least small amounts of. Capacitance is caused by two wires being near one another and allows a high enough frequency alternating current "pass through" the gap between the wires via the alternating electric fields between them. Capacitive reactance decreases with frequency and approaches infinite resistance at DC. Inductance is caused by the magnetic fields that generate around a wire with current flowing through it which resist the change in current. Inductive reactance increases with frequency and is 0Ω at DC.

Putting an alternating voltage source (like wall power) across a capacitor will allow some current to flow, but the current is not in-phase with the voltage, i.e. when the voltage passes through 0 the current is at its maximum. The result of this is sometimes energy is being pumped from the voltage source into the capacitor, and sometimes it is being pumped back into the grid, averaging to no power being dissipated in the capacitor. Inductors do the same. Provided you understand calculus, the formal definitions for ideal capacitors and inductors are quite intuitive. But in general, capacitance is maximised by having the greatest area and lowest distance between two conductors, while inductance is maximised by having concentric turns of wire such that the magnetic field of all the wire adds up.

But radio signals (and microwaves, light and X-rays) are an alternating electric and magnetic field, and hence can be emitted by alternating the voltage across an antenna.

>>1369403
Replied in new /HRG/