fullsquare
@fullsquare@awful.systems
- Comment on More CUDA please 1 day ago:
real. every prediction i got from computational chemists was wrong
- Comment on NanoVNA vs. Loop antenna SWR testing [Question] 4 days ago:
I wouldn’t bother with air core. Ferrite beads allow you to use old calibration. If you make 1:1 balun just by threading coax through toroid, you can use old calibration as well provided it’s the same coax. Keep in mind minimum bending radius of coax. There are other designs, like using twisted pair on toroid
I’ve seen people using PE-Al-PE pipe for variables, this gives you layer of good dielectric (polyethylene) in dimensionally stable form. One connection is aluminum layer inside the pipe, and for the other you’ll have to figure it out on your own. Retuning might be required anyway within the band (magloops are narrowband) Common way to make variables is to bolt two of them in series, so that no sliding contact is used, moving part is the same for both. This is good for high voltages also but i’m not sure if you’ll need it
- Comment on NanoVNA vs. Loop antenna SWR testing [Question] 4 days ago:
Yeah this lower one looks better but still probably your capacitor value in loop is way off, try to find frequency where impedance is real (purely resistive; green line on smith chart crosses horizontal line in the middle) and work from there, then you’ll know whether to increase or decrease it. resonance is narrow so you might miss it. there’s a reason why magloops are made with variable capacitors (sometimes retuning is required due to changes in ex. humidity)
- Comment on NanoVNA vs. Loop antenna SWR testing [Question] 5 days ago:
i’ll add that in a way SWR chart is more resistant to misuse, because if nanovna is calibrated with wrong length of 50 ohm feedline, or without feedline at all, then smith chart will be rotated by angle depending on difference in length of that feedline, while SWR chart should look the same. for example, if real part of impedance at resonance is too low (ex. 20 ohm), and feedline is quarter wavelength different from what nanovna was calibrated with, then impedance will be still real but too high (ex. 125 ohm), while SWR chart should look the same (1:2.5 SWR minimum) (barring losses in feedline). (this works the same way as quarterwave long feedline impedance matching scheme). for different feedline length differences (non-multiple quarterwave) impedance will be complex at antenna resonance. this problem is avoided by calibrating nanovna with feedline
- Comment on NanoVNA vs. Loop antenna SWR testing [Question] 5 days ago:
idk how you have done that, maybe i have older version but for me this marker just reads CH0 SWR 1.00/(value)
you can pull up a smith chart, this will tell you whether impedance is too low or too high, since it’s still not matched at resonance
- Comment on NanoVNA vs. Loop antenna SWR testing [Question] 5 days ago:
you can get away with very inefficient antennas on HF reception, so i wouldn’t take SDR reading very seriously. (atmospheric noise dominates all noise, so amplification will get you useful signal with amplifier not introducing significant noise on its own. reverse is true on vhf, and especially on uhf and up)
resonance should happen no matter what power level. do you mean SWR 50 or 50 ohm? i’m not even sure if nanovna can measure SWR that high. it sounds like you have a short or open somewhere it shouldn’t be? you need to calibrate it after changing tested frequency range, have you done that? (calibration can be saved). at the vhf-ish frequencies, it would make sense that your loop becomes full wave or even larger. circular loop has impedance of some 100 ohms, but you have capacitor at the ends of it so it’s gonna be different
with magloops, with set size of loop, tune is via changing capacitance, match is via changing position (closer or further from loop, tilt away from plane of loop), shape or size (cross sectional area) of feed loop, you can match it exactly this way. coax stub can be lossy, if it’s just 4W then probably not a problem but with higher powers check if it’s not overheating
- Comment on Should I replace my laptop battery, and are third-party batteries safe? 2 weeks ago:
there’s nothing wrong with 3rd party batteries, if it’s worn down so badly that it no longer does the thing that it is supposed to then replace it, idk why it’s a question. I replaced mine when they’re at 60% of original capacity
- Comment on If the color of the Sun was orange, wouldn't the clouds and everything white also be orange? My friend is adamant that 30 years ago the "real" Sun was orange but got replaced with a white LED. 2 weeks ago:
Your best bet is to just not engage with them when topics like that come up
real soon it will include any topic
- Comment on If the color of the Sun was orange, wouldn't the clouds and everything white also be orange? My friend is adamant that 30 years ago the "real" Sun was orange but got replaced with a white LED. 2 weeks ago:
if sun was orange, it wouldn’t be orange, it would be just precieved as regular white light, and new-orange would be even more oranger than what we know today
- Comment on If a Space Elevator became a reality, wouldn't the cable act as a kind of wick for all of the unfiltered radiation from outside our atmosphere? 2 weeks ago:
you need really spicy photons for activation to happen
- Comment on Do people actually believe those "gurus" on the internet that supposedly "give advice"? These seems very sussy and feel scam-adjacent, isn't it? 4 weeks ago:
dude, people join irl face to face cults, of course they do
- Comment on [deleted] 1 month ago:
- Comment on Firefox dev clarifies that AI features will be 'opt-in' and there will be a 'killswitch' to disable them 1 month ago:
no no no no it’s on by default so it’s opt-out, and switch for that isn’t even implemented yet
- Comment on Industrial Strength Shitpost 1 month ago:
at least he didn’t say he “fell on it” and it was totally an accident
- Comment on YOLO 1 month ago:
it can be bought in italy as a cleaning agent without going through entire process as for reagents purchase iirc
- Comment on Could gunpowder be chemically addictive for humans ? 1 month ago:
apparently ww1 era british soldiers figured out that cordite works like amyl but shittier (more specifically, nitroglycerin part) pdfs.semanticscholar.org/…/009c8713aadd8accbb03b2…
- Comment on Could gunpowder be chemically addictive for humans ? 1 month ago:
smokeless powder is, sort of en.wikipedia.org/wiki/Nitroglycerin#Industrial_ex…
- Comment on How does the private equity bubble compare to the AI bubble if at all? 1 month ago:
Or you could use different hardware, maybe from competition, because result isn’t worth electricity it used
- Comment on How does the private equity bubble compare to the AI bubble if at all? 1 month ago:
gpus as used for genai aren’t really suitable for normal loads like aerodynamic simulations, genai uses low precision data like fp8, fp4, blackwells and such are optimized for it so hard that you can’t really do anything else on this thing
- Comment on Sandy Loam 1 month ago:
nah. loam is, for example, 40% sand, 20% clay, 60 silt and it’s close to middle of that polygon
for example, draw a line from 50% sand to 50% clay,
- Comment on qt π 2 months ago:
I meant weaker per kg of body weight
- Comment on qt π 2 months ago:
Square-cube law means that as they get bigger they need to hunt less (lower rate of heat loss per kg of birb) and get less powerful compared to their size
- Comment on Behold and despair! 2 months ago:
some common friend spilled the tea in advance perhaps
- Comment on Why are so many after-shave lotion perfumed ? 2 months ago:
Tax reasons perhaps? In some countries ethanol with (certain kinds of) perfume mix can be taxed as denatured alcohol, otherwise some other kind of denaturant would be needed
- Comment on same shit every day, on god 2 months ago:
for ccgt it’s more like 2/3 for gas turbine, 1/3 for steam turbine split, even more uneven for diesel/steam because diesel exhaust is much colder
- Comment on same shit every day, on god 2 months ago:
and fuel cells
- Comment on Insulin 2 months ago:
as a citizen of a country whose government (-owned company) makes insulin, this reads weird to me
- Comment on Insulin 2 months ago:
good. generic biosimilars cost like 1/5 of the on-patent thing price
- Comment on Insulin 2 months ago:
fyi this fella has no training in chemistry or medicine and is just some random ass programmer with severe case of “saving the world from my homelab” symdrome
- Comment on Insulin 2 months ago:
I don’t think it’s a thing because even the same insulin analogue from different manufacturer can have different dosing