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is anyone really good with CocoaNEC or NEC2 and willing to show me their best tutorial on some random web1.0 [callsign].net? or should i buckle down and just use the standard docs?
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Mar 30, 2014 14:04
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| # ? May 12, 2024 19:39 |
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i'm so so tempted to buy one of these PRC-152 clones: http://www.jkarmy.com/eng/magento/triprc-152.html but i know that it will basically be a UV-5R in a big box, and the fact that it's sold to airsoft guys tells me it's probably all about the looks, and from what i've dug up it's not even actually compatible with the actual U-229 accessories like the H-250 since they couldn't even be bothered to modify the mic-amp for dynamic microphones, the TRI branded model has had all the internals replaced with a standard electret mic
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Mar 30, 2014 15:07
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longview posted:i'm so so tempted to buy one of these PRC-152 clones: http://www.jkarmy.com/eng/magento/triprc-152.html ahahaha, that's amazing never stop, china 
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Mar 30, 2014 15:46
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there's a video i saw where they use it to cut bricks one nice thing is it comes with a huge battery, but then so does the UV-5R at a third of the price (the extended battery for the UV-5R is actually nicely implemented and it will last for almost three 16 hour days at 1W UHF)
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Mar 30, 2014 16:10
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i have always, always wanted to get into milsurp but i have two reservations: --except for flagships like the R390A, performance seems to be sacrificed for ruggedness and simplicity --power supplies. no sorry i don't have +28V DC and -170V DC just on my bench here, what the gently caress you weird bastards
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Mar 30, 2014 16:37
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So I was poking around for simple homebrew circuits and came across this. I was wondering how the hell they were doing digital shortwave portables so cheap lately http://home.comcast.net/~phils_radio_designs/ http://home.comcast.net/~phils_radio_designs/Si4734_Hardware.pdf It's....actually pretty fuckin smart
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Mar 30, 2014 17:12
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modern mil stuff will probably run on 24V or even 12V if they put in a decent DC/DC brick, older stuff will run directly off the 28V bus and then you're hosed, sometimes it's +-28V too one radio i kind of want is the VX-1210: http://www.vertexstandard.com/ap/vx-1210.html SELCAL, 20W SSB on all HF bands, internal battery with long life for a HF rig, option for an internal antenna tuner that will tune a front-mounted whip for foot-mobile operation (sure hope that antenna's isolated though) and pretty waterproof as usual it's not designed for ham radio use so afaik it doesn't have a front panel VFO, instead you have to pre-program your channels and from what i'm told the dealer software isn't particularly easy to get either it would be hella fun to use in a field exercise though, but i think the IC-7200 is a better buy if i ever wanted to use it at home
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Mar 30, 2014 17:12
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Yeah i've seen teh 1210. Cool facts until last year, Motorola owned Yaesu Vertex, i was sad when we sold them off. I always thought that 1210 was one of the better HF mobile candidates i've seen, you can pull it out of the dash and take it in the woods when you get to the campsite. i've got a big obsession with HF portable and like to read the articles on hfpack. Some day I will buy an FT817. i wish the 703+ did 2 meters cause i'd buy one in a fuckin heartbeat
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Mar 30, 2014 17:25
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i've been looking at the FT-897 for the same reason but until they make a version with li-ion batteries i aint buying it i don't understand the reasoning behind using ni-mh in a new product, i tried using the ni-mh batteries in my T70E in the field this summer and saw reduced capacity even at 10 degrees C, switched to the china-brand li-ions and had no problems at all definitely wouldn't want to be on a field exercise in -10 or -20C with only ni-mh batteries in my radio, they just stop working, i still bring a ni-mh pack or two since they're easier to charge off 12V though
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Mar 30, 2014 17:46
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don't get those, get a kx3 instead
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Mar 30, 2014 17:59
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Got both the local 2m and 70cm repeaters programmed in (wihtout cable woo) and tested the 70cm one sends morse back with a signal strenght report and station id, kinda cool. other than break squelch very briefly i haven't really done anyhting because i don't actually have a license yet 
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Mar 30, 2014 22:34
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im'a do some test exams online now because the N-license (technician equiv) seems pretty easy.
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Mar 30, 2014 22:45
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ya just take the test but do the other test too if the reg one seems easy
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Mar 30, 2014 23:17
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6 meters is starting to intrigue me but i dont think there's enough population density here to warrant anything so many of my problems could be solved by a 706mkiig, argh "low band" reminds me of big flappy whips on the long fast cars of some angry highway patrol officers
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Mar 30, 2014 23:24
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i passed an online test exam so if i study a bit i could pass it easy
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Mar 30, 2014 23:43
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i wasnt up on the math when i took my extra so i literally planned on aceing every section except where you calculate the reactance of a 100 pf cap in series with a 20 uH inductor at 14.150 mhz, and it worked haha the extra exam is easy b/c all the frequency limits are super easy to remember. you get everything, specifically the bottom 25 kc of each band
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Mar 31, 2014 01:11
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Silent Key - Incalculable sadness and substantial humor in equal measure. Modern amateur radio recordings of varying length, presented without interruption or commentary. http://podbay.fm/show/730847090 compiled by the Jerkcity dude
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Mar 31, 2014 01:54
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hold onto your balls, i built a preamp decided to make it smaller and just fit a shrink tube around it when im done testing to keep water out, also gonna put some aluminium tape around the circuitry to shield it better added some loops to the semi rigid (  ) coax to trap water, this solution fits inside the mast for the discone, providing protection from direct weatherhaven't tested it on the spectroscope yet since i assembled it when i got home but disconnecting the bias current drops gain by about 20 dB so that's all good then, the bus-repeater is also coming in much stronger and i can run at around 10 dB gain vs. 30 it does look like local GSM traffic and TETRA can cause problems with intermod, but i think it's under control also, got my WSP80 soldering pen today, and it works! now i finally have a real soldering station
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Mar 31, 2014 15:46
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that looks great, love it! The dumpster got delivered today and is sitting on the driveway. It's on concrete all around and I realized that a: it's an enormous chunk of metal and b: it's insulated from the ground somewhat. i'm going to find a bolt hole and get a wire on it and hook it to the tuner, and attempt to make a QSO with a dumpster antenna. i figure with a counterpoise laid on the ground this thing should load up on at least 40 meters just fine. its 22x8x7 (l/w/h) feet
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Mar 31, 2014 16:30
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Jonny 290 posted:that looks great, love it! lol
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Mar 31, 2014 16:38
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jonny owns so much
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Mar 31, 2014 16:39
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i know a guy who used to do that with the railing next to motorways, he had to stop since people kept pulling over to help him with his car
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Mar 31, 2014 16:50
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i think my next project will be a 380/700/900 MHz band stop filter, holy poo poo these GSM and TETRA transmitters are strong 2-3 open coax stubs should do the trick, i don't care about the upper harmonics too much on the bright side, my 4G reception is fast as gently caress with three towers across the street pointed directly at me
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Mar 31, 2014 16:58
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i'm not sure where coax stubs stop and cavity filters start, theory wise. they both seem similar, but cavity filters have like the coupling loops and such? and are obv way higher Q.
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Mar 31, 2014 17:00
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a cavity filter would be way overkill, and i think they usually only reject a small band with a notch, so they're well suited to duplexers but won't work all that well for rejection something 100 MHz away, helical filters might be a good choice though i experimented with open stubs for a 23cm filter and found that they would reject 1/4 wave, 1/2 wave and full wave, but obviously 1/4 wave was the strongest rejection, so a 380 MHz 1/4 wave stub with cheap coax (to get the Q factor down) should get 700 MHz pretty well too for example this stopped working well above 1 GHz, probably since the unshielded injection point was getting close to the wavelength of the signal allowing it to just radiate over the filter
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Mar 31, 2014 17:05
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yeah, i'm not sayin cavs would be good here, just mentioning i've always wanted to experiment with creating 'better than coax' notch filters using some copper pipe and brass rod or something. not using the cavity filter coupling or w/e, just simple teed quarter waves
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Mar 31, 2014 17:08
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i also experimented with some inter digit filters by just putting two vertical wires above a small ground plane, was able to get about 2 dB insertion loss with a fairly broad-band response, winding the monopoles into little helixes and putting a grounded wire between them let me shape the response kind of hard to control what frequency is tuned but it was fun to look at the response, a broad helix gave a fairly steep response for example, and a long thin one gave a pretty broad response
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Mar 31, 2014 17:11
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just blew my first LNA, cutting quarter wave stubs live isn't the greatest idea, best guess is shorting at the far end of the coax caused either an overvoltage or undervoltage pulse to travel into the MMIC and destroy it, added a 1n4148 reverse protection diode (doesn't seem to have affected performance) i'll add that ESD diode on the output as well tomorrow, should help performance a bit also added my quarter wave stubs to the FM notch i already had, stubs for 395, 800 and 930 and I've got the strongest sources taken care of longview fucked around with this message at 19:14 on Mar 31, 2014 |
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Mar 31, 2014 18:55
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Ok gently caress it I just applied for the tech license exam. The next one after this is in september and also 2 hours from my location, while this one is may 23rd and half an hour from my location. I'm sure if I brush up on my L/C filter stuff and some regulatory bs i'll be fine.
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Mar 31, 2014 19:18
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dooo itttttttttttt
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Mar 31, 2014 19:22
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moving the filter box out to the antenna sorted the last of the intermod problems, i hadn't accounted for the ridiculous signal strength of those GSM towers so i had a pile of noise right in the air-band (800 and 900 MHz LTE/GSM mixing) as soon as i get the rest of the accessories i can seal it up and call it a project
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Mar 31, 2014 20:58
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spankmeister posted:idgi becuase you say i changed my mind because ethernet for a pair of dongles would be complicated + expensive
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Mar 31, 2014 21:19
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Mar 31, 2014 21:51
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yesterday I walked up on a mountain and found an FAA site Apparently it's a VORTAC (VHF Omnidirectional Range/Tactical Air Navigation System)transmitter. Those weird radio mushrooms are actually a phased array that rotates a radio beam around then 30 times a second. Older stations used to do it with a directional antenna that rotated mechanically, but that was dumb, so they don't anymore. Combining that with an omnidirectional beacon at the center of the array, an airplane can calculate its bearing in relation to the VOR station:  The TACAN part is a military version of VOR that also has direction measuring equipment, functions in the UHF range, and is more accurate because it uses two frequencies in the rotating beam instead of one. Civil pilots have access to the distance measuring function, so combining VOR and TACAN stations into one installation lets you get an accurate position from one station. more pics of the buildings attached to it:    what the hell kind of antenna is this? 
atomicthumbs fucked around with this message at 23:07 on Mar 31, 2014 |
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Mar 31, 2014 23:04
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i have no idea, those are cool as hell tho. nice photos
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Apr 1, 2014 04:35
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My baofeng keeps forgetting channel 0 after a few on-off cycles. Channel 1 seems unaffected for now so I'll see if channel 2 holds better but if I got a radio with Alzheimer's that loving sucks.
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Apr 1, 2014 07:56
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a few things learned: switch mode power supply for the DV hotspot was generating a bunch of noise even at VHF, this is visible as repetitive peaks spaced 62,5 kHz apart (switching freq for the psu), using a linear supply got rid of almost all the noise in this band how to build a good ESD/over/negative voltage clamp from discretes: use a BAV99 diode, which has about 2 pF of capacitance, less when reverse biased to 5V, connect the open cathode to a ground plane, connect the open anode to a zener diode, the BAV99 capacitance will be in series with the zener so a standard SOT-23 zener diode for 5.6V which has about 400 pF of reverse capacitance will only drop gain by about 3 dB and provides a good clamp for transient overvoltage conditions
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Apr 1, 2014 16:12
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speaking of diode capacitance, i was reading about varactors last night and such, and now am looking at direct conversion receiver projects its so simple! honestly though if i do a DC receiver i'm just going to strap one of those $5 DDS boards to an arduino and LCD/buttons i did find some neat designs for varactor tuned filters though and it got me pondering
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Apr 1, 2014 16:16
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if someone would design a tracking frontend-filter that tied into SDR# i would buy it in a heartbeat unfortunately i think it would be pretty expensive and complicated, most circuits just don't like being pulled or pushed that far
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Apr 1, 2014 16:35
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| # ? May 12, 2024 19:39 |
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couldn't you just use a big pile of bandpass filters and some relays
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Apr 1, 2014 17:20
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