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SperginMcBadposter posted:Nice chodetenna. What is it about thicker conductors that gives the antenna a wider bandwidth anyways? ask your mom
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Jul 29, 2015 21:27
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SperginMcBadposter posted:Nice chodetenna. What is it about thicker conductors that gives the antenna a wider bandwidth anyways?  I'm not exactly a physics major (though i could ask one of the physics experts at work some time), but based on my understanding of biconical/bowtie antennas it has something to do with the width of the element allowing multiple paths along the antenna, so the antenna sort of works because there's always the right length available but that's also a bit of a bullshit explanation, but i like this site for antenna theory: http://www.antenna-theory.com/antennas/wideband/bowtie.php e: also gonna add that it's as well built as it looks, the radials are hollow tubes but the core antenna seems to be made from fairly solid very nicely machined aluminium, there's two screws on the top and what looks like a lid but i'm not gonna open it in case there's one-time use gaskets inside longview fucked around with this message at 21:36 on Jul 29, 2015 |
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Jul 29, 2015 21:29
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something something skin effect
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Jul 29, 2015 21:40
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SperginMcBadposter posted:Welcome to rf where everything is loving magic
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Jul 29, 2015 21:47
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SperginMcBadposter posted:Welcome to rf where everything is loving magic black loving magic https://www.youtube.com/watch?v=rahzrPdEeE8
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Jul 29, 2015 22:00
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spankmeister posted:black loving magic i like how at a certain point somewhere between uhf and "use waveguides, idiot" you have to start being careful about how you bend your coax because if you curve it too sharply the signal will just understeer and fly off the side of the curve e: i also like how "soft-spoken british electrical engineer youtube video" is a wildly successful new genre atomicthumbs fucked around with this message at 02:51 on Jul 30, 2015 |
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Jul 30, 2015 02:49
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10 GHz is up in the waveguide part of the spectrum. Also that's getting up into the range where you have to start using special PCBs and poo poo with the sidnal traces in between ground layers, and no bare leads to components because your wavelengths are getting short enough that loving everything turns into a radiator.
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Jul 30, 2015 03:20
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atomicthumbs posted:
him channel owns he scours eBay for weird poo poo and does teardowns. His dayjob is designing the electronics and electricals for huge LED art installations and stuff.
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Jul 30, 2015 05:59
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bye jonny 
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Jul 30, 2015 15:34
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rip
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Jul 30, 2015 19:45
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jonny290 died??
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Jul 30, 2015 21:04
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don't worry, he only ragequit the forums, not life
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Jul 30, 2015 21:24
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This cheapo Astatic brand SWR meter is loving trash. Also I tuned the antenna down to 12 meter band, and got a <1.25 swr over the whole band since it's so narrow. Haven't made a single contact though since I got my license.
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Jul 31, 2015 00:17
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Goddamn nobody on 12 meters either. Do one of the legit brands make a 6m/2m/70cm rig? I could buy one of those or try to get down to 20 meters by stacking copper 17 feet high and hoping it doesn't fall over.
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Jul 31, 2015 02:42
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SperginMcBadposter posted:Goddamn nobody on 12 meters either. Do one of the legit brands make a 6m/2m/70cm rig? I could buy one of those or try to get down to 20 meters by stacking copper 17 feet high and hoping it doesn't fall over. yaesu Ft-8900 sounds like what you're asking for, it's FM only though otherwise you're looking at HF+50 rigs mostly or the high end HFs but those are pretty expensive
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Jul 31, 2015 16:06
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exciting news, i got the exciter in the mail from myself! did some quick testing on how to add LSB modulation, all the low frequency LOs are logic level so i just plugged a DDS board into the 1st converter SMB connector replacing the 20 kHz carrier with a 15.5 kHz carrier and tuning 5.5 kHz down i can get the correct carrier frequency and lower sideband out with the correct AF bandwidth. so two DDS boards seems to be the right way to go for a LSB option. just need to check that i can offset the first LO by that much without running into bandpass filters e: found another signal generator and hooked it up as the LO for the 1st converter, LSB works perfectly! decent audio from the first test against the IC-706 longview fucked around with this message at 19:22 on Jul 31, 2015 |
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Jul 31, 2015 19:06
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Got my antenna tuned down to 20 meters. Some of these people on the CW only section are ridiculously fast.
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Aug 2, 2015 21:52
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I still can't get anyone to reply to me on CW.
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Aug 3, 2015 01:17
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SperginMcBadposter posted:I still can't get anyone to reply to me on CW. wish you wouldn't reply on SA
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Aug 3, 2015 01:19
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Maybe I'm doing this poo poo wrong or something. I've been sending "CQ" a few times followed by my callsign and then waiting to see if anyone replies. The SWR is 1.5 and I even dug out my grundig receiver to verify that I'm actually radiating.
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Aug 3, 2015 02:35
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band selector in the exciter now works, i decided to mod the old one after looking it over - just required adding some ORing diodes and bridging a few digits on the decade switches and got the receiver in the mail, it doesn't like travelling, time base drifted by a huge amount compared to where i was before (not perfect but nowhere near as bad as this), but here's a pro tip for adjusting synthesized receivers when all you have is an antenna and a phone: tune a time station like 10 MHz or 9996 kHz, i used 15 MHz since i can hear my GPSDO output there through the air. tune 1 kHz off in SSB mode don't use a spectrum analyzer app, the frequency accuracy isn't good enough with real time FFT, instead use a signal generator app to generate a 1 kHz tone tune carefully, if the volumes are matched the frequencies will beat against each other in your ear, when the frequencies are perfectly matched the beat tone will approach zero just did that with my receiver and managed to get it within 4-5 Hz by ear (off by 100 Hz initially) without having to break out the frequency counter
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Aug 3, 2015 19:32
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 http://www.ebay.com/itm/RARE-KENWOOD-TH-7-DUAL-BAND-FLIP-FONE-OLD-OFFER-/161784524307?hash=item25ab1bee13  100mw on 2m and 70cm. japan only.
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Aug 4, 2015 21:17
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atomicthumbs posted:
oh hey, i've got a broken one on my shelf, RF section doesn't work at all gonna fix it one day
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Aug 5, 2015 15:26
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atomicthumbs posted:
im the aol button
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Aug 6, 2015 05:52
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took my test today, held at a small spare conference room at the hospital. i was, unexpectedly, not the youngest person there, but other than myself and that kid it was a room full of white haired, rapidly greying, or bald white dudes. Our testers were apparently with the fire department. they started off talking about how someone got shot while doing a home invasion today, and "unfortunately" he survived, because taxpayer money. at any rate, I and another guy were there to do both the tech and general. three other guys just did general. i passed both before the guy sitting next to me (who had been taking the test last session too, apparently failed) could finish his. so, good times. They did ask if we'd been practice testing on multiple sites... and they pushed the multiple thing several times... but hamstudy and that ARRL started book was all i bothered with and it was fine. yay me
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Aug 6, 2015 23:41
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not sure i understand the "multiple sites" thing it's a single question pool lol there's not any variance in the coverage of the questions becasue the questions are the same, documented, and finite
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Aug 6, 2015 23:48
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Sniep posted:not sure i understand the "multiple sites" thing yeah, i wondered about that too. only explanation i could come up with is that they know of someone that hosed up because they were studying on some backwoods barely-known site that hadn't updated questions last time around? there's probably a few like that. doesn't matter, gently caress them, got mine
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Aug 7, 2015 00:06
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It's crazy how there's all that spectrum up here on 10 meters and nobody uses it.
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Aug 7, 2015 02:41
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SperginMcBadposter posted:It's crazy how there's all that spectrum up here on 10 meters and nobody uses it. it's crazy how nobody uses the thing that doesn't work
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Aug 7, 2015 04:14
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new personal best: 1874 miles with JT65 only running 5W of power 
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Aug 12, 2015 03:39
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awesome. I will be ready to do jt-65 as soon as I figure out why my ptt to serial to USB isn't working. just haven't had time lately
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Aug 12, 2015 03:52
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im an rf engineer IRL
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Aug 12, 2015 05:46
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sports posted:im an rf engineer IRL Burn the witch
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Aug 12, 2015 08:50
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j/k though rf is black magic
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Aug 12, 2015 08:51
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sports posted:im an rf engineer IRL text me
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Aug 12, 2015 12:38
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ham fest tomorrow with jonny290 rear end crack of dawn just outfitted a backpack with some power to test radios with... lol  perfect fit
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Aug 16, 2015 01:51
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and now that i have it wired up like this, it'd be a pretty good mobile operating backpack for QRP or something. I mean, that's a decent amount of power there if you blow it 5-10 watts at a time. the backpack has these soft padded inside compartments too to stuff a radio in
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Aug 16, 2015 02:02
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ham fest results: i found a frequency counter which is what i was looking for the most and this classic guy to play with:  +a large watt/swr meter for 50-150mhz 20/200w +a coax crimper with two die sets for most all coax hex crimps good day for $135, which was a lil more than planned - $60 on the counter but they go for 80+ on ebay for this model, and it is perfect for what i need, so not bad
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Aug 16, 2015 19:35
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That reminded me that we were having the annual one here sometime this month. Just checked and it was 3 days ago. gently caress 
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Aug 16, 2015 19:39
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SperginMcBadposter posted:That reminded me that we were having the annual one here sometime this month. that sucks lol jonny290 and i got to this one 10 minutes before the doors opened and rushed the joint for the first ~1hr it was open, he got a fistful of radios and a swr meter too, but really, there wasnt a whole lot of goodies at this one today here.
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Aug 16, 2015 20:19
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