Archive for category Technology

Headless Raspberry Pi B+ via Ethernet – from zero to success

R.Pi B+ BoadSo (somewhat late to the party, but anyway), I came up with a project I could use a Raspberry Pi for. Off to Amazon I went, and purchased this starter package, which I highly recommend. Everything you need, all in one place. I’m assuming you either bought this kit, or have the things you need, which I will call out.

To start, you will require the Pi B+, a storage card with NOOBS on it, a power supply, a wired USB keyboard, a wired USB mouse, an ethernet cable, a free port on your network router or network switch, an HDMI cable and an HDMI capable monitor.

No, there’s no other way. You need the monitor, keyboard and mouse. Sorry. not my fault. Everything I listed except the network cable, keyboard, monitor and mouse is supplied in the kit I linked to just above. As well as a lot of other really cool stuff. Hint. Hint.
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Review: E-Flite Blade 350 QX Quadcopter

The Blade 350 QX quadcopter is an almost-perfect example of its class. Three flight modes provide almost the perfect range from well behaved and safe to crazily agreeable to any insane set of control inputs you supply.

Blade 350 QX

Blade 350 QX

It is light, provides a reasonable flight time with the supplied battery, and you’re pretty well guaranteed to have more fun than you expect fooling around with it.

But that’s not all. The 350 is powerful enough, and stable enough, to carry a Go Pro camera and take awesome HD movies and stills from the air. You can spin the quadcopter in place and create a fabulous pan, or fly right up to something you otherwise can’t get to and take a closeup. Or just fly around and take a look at the countryside.

Everything you need is supplied in the package; the quadcopter, the hand controller, batteries, a charger (12 vdc… meant to hook to your car’s electrical system so you can recharge in the field), and you even get a set of extra blades. Which you are unlikely to need if you are even just a little bit careful. The manual is a little dense, and because of that you’ll have to read it carefully, but everything you need to know is actually in there within twelve pages.
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Kenwood TS-990S Review

ts990sI’ve been operating the Kenwood TS-990S for some months now, so it’s about time I actually review it. This review reflects operation under firmware 1.05 as downloaded from the Kenwood website.

Because there have been a number of reviews that have done an excellent job of enumerating the radio’s features, I’m going to come at this differently. I’m going to first give you an overview of how well I think it operates and how comfortable I’ve become (or not) with its features, along with an assessment of its value with regard to its capabilities. I’ll note a few things that seem unique to me, standout features that are really special from the operations standpoint.

Then I’m going to lay out, in detail, the critiques I have of the radio from an operating point of view — that’s something no one has really gone into as far as I know, and I hope you’ll find it useful. I even nurse a vague hope that Kenwood will, via Google-fu or some kind soul, find this and take some of my ideas to heart, because I really do think the radio could be significantly improved with just a firmware upgrade (or several.)
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Something for you CW types

You know, I have to confess: CW isn’t my favorite operating mode. It’s ok; sometimes I tune down to the CW portions of the ham bands and copy it for a while just to keep my hand in, but not too often. Consequently, another confession: I’ve not looked really hard into SdrDx’s CW handling until today. When I did, I found there were improvements that could be made, and, because I’m somewhat compulsive, I went ahead and made them, and you’ll find them in the 2.12r OSX beta that’s available for download as of right now. But don’t stop reading yet, please.

My old J-38 straight key

The first thing I did was some work on the high and low adjustment ranges of the CW mode demodulator envelope; CWL now allows from -10 to -1500 Hz, CWU allows from 10 to 1500 Hz. These are sane ranges; previously, it was a little weird, and I apologize for that.

The second thing was change the demodulator envelope adjustment from 100 Hz/step to 50 Hz/step. This allows you to create a properly centered demodulator envelope of an odd width, such as 300 Hz, or to cut the bandwidth all the way down to 50 Hz — a little extreme perhaps, but amazingly usable if the received station is stable.

Lastly, I experimented a bit with the audio notches to see how to best tailor the audio, and I found that with the Q of a notch set to about the third hashmark from the right of the Q scale, the notch was narrow enough to sit right on the upper edge of the demodulator envelope. I’ll give a detailed example:
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Waiting for the new Mac Pro

A

Waiting...

Waiting…

pple announced a new Mac Pro today; twice as fast as the current model, which itself is faster than the one I presently own. But that’s all they did. Announce it. It’s not ready, there’s no date, there’s no price, and other than “faster” and “supports three, 4k displays” and “much smaller footprint”, there isn’t much other information either.

Sigh.

On other fronts, they’ve finally fixed the multi-monitor shortcomings in OSX; menus, full screen apps, etc. Kudos. Even iOS got a little love with folders that can hold many files, instead of just a few.

The new OSX makes me willing to go for a new Mac Pro, or at least, it seems that way with the limited information I have now. I can put the old fella up in the ham shack where it will do a fine job with the SDR up there; and the new hotness will (of course) drive my desktop, save me time on compiles and just about anything else… and I admit, I run my SDR from my desk even more often than I do in my ham shack. Not just testing, I like the sound of a radio in the background.

The question is, newest model that can only run three displays and has only a small internal SSD? Or the current generation that can do more displays and has room for standard internal HDs?

Apple really does test my patience. It’s been several years since they really gave the Mac Pro much attention, and frankly, I was getting close to building a Hackintosh or buying the current generation. Will they get the Mac Pro out in time? Should I go for newness, the current generation, hacking, or something used off EBay? I feel information-deprived.

Tune in this fall for the next installment of “As the Apple Worms.”

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Marantz MA700 troubleshooting

I have quite a few Marantz MA700′s; of the group, four of them exhibit random popping sounds of moderate energy at the speaker output with no audio input to the unit. Clearly this is a very common failure mode for the MA700.

I have opened one of the “poppers” up on the bench, and with the buffer amplifier signal cable to the power amplifier disconnected, the popping noise remains, so it’s definitely not in the audio path on the buffer amplifier board. The buffer amp is connected to the power amp via an electrolytic, so there’s no problem unplugging the buffer from the power amp.

There’s another problem with this unit, too: I see somewhat random engagement of the high power rail mode for the amp, but this is not co-incident with the clicking coming from the speaker.

When the high/low power state switches randomly, the associated relay clicks, which is audible at very low volumes, and this is obviously not the design intent. Erratic high/low power switching problems are going to be nearby QU05, very likely the electrolytic CU08, the diodes DU01 and DU02, or QU05 itself. I’d suspect CU08 first.

The main amp PCB shows evidence of excessive heating towards the front of the chassis, where the driver section is located. Unfortunately, it looks to me that the mechanical assembly is complex with regards to the main amp and attached heat sink; taking it apart looks to be quite a big deal, my vision has become very poor, and I don’t actually need the amp, so I’m just going to close up. However, at least this exonerates the buffer amp and provides a pointer as to how to troubleshoot high/low rail power issues.

If anyone locates a specific component that is responsible for the clicking and popping, I would very much appreciate hearing about it; I’m willing to hack in a replacement electrolytic from the component or solder side of the board if that’ll solve the problem. Likewise, if circumstances lead me there — if one of my working MA700′s fails and I really need to fix one of these “poppers” — I’ll post what I’ve learned.

I’ve put the service manual for the MA700 online here.

–Ben, AA7AS

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WLO RTTY News Feed Replaced with Weather

Sad news for RTTY SWLs, WLO’s newsfeed at 8472 kHz is gone, replaced with weather broadcasts. The weather broadcasts alternate between RTTY and SITORB, just as the news feed did, but that’s the end of the similarity.

Well, it was nice while it lasted. Sigh.

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New OSX and Windows version of SdrDx – 2.11

SdrDx 2.11 adds visible memory markers, an enhanced internal database, better panning window width by window width, a number of fixes and performance improvements, and additional documentation.


  Screen shot: http://www.flickr.com/photos/fyngyrz/8165852338/in/photostream/lightbox/
    Downloads: http://fyngyrz.com/?p=915
Documentation: http://fyngyrz.com/sdrdxdoc/sitemap.html
      Changes: http://fyngyrz.com/sdrdxdoc/changes211.html

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