From my Twitter feed: diode ring mixers, TAPR news, SDR SA

Stefano_NVR's avatarDr. NVR @Stefano_NVR
How a Diode Ring Mixer works | Mixer operation theory and measurement: youtu.be/junuEwmQVQ8

 

ke9v's avatarJeff Davis
Summer 2014 TAPR PSR Journal Available –> tapr.org/psr/psr126.pdf #hamradio

 

EDNcom's avatarEDN.com @EDNcom
RT @measurementblue: Michael Dunn tries The $11 spectrum analyzer & SDR ubm.io/1q5JI5W @EDNcom @EDNMichael ow.ly/i/645Dp

 

rtlsdrblog's avatarrtl-sdr.com @rtlsdrblog
BeagleBone Black Image File with RTL-SDR + GNU Radio + More rtl-sdr.com/beaglebone-bla…

Next year, let’s do a “maker” Field Day

A couple of minutes ago, I got an e-mail from John, KD8MKE, who wrote:

I had this crazy idea that you could use a quad copter to hold up a dipole antenna AND power the quad from the ground (to save the battery weight).  Ed pointed out that the cable would weigh quite a bit, which is a good point.  Modern quads are remarkably steady when they are in loiter mode.

I wondered if you had heard of someone doing something like this at a Field day?  Seems like it would be handy if you didn’t have a tree or other structure to use as a peak.

I replied:

I haven’t heard about the use of copters for actually supporting the antennas, but there has been talk about using them for getting ropes into trees.

In the past, people have used balloons to support vertical antennas. With a vertical, you’d need only support the wire itself, not the feedline. A 160m vertical would be about 133 ft. long. How far up can these things go? How long do you think they would stay in the air?

I thought about this for a bit, and it occurred to me that next year we should do a Maker Field Day. The idea would be to incorporate as many “maker” projects as we can think of into it. Copters are a big maker thing, so that certainly qualifies. Another idea that I had for a maker ham radio project is to use 3D printing to make a “cootie key” or a paddle.

What are some others?

From my Twitter feed: SDR, SWL, kits

sdrsharp's avatarsdrsharp @sdrsharp
You want more and better rtl-sdr tools? Consider helping this initiative from Kyle Keen indiegogo.com/projects/a-mon…

 

UlisK3LU's avatarUlis K3LU @UlisK3LU
Western radio broadcasters tuning out (excellent article on the demise of #shortwave broadcasters) via Straits Times shar.es/LgFv9

 

wa1gov's avatar#hamradiopic.twitter.com/oaBaj00Ady

From the trade magazines: free design tools, DSP, education

Top Free DIY Tools Ever Engineer Needs. We’re seeing a relative explosion in free tools for engineering electronics. Some of those online tools prove to be worthless, and it’s back to blind searching or some paid tool. To help sort out the nonsense from the useful online tools, check out this list.

What Do You Know About DSP? Louis Frenzel, who is a ham by the way, reminisces about his experience with digital signal processing (DSP) and recommends a new book for those just learning about DSP.

Outrageous! Experience is no qualification to teach EEs. This is another column by Louis Frenzel. He writes:

It is obvious that the colleges do not value industry experience when it comes to hiring professors….It seems to me that professors with real world experience could teach the fundamentals in context and to explain what is really important and what is simply nice to know. Experienced teachers would be able to teach students things they ordinarily do not teach in school. They could tell their design war stories and explain that troubleshooting is just as important to know as design. I think that an MSEE with ten good years of experience is more qualified to teach than a no-experience PhD.

Use VLF to detect lightning

Yesterday, my friend Ed, KD8OQG tweeeted:

vielmetti's avatarEdward Vielmetti @vielmetti
a lightning detector, picking up lightning signals on VLF (!) blitzortung.org/Documents/TOA_… @kb6nu @hoopycat #hamr

Ed is a bit of a severe weather geek, and is often Tweeting when severe weather rolls through the Ann Arbor area. So, it’s only natural that he would be interested in the Blitzortung project. The Blitzortung website describes the project this way:

Blitzortung.org is a lightning detection network for the location of electromagnetic discharges in the atmosphere (lightning discharges) based on the time of arrival (TOA) and time of group arrival (TOGA) method. It consists of several lightning receivers and one central processing server. The stations transmit their data in short time intervals over the Internet to our server. Every data sentence contains the precise time of arrival of the received lightning discharge impulse (“sferic”) and the exact geographic position of the receiver. With this information from all stations the exact positions of the discharges are computed. The aim of the project is to establish a low budget lightning location network with a high number of stations. The price for the hardware used is less than 200 Euro. The sferic positions are free accessible in raw format to all stations that transmit their data to our server. The station owner can use the raw data for all non-commercial purposes. The lightning activity of the last two hours is additionally displayed on several public maps recomputed every minute.

Blitzortung.org is a community of station operators who transmit their data to the central server, programmers who develop and/or implement algorithms for the location or visualization of sferic positions, and people who assist anyway to keep the system running. There is no restriction on membership. All people who keep the network in operation are volunteers. There is no fee and no contract. If a station stops pooling its data, the server stops providing the access to the archive of sferics positions for the user of that station. A detailed description about how to participate to the network and how to setup an own receiver can be found in the following document.

The website doesn’t say how much a setup costs, but does says, “If you are interested to setup an own station then you can get the latest printed circuit boards and the programmed micro controller from us. If you are not from Germany, Austria, or Switzerland you can even get a complete controller kit, a complete amplifier kit, ferrite rod antennas, and a GPS module for cost price, if desired.”

The Cloud is an interactive lamp and speaker system, designed to mimic a thundercloud in both appearance and entertainment. Using motion sensors the cloud detects a user's presence and creates a unique lightning and thunder show dictated by their movement.

The Cloud is an interactive lamp and speaker system, designed to mimic a thundercloud in both appearance and entertainment. Using motion sensors the cloud detects a user’s presence and creates a unique lightning and thunder show dictated by their movement.

Ryan Burns, one of Ed’s followers and head of A2 Geeks, suggested that he get a Cloud and hook it to the detector. According to the Cloud’s website, “The Cloud is an interactive lamp and speaker system, designed to mimic a thundercloud in both appearance and entertainment. Using motion sensors the cloud detects a user’s presence and creates a unique lightning and thunder show dictated by their movement.” We would, of course, have to get a version without the motion sensors so that we could interface our lightning detector.

I volunteered that we could mount the detector’s antenna to the tower at the Hands-On Museum. Ironically, I think that we’d have to use a lightning arrestor on the feedline should we actually mount it outside.

From my Twitter feed: wire splicing, SDR, BCB loop

kd0bik's avatarJerry Taylor @kd0bik
How-To: Splice Wire to NASA Standards fb.me/3BMl1CsL0

 

rtlsdrblog's avatar<b”>rtl-sdr.com @rtlsdrblog
Using and RTL-SDR and RTL_433 to Decode Various Devices rtl-sdr.com/using-rtl-sdr-…

 

ke9v's avatarJeff Davis @ke9v
@AA7EE goes mad scientist with his Tuned Loop for BCB –> aa7ee.wordpress.com/2013/11/17/a-t…

From my Twitter feed: new EchoLink for Mac, SDR

dusty_s's avatardusty_s @dusty_s
EchoHam (formerly EchoMac) update in Mac App Store” <- glad to see an update! feedly.com/e/G5x1odQW

 

dangerousproto's avatarDangerous Prototypes @dangerousproto
OHM2013: Hacking the radio spectrum with GNURadio goo.gl/krngx7

 

VA3BCO's avatarBrian (VA3BCO) @VA3BCO
Are we Getting Closer to a Touchscreen SDR HT? >#hamr #hamradio wp.me/p4GMgg-28

From my Twitter feed: Tindie, resonant speaker

blackrockcastle's avatarBlackrock Castle @blackrockcastle
@WIRED: An inside look at Tindie, a thriving new marketplace for DIY gadgets wrd.cm/Rlnkbt pic.twitter.com/pZzItSsUpz@ado_collins

 

n1pce's avatarJohn Ryan @n1pce
April 2014 CQ Plus – Adding Volume With a Resonant Speaker youtube.com/watch?v=nLFPAj… via @YouTube

 

kc5fm's avatarkc5fm @kc5fm
My New Favourite Social Network Is Ham Radio | Business Insider bit.ly/1k5fGIx #ARRL #hamradio

Makers should make things that work

In the March/April issue of CQ, Rich, W2VU wrote the “Makers” column for the regular editor. He writes about a one-tube transmitter that he built. It sounds like an interesting project, but then he says:

I haven’t actually gotten to testing it out yet. I still need to get a crystal and wire-up the connectors for power, antenna, and a key….Frankly, I don’t really care if it works (that would be a bonus, of course), but for me, the real fun was in the building (I’m sorry, making), from staining the wood to winding the coils and putting it altogether. As far as I’m concerned, it’s a piece of electronic art that I’m proud to have in my shack.

While I agree with W2VU that it does look very cool, I would really want to do what I can to make it work. While it might be fun to look at, the real pleasure comes from building something that you can put on the air and make contacts with. Makers should make things that work.

How do you know that fuse is protecting your circuit?

How do you know that this fuse will protect your rig?

How do you know that this fuse will protect your rig?

I blog for a leading manufacturer of circuit protection devices, so I keep my eye out for articles on fuses, ESD diodes and the like. Recently, I came across the article, “Fuse selection factors critical to circuit design.” Among the factors discussed is:

11. Application testing/verification prior to production.
Request samples for testing in the actual circuit to verify the selection. Before evaluating the samples, make sure the fuse is properly mounted with good electrical connections, using adequately sized wires or traces. The testing should include life tests under normal conditions and overload tests under fault conditions to ensure that the fuse will operate properly in the circuit.

Being a former test engineer, this got me to thinking about how one would actually do this. For example, how would you test that a fuse will actually protect a circuit board? Would you inject faults, i.e. deliberately short-circuit nodes? If so, which ones?

What measurements would you make to ensure that the fuse was working as you hope? Would you measure the time elapsed between the time you injected the fault until the time the fused actually blew? How about measuring the current profile over that period of time? That might be important and/or tell you something about the failure.

What kind of fault analysis should you perform after the fuse has blown? I suppose at the very least you’d want to replace the fuse and ensure that the circuit is functioning again. I would say that you should also run a full performance test to ensure that the fault didn’t adversely affect the board’s performance. Also, I’d think that you’d want to visually inspect the board to ensure that the fault current didn’t damage the board or traces at all.

I’m curious if any of you have had any experience with this kind of development testing. If so, please e-mail me or comment here.