All posts by Brian Smigielski

Feb 18 DSO138 Kit Building Tips

Hi DSO138 kit builders,

I wanted to share some tips to follow for our 18 Feb Kit Build from 1-4pm. As I already built my own kit, I wanted to share some advice.
I know not all of you can attend, but for those of you who can, please read below. I’ll also post on website along with some pics.
  1. Make sure you bring a magnifying glass AND a multimeter. Also might help to bring an LC meter too (though I didn’t have one at the time) The color bands on the resistors are particularly impossible to see, so I had to measure the resistance of every one. I even did it 2-3 times to make sure I was right.
  2. To test your kit at the end of the night, you need to supply it with power. You can do this 2 different ways. The first is bringing a 9V battery along with 9V battery leads terminating at the end of a female port as shown below. The second, is grabbing a power adapter rated for no higher than 12 V again terminating on a female port with pic show below.
  3. You might want to bring a small Phillips head screwdriver (for eye glasses) in order to perform probe calibration.
  4. If you want, bring your laptop so you can download some signal generators (using your sound card) in order to play with the oscilloscope. In order to do this, I ended up using a BNC to audio adaptor which I purchased off of Amazon Prime. I’ll bring mine in case you don’t have one
  5. If you have a standalone signal generator, please bring it, along with BNC wire connections for the oscope.
DSO138 power supply port
9V battery adaptor
12V power supply (stolen from a Linksys router) with port (top-middle)

In order to do some testing, we are going to want to use either signal generators that club members graciously bring in, or you can use your laptop’s sound card. To that end, Mike (K1WVO) suggested a really nice link to do this.

I’ve tested most of these and they work fine on my scope.

If I have any other thoughts, I will update this post.

Thanks and 73,

Brian, AB1ZO

Amateur Radio at MakeIt Labs

On Saturday, January 28th the Nashua Area Radio Club (Nashua ARC) will be hosting a special event for Interested kids, parents, and friends in the community about the joy of amateur radio at MakeIt Labs in Nashua from 9:00 am – 3:00 pm. You may drop in at any time and stay as long as you like to participate! Among our activities, you can:

Get-On-The-Air Station (GOTA)

This is amateur radio at its best and what it’s known for! We invite you to get on the air and make a contact (we call them QSO’s — pronounced: cue-so) somewhere in the world! You might be able to make a new friend in Germany or even Japan! Making contacts sits at the heart of amateur radio and is an activity that brings people together. So don’t be shy, step up, and hit the push-to-talk button!

Satellite Station Display

The Radio Amateur Satellite Corporation (AMSAT) began in 1969 to foster amateur radio participation in space research and communication. Currently, AMSAT groups help advance the state of the art in space science, space education, and space technology. Come learn about what components go into constructing a station capable of contacting a satellite and what antennas, and smart phone apps, operators use to keep a pulse on the satellite location.

Digital Amateur Television (DATV)

DATV Transceiver RackNot only are amateur radio operators granted privileges to transmit speech, but we also can send fast-scan data such as TV signals! Many operators have experimented with how to homebrew their own fast-scan TV stations, and our club president Fred (AB1OC) and our member Skip (K1NKR) have chosen to use construct a station which uses a Raspberry Pi (RPi) with an Arduino shield to sit at the heart of the transceiver. The RPi is the brains of the TV which runs Linux and among other things is responsible for sequencing, transmit / receive control, automatic VSWR monitoring, and a touch-screen controlling interface to configure and operate the system. Learn about what it takes to build and operate one of these stations. We may even be able to make a contact! More information can be found at https://stationproject.wordpress.com/category/amateur-television/.

Kit Building with Nashua ARC

The Nashua ARC holds kit-building nights where both inexperienced and experienced members homebrew in a relaxed, learning environment. In the past we have built Pixie QRP (low-wattage) kits transmitting Morse Code on the 40m amateur band. But, on February 18 from 1 – 5pm, First Church in Nashua, Nauss Hall, we will build the digital oscilloscope kit DSO138 (shown to left). This kit comes with a clear acrylic case to protect it, build instructions, and among its specs has a 1 Msps sampling rate, 12 bit accuracy, 200 kHz bandwidth (good for audio signals), capable of freezing the waveform display, and comes with a 1Hz / 3.3V test source. We invite you to join us and will bring some kits with us. More info can be found on our website at http://n1fd.org/2016/03/27/inexpensive-diy-digital-oscilloscope-kit/.

We hope you will join us for our event! Please bring friends, family, but most importantly we want you to have fun and enjoy this hobby with us!!

Contact Information

Brian Smigielski (AB1ZO): bsmigs@gmail.com
Jamey Finchum (KC1ENX): jamey@finchum.net

A First Homebrewed Transceiver

I recently wrote an article about Nashua ARC’s 2017 Project Night (forgive my shameless self-promotion). In it, I expressed my awe of what our club members can do, and how it has inspired me to attempt my own first build.

The winter really is the best time to do this. And it’s time for me to embark on this journey of fun, learning, and frustration! So I turned to Mike (AB1YK) who knows about such things, since he and I are attempting to organize a future summer weekend Tech Build Event for the club. The Pixie and the DSO138 oscilloscope are the warm-ups for this main-event. One suggestion Mike threw out was a Direct-Conversion Receiver (DCR) as advertised in the January 2015 issue of QRP Quarterly which you can actually download here (and as far as the application to the Tech Build goes, perhaps we only build parts of the DCR given time constraints). This article is entitled Let’s Build Something: Part I by Ben Kuo (KK6FUT) and Pete Juliano (N6QW).

In it, they outline the main building blocks of the build. The nice thing about this build is once one is done, it is amenable to some modular alteration to turn it into a fully working QRP SSB transceiver! (Though I do not know how much wattage at this stage) The other nice thing about this build is all the parts are clearly labeled and Pete provides links at the end of the article for YouTube videos about the build. Maybe it’s just my noob eyes, but I find the videos moderately useful for someone starting from scratch, but I can see the utility for a more experience builder. Additionally, this build utilizes the Manhattan style of building. I find this optimal for someone just starting out because I can easily visualize all the connections between the components and have relatively easy access to make measurements and tests with probes.

Let’s go through parts and I’ll tell you what I know (at a cursory level) and what I don’t

  • 40m bandpass filter: Totally on this one. I’ve never built a filter before but looking forward to doing this. In fact I need to build one for my ADS-B antenna at 1090 MHz, but it doesn’t seem feasible to do from components at that frequency. Any ideas anyone? I’m kind of stumped.

  • RF amplifier: REALLY looking forward to tackling this one, but this won’t be the first thing I do. Makes sense to have for weak signals.

  • Double-balanced mixer: Now I know something has to knock the RF down to an intermediate frequency (IF) and when I see mixer, this is where my brain goes.  The double-balanced bit was foreign to me, but as advertised in the article (‘double balanced’ implies that the original signal and local oscillator frequencies are deliberately nulled out as part of the mixing process and do not appear at the output.)

  • Arduino Based Sample DDS: In order to even produce an IF, we need a local oscillator (LO). This is where the Arduino comes in. The authors argued they looked at a number of options for the LO including a VFO (variable frequency oscillator), varactor tuned oscillator (should know this from my Extra exam — but full disclosure — I can’t help you now), and a DDS (direct digital synthesizer). They felt the simplest option was the DDS (hence the Arduino).

  • Audio amplifier: We want to amplify the audio signal so we can hear it through our 8 Ohm speaker!

So now if you put all the components and modules together, you arrive at something which should look like:

I like this project for a few reasons.

  1. It’s a more interesting build and takes longer than 2 hours.
  2. It will have amateur radio applications in my shack. I do hope to work some pretty cool QRP with this rig (when I turn it into a full-on transceiver).
  3. I will learn A LOT about the electronic components integrated into the rig and be able to have an excuse to buy some test equipment.
  4. I get to work on my soldering skills.
  5. The modular design is attractive so that if I wish to make alterations in the future, it seems I will readily be able to do so without having to tear the entire rig apart.
  6. Understanding, at the end, how all of these parts function together to make my transceiver work. I look forward to sharing whatever knowledge I accrue during this build with future amateur radio hobbyists just breaking in.

I will certainly post articles as my progress commences. Currently, I am in the market to buy components and test equipment and will begin to build probably the simplest module first; currently that seems to be the filter. And I have learned a very valuable lesson from being in the club and participating in its activities that I am applying to this build. Initially do things to set yourself up for the highest probability of success so that you keep your morale, interest, and momentum high. Nothing is worse than diving head-first into the hardest part of a project and losing any and all ambition when things begin to not work (and they will…).

73,

Brian (AB1ZO)

January 2017 Project Night

I wanted to take another moment to share a few thoughts about last night’s Project Night. Sometimes, when I’m speaking on the spot, everything I want to say doesn’t come to me all at once, so please bear with me again.

I really was very impressed by the level of talent that was showcased. And, more importantly, I know there is even more of it out there amongst the folks who didn’t get the opportunity to present. But I hope you will during a future club meeting.

Dennis, K1LGQ At Project Night
Dennis, K1LGQ Shows QRP Kits at Project Night

The Jan 2016 Project Night was my first Nashua Area RC meeting. And, it was that first meeting which played an instrumental role into sucking me completely into the hobby: and I’m in pretty deep right now.

I’ve noticed over my years on this pale, blue dot that part of my personality is to think big, try to generate a lot of ideas, but then sometimes get fearful to execute. I think it’s because I’m afraid to fail and I’ve convinced myself (probably through some poor advice by the few poor mentors I’ve had in my life) that I should be able to do everything on my own. My graduate school advisor once told me after someone’s defense that a good physicist should know everything. (Crap! What should a great physicist know then?) If you’re a theorist, you should know every experiment being done. If you work on string theory, you should also know solid-state physics incredibly deeply. This is of course complete and utter non-sense. But, nonetheless, I still lean on that ethos like a bad crutch — but I’ve been doing it less.

Charlie, AB1ZN Showing A Vintage Rig
Charlie, AB1ZN Showing A Vintage Rig

Project night helped served to snap me back to reality. There I saw people work for months on projects, and no doubt encounter obstacles and challenges along the way, and they happily discussed who they went to for help and even welcomed advice and Elmering from club members after the presentations were finished. It was clear they were not discouraged by the challenges they knew they would face, and the time being invested into their project. And honestly, it made me feel a little better to see that even the best of us get stumped and need to collaborate. In fact that is expected.

Hamilton, K1HMS Explains CPLD Technology
Hamilton, K1HMS Explains CPLD Technology

We have many experts in the club. Hamilton, (K1HMS), did a great job presenting a super-technical talk about CPLD’s.

Anita, AB1QB Demonstrates her Raspberry Pi DX Alarm Clock
Anita, AB1QB Demonstrates her Raspberry Pi DX Alarm Clock

Anita, (AB1QB), had a really entertaining and pedagogical talk about software, DX spotting, Raspberry Pis, and annoying Fred (AB1OC) with DX alerts.

Mike, AB1YK Shows His Home-Build Transceiver
Mike, AB1YK Shows His Home-Build Transceiver

But one talk which really stood out in my mind was given by Mike (AB1YK) who said during his talk that he’s mainly a digital guy with a ton of Arduino experience. But, he was interested in diving into the analog world, and so his first foray into that world, was to construct a QRP transceiver from scratch and teach himself what he needed.

Jeff, WA1HCO Shows His Optimized Matching System
Jeff, WA1HCO Shows His Optimized Matching System

What last night was for me was inspirational. It gave me the peace of mind I needed to believe I can tackle subjects I really don’t know much about at all, and be somewhat successful at it. I won’t be a Hamilton, but I’ll know enough to make me dangerous, and that’s good enough for me.

Thank you Nashua Area RC members for opening my eyes, again. I look forward to crossing some of the projects I want to get busy on, off my list.

73,
Brian, AB1ZO