With my CW Messenger project complete, I can loop back to my S-Pixie project again and begin testing its transmitter. I’ll use the CW Messenger to help with testing until I become proficient in CW. I’ll start with some simple calling CQ tests of the PCB build, mostly because I’m curious to see what this …
CW Messenger: Protoboard Build Start to Finish
This is a compilation of posts I made on the r/HamRadioHomebrew Reddit community documenting my build of the CW Messenger. I’ve expanded on those post where appropriate to provide more detail on the build. It’s Like a Puzzle I started the CW Messenger build by imagining the final protoboard with all of the components on …
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CW Messenger: Prototype Testing
I built part of the CW Messenger on breadboard to further test the CW Messenger software. Here is a video of it “sending” message #1 (note that I haven’t modified the author’s original stored messages yet). Notice anything in the video? The software is working as expected, but the buzzer is only clicking. That’s strange! …
CW Messenger: A New Project
I came across a book, Microcontroller Projects for Amateur Radio, that has a number of interesting projects that may interest some of you. Chapter 10 covers a CW memory keyer (one down from the top on the left). I decided to put testing of the S-Pixie transmitter on hold to start this project. It should help …
S-Pixie: Audio Amplifier
The S-Pixie uses uses an LM386 as its audio amplifier (TI datasheet, note that I could not determine the manufacturer of the chip included in my kits). The design closely follows the design shown in Figure 12 of the datasheet. The 10 uF capacitor between pins 1 and 8 (shown as the two GAIN pins …
S-Pixie: Receiver Mixer Analysis and Testing
In the S-Pixie, the portion of the circuit including Q2 (8050 datasheet) serves dual purposes. It’s a mixer when receiving and a power amplifier when transmitting. Here is the relevant portion of the mixer circuit. When transmitting, the 10k resistor is shorted out by the CW key (not shown in the schematic above), biasing the …
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S-Pixie: Local Oscillator Redesign
Note that while this local oscillator redesign produces a better sinusoidal output it didn’t produce better audio output from the S-Pixie. This is because the mixer loads the local oscillator circuit, producing a signal very similar to the original design. I found that coupling the local oscillator and mixer with a 100 pF capacitor instead …
S-Pixie: Local Oscillator Analysis
If you’d like to join the discussion of the S-Pixie local oscillator check out Ham Radio Homebrew Projects on reddit. The S-Pixie uses a Colpitts crystal oscillator. I found a great video by Craig (devttys0 on YouTube) that explains how it works and discusses design considerations. Local Oscillator Analysis I’ve been having fun following along with Craig’s …
New Reddit Community to Discuss Ham Radio Projects
I’ve started a new reddit community to discuss homebrew ham radio projects, r/HamRadioHomebrew. If you’re interested in homebrew ham radio projects or just like experimenting and tinkering with ham radio circuits, check out the new community and consider joining in on the discussion. It’s brand new so the current content is just my S-Pixie project, …
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S-Pixie: Pi Filter Analysis
I bought a couple of Super Pixie Transceivers when I was studying for my Technician license but only got around to playing with them now. The S-Pixie is a low power, CW transceiver that operates in the 40 meter band at a fixed frequency of 7.023 MHz. The design for the radio has evolved over …
Radio Circuits: Playing Around with a Crystal Radio
I’ve been taking it kind of slow with radio gear purchases since getting licensed. Being more interested in the technical aspects of the hobby, I’ve bought a few small kits to get started with but these have mostly sat waiting me getting the time to assemble them and getting an antenna up. I have built …
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Ham Radio: Got My Amateur Extra License
I got my Technician license at the end of March and given that the material covered in the General and Amateur Extra licenses builds on the previous material, I decided to continue on over the next two test dates to upgrade to these as well. There are many sources to study for the exams. For …
First Circuit Tests with the Digilent Analog Discovery 2
I got Digilent’s Ultimate Analog Discovery 2 Bundle to help with my journey into radio circuits. AD2 is an “USB oscilloscope, logic analyzer, and multi-function instrument that allows users to measure, visualize, generate, record, and control mixed-signal circuits of all kinds. ” Digilent is having a 15% discount sale making the bundle particularly attractive. The ultimate …
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A New Activity: Got My Ham Radio Technicians License
I’ve been spending some time off and on over the last several months porting the code generation part of cc65 to produce code for the 16-bit 65816 rather than its 8-bit cousins. I’m just doing a simple straight port at this point, only converting the generated code to take advantage of the 65816 16-bit registers …
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65816: Coding Efficiencies (last update: 3/1/2023)
I’m using this post to gather some of the coding efficiencies I’ve found in moving to the 65816. Most of these relate to porting my 6502-based Forth operating system. I’ve documented many of these findings in my code and I figured it was better to have them here in one place rather than there buried …
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