The personal website of Scott W Harden
Source code for Built a Pixie II
---
title: Built a Pixie II
date: 2009-05-07 15:10:22
  - amateur radio
  - circuit
---

# Built a Pixie II

__Man, what a long day!__ Work is so tedious sometimes. This week I've been proofing scientific literature using Office 2003 with "track changes". I make changes, my boss makes changes, I make more changes, and it goes back and forth a few times. I wonder why office 2007 is so bad. Does _anybody_ truly like it, and find it to be a significant improvement upon 2003? ... or Vista over XP? Maybe I'm just getting old, inflexible, and grumpy.

<div class='center border'>

![](proofread.jpg)

</div>

__This is what I'm currently working on.__ The light bubbles on the right are deletions. The dark bubbles on the right are comments. The red text is insertions/modifications I made. Pretty intense, right? Pages and pages of this. I'm starting to grasp the daunting amount of time a scientist must spend _writing_ in the laboratory as opposed to performing actual experiments or even doing literature research.

<div class='center border'>

![](pixie2.jpg)

</div>

__Last night I assembled a Pixie II__ circuit similar to the one pictured here. I must say that I'm a little disappointed with the information available on the internet regarding simple RF theory in relation to transceiver circuits. I'm just now starting to get into RF circuitry and the concept looking at circuits and imagining a combination of AC and DC flowing through it is warping my brain. I have everything I need to build a simple Pixie II transceiver (which is supposedly capable of Morse code transmissions over 300 miles, and QRSS applications over 3,000 miles) but I don't want to use it unless I understand how it actually works.

<div class='center'>

![](pixie2transceiver.gif)

</div>

__I'm trying to break this circuit down into its primary components.__ I understand the role of the lowpass filter. I understand the role of the 1st transistor and related circuitry in amplifying the output of the crystal oscillator (left side). I totally get the audio amplifier circuitry (bottom). It's that center transistor (which supposedly handles signal amplification, receiving, and mixing) that I can't get my mind around. Every time I think figure it out for one mode (sending or receiving), I mentally lose the other one. It has me very frustrated because it seems like this should be easier than I'm making it. I selected this circuit because it was simple and I assumed I'd be smart enough to figure it out... maybe I was wrong? I wish I had an oscilloscope so I could probe the RF passing through various stages of this circuit. I guess I should take another stab at reading chapters 5-11 of the ARRL handbook.

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