August 9, 2016
and the Small
Wonder Labs SW30+ Transceiver
Installment #6 ...
Rx Product Detector & Audio
and ... "Anatomy of a Homebrew Station"
and build-up of the classic 2-watt 30-meter superhet transceiver
designer Dave Benson K1SWL of Small Wonder Labs.
We're closing in on the completion of the SW30+ build-up! This
time we take the output of the crystal filter and mix it down to audio
baseband in order to get the CW tone we hear in our headphones.
So with this episode we'll start continue studying the Big Picture seen
in the diagram "Anatomy of a Homebrew Station", and
then "zoom in" on a
couple of accessories (DSP audio filter and a simple keyer) as they are
being built-up by intrepid homebrewers.
A couple of BIG ANNOUNCEMENTS happen in this episode! ...
1) We are announcing a Contest
for SW30+ Kit owners to strut their stuff! Over the course
of the next couple of months we challenge the kit builders to do
their best, and be judged in three categories: best original
packaging, best packaging in the red pcb enclosure, and best
accessorization. Some cool prizes are being offered ... The
Contest Details page has all the
2) Live Video Feed! In
this episode we are broadcasting a live video feed via the Zoom
conferencing tool ... at the same time as using our ever-faithful
Teamspeak audio client. Using the same computer that you're
using for Teamspeak, or even using a second computer/smartphone/tablet,
https://zoom.us/j/216305883 and let Zoom set things up
for you. If all goes right, you'll see one/both of your
friendly hosts as we show live views of the projects during the
show. Just put your Zoom client on mute and watch the
show, as you listen and speak on the show using Teamspeak per
usual. Pretty cool, eh?!
you say you missed the last episode? You can download the podcast and
catch up on things at any time! The whiteboard material and audio
recordings for all shows are listed right there on our home page! (www.cwtd.org)
73, George N2APB and Joe N2CX
Discussion During Show ...
<20:29:04> "Alan W2AEW": I see you've got the Laserbeam DSP audio
filter coming up on the whiteboard. I just got one of these, and
plan on putting a video review together in the weeks to come...
<20:33:35> "Alan W2AEW": servo tape
<20:36:59> "Joe N2CX": SOTA DSP filter $32.3* (US) + shipping
<20:39:06> "Pete wb2qll": SOTA also makes a variable width audio
filter at US$49:
<20:39:59> "Joe N2CX": Thank Pete, the one I showed was the first
"hit" on Google.
<20:47:22> "Alan W2AEW": You can use just one output if you want to
drive a grounded load. Leave the other open
<20:53:24> "Alan W2AEW": I have a video tutorial on the Gilbert Cell
mixer (like in the NE602/SA612). The tutorial can be found here:
<20:53:26> "Alan W2AEW":
<21:05:21> "Obe - KC4VZT": Good night and thanks for another good
show, loved the video.
(Click here if you
want to get straight to the Elmer 101 feature material farther down the
Anatomy of a Homebrew Station
Here is a powerful block diagram representing the
many varied possible "accessories" that we homebrewers have
available to us in one form or another.
An interesting aspect of this diagram, however, is that all these
accessory functions can be integrated quite nicely with the SW30+
rig ... or just about any other one!
Another interesting perspective, that will be explored in greater
depth in numerous future episodes of CWTD is the "project" nature of
(Envision, if you will, that each of these accessory functions
can_and_will be fully designed and chronicled within the CWTD
Projects section of our website!)
Further, this diagram becomes a "clickable roadmap" that links each
item represented here to the respective project on the CWTD website.
So ... Try clicking on the images below!
... Soon we'll be populating each one of the pages linked
in the diagram to actual, in-progress projects that we all
can build and use!
N2CX Bench Tips
1. Effect of
spacing of L1 turns (SW30 VFO)
As turns are spread or compressed on toroid, self capacitance
As first wound, tuning range
was 2.430 to 2.463 MHz
With turns compressed it was
2.385 to 2.417 MHz
With turns spread out it was 2.445 to 2.478 MHz
Total adjustment range by
adjusting turns layout was 60 kHz
2. Use the KX3
to check VFO frequency of the SW30
The KX3 tunes from below AM
broadcast band to 30 MHz (and 50 - 54 MHZ)
Set Mode to CW
with "wide" bandpass. Use tuning in 100 Hz steps
Run 18 in. insulated wire
from the KX3 antenna jack and lay it alongside SW30 transceiver pc
Tune the radio until loud
beat note heard - it helps to know approx. frequency
AA0ZZ EZKeyer 2i (Internal) ... Perfect for the SW30+ in either the
Primary or Accessory enclosure
2) SOTABEAMS "LASERBEAM"
DSP Audio Filter ...
The new range of ready-made
LASERBEAM-DUAL digital audio filter modules are the perfect addition
to your project or even to your existing radio. Unlike analogue
filters, digital filters provide near-perfect characteristics.
Because of the way that they are implemented, they are better than
analogue filters in almost every way!
LASERBEAM-DUAL Modules have
been designed for ease of use. Each module has two filters onboard.
There are three combinations to choose from:
The General Purpose
module has a narrow CW filter (550 - 850 Hz) and an SSB filter
(300 - 2700 Hz)
The CW module has two
narrow filters (550 - 850 Hz) and (300 - 1300 Hz)
The SSB module has a
standard SSB filter (300 - 2700 Hz) and a narrow SSB filter (300
- 2400 Hz).
CWTD Episode #83:
Elmer 101 and the SW30+ Transceiver
Rx Product Detector & Audio Amp
First, a few Notes:
Kits & boards are sold out.
Blank enclosure kits are available from
FreqMite Kits now from
... And AA0ZZ shows
how to connect it to your SW30.
Accessories in progress ... Keyer Kit, Display,
Arduino control, Spectrum output
For the latest & greatest SW30+ Kit information,
see/download the Updated Manual