WA5BDU - Nick Kennedy's
Ham Radio Page
WA5BDU in the ham shack


I've been enjoying the hobby of ham radio since being licensed as WN5BDU in January, 1962 at the age of thirteen.  I've enjoyed many facets of this diverse hobby over the years, but I remain mostly a CW (Morse) operator.  On the air activities include casual QSOs and competitive events such as contesting and a bit of DX chasing.  Off the air, I'm building stuff or writing microprocessor code.

I've lately spent a lot of time involved with a development in ham radio which emphasizes small, simple (usually) low powered radios, called the QRP movement.  QRPers tend to use CW a lot and also like to build equipment from kits or from scratch.  The technical side appeals to me.

My Rig - Current Equipment

  • Elecraft K3 my main HF rig, KX3 for field.
  • Hallicrafters HT-40 1960s novice tranmitter
  • Drake 2B classic tube receiver with 2BQ
  • Heath VF-1 classic VFO from 50s & 60s
  • K8RA mini paddle
  • KT-34A 4-element triband beam at 48 feet
  • Lots of home built radios
  • ICOM IC706-IIGX for mobile & VHF
  • W6AAQ screwdriver antenna for HF mobile
  • ATS-3 sophisticated QRP rig in an Altoids tin
  • Begali Pearl keyer paddle
  • 130 ft dipole fed with 450 ohm ladder line
  • Line length switch for above
  • Quarter-wave inverted-L for 160 meters

History: My older radios and times

Technical stuff - my projects

One-chip receiver

A 40 CW meter receiver using the TDA1072 AM radio chip

 EFHW Antenna Matchers

The end-fed half-wave antenna is enjoying popularity for portable

use due to its ease of erection and no-feedline design

Here are two matching circuits for the EFHW

Introduction to LTSpice (pdf)
Introduction (Microsoft Word)
Tutorial #1
Tutorial #2

LT Spice is a free circuit analysis program.  It's easy to use but there

is the usual initial familiarization problem.  The link at the left is a PDF

file of  my introtuction and tutorial.  Download from the link below:


Permeability (current) controlled oscillator

A simple circuit from EDN which varies the frequency of
an oscillator by passing current through a toroid, changing
its permeability by saturation.  The result shows up in the
frequency of the oscillator.

Amplifier to boost DDS output

I have an NJQRP DDS and another designed by K6ESE both of which
put out a couple milliwatts of RF power.  This circuit boosts that to
about 5 watts for use as a QRP transmitter or to allow the DDS to drive
a tube-type transmitter.

A 60 meter SSB transmitter

This is a 10 watt SSB transmitter I designed and presented at
OzarkCon in Joplin in 2005.  

A simple autodyne receiver

An interesting receiver that can lock to the station being
received (such as WWV).  

Thermostatic fan control for MFJ-4225MV P/S

A circuit to allow the fan in the MFJ-4225MV (or other) power supply
to run only when needed, which quiets it down a lot.

Some mods to KD1JV Butterfly source for DDS

Steve Weber made his source code for the Atmel Butterfly demo board
available for users to modify.  I added the ability to toggle between the
AD9850 and AD9851 versions of the NJQRP DDS boards plus the
ability to use a rotary encoder for frequency control.

Crystal characterization and filter design

From a presentation I gave at OzarkCon in Joplin, Missouri in 2008

1-bit sine generation with a PIC MCU

Just for fun, generating a sine wave with an 8-pin PIC

2M FM Receiver with MC3362 chip

I've seen several articles making HF receivers out of FM receiver system
ICs.  I thought I'd try one as an FM receiver first.  My first iteration
uses the Si570 synthesizer controlled by Arduino as LO

My Ham Blog

Here's my ham blog.  Some enteries repeat stuff on this
page but a few are found only on the blog.

Squarer circuit for power measurement

Uses four matched transistors in a translinear circuit

2-tube homebrew QRP TX project

A 6CL6 / 5763 crystal controlled 5-watt transmitter

My 1929 Hartley Transmitter

Notes & schematic on my '29 design 2 watt transmitter

PHSNA Article in QQ Sprint 2014

Article on Poor Ham's Scalar Network Analyzer
Uses an Arduino and an AD8307 log power measurement IC
PDF 2.8 MB



An Excel spreadsheet that does ladder network analysis including crystal filters, and plots the response.  Based on a description by Wes Hayward in Introduction to RF Design.

Phasing RX PowerpointI discussed the design and construction of a phasing type receiver at OzarkCon 2016. My powerpoint slide show is linked at the left.

Like Morse Keys?
Check out my key page
Tiny Photo of J-38

My Morse Key Page