1.
Building the Minima
An Arduino based HF Transceiver
Thomas - KK6AHT
Pacificon 2014

2.
Licensed in 2012 at Pacificon
Extra license with K6BJ classes in Dec 2012

3.
Farhan aka VU2ESE
Author of the BITX20

4.
The Minima
Announced on January 16th 2014

5.
General coverage HF Receiver 0 to 30 Mhz
CW and SSB operation
Power output 5 watts (w/ amplifier)
LCD Display - Arduino controlled
Open Source Code
RIT and two VFOs
Super Heterodyne with IF at 20 Mhz
Cost under $100

6.
Arduino - LCD Display
Si570 XO (VFO+20Mhz)
CQ CQ …
14.285
KISS Mixer
Crystal Filter
20 Mhz
RX
Pre-amp
BFO
20 Mhz
Diode
Mixer
AF
Pre-amp
AF
Amp
34.285
CQ CQ …
20 Mhz
CQ CQ …
20 Mhz
CQ CQ …

7.
Arduino - LCD
Display
Si570 XO (VFO
+20Mhz)
KISS
Mixer
Crystal Filter
20 Mhz
RX
Pre-amp
BFO
20 Mhz Diode
Mixer
AF
Pre-amp AF
Amp

8.
Arduino - LCD Display
Si570 XO (VFO+20Mhz)
KISS Mixer
Crystal Filter
20 Mhz
TX
Pre-amp
BFO
20 Mhz
Diode
Mixer
Mic Amp
34.285
CQ CQ …
20 Mhz
CQ CQ …
14.285
CQ CQ …
20 Mhz
CQ CQ …
LPFs

9.
Arduino - LCD
Display
LPFs
Si570 XO (VFO
+20Mhz)
KISS
Mixer
Crystal Filter
20 Mhz
RX
Pre-amp
BFO
20 Mhz Diode
Mixer
AF
Pre-amp AF
Amp
Mic Amp
TX
Pre-amp
CW Tone
TX / RX
Serial Port

10.
Homebrewing the
Minima

11.
Measuring the crystal filter

12.
Measuring the crystal filter
• Converting Voltage into Power?
• Impedance of my signal generator?
• Impedance conversion?
• Termination?

13.
Measuring the crystal filter

14.
Reminds me of the roman army in the Asterix and the Roman Agent.!
- f

15.
Toroids …
• Do not be afraid
• Get a LCR meter (AADE - $100)
• Watch YouTube videos
• Get multi color magnetic wires for transformers

16.
Home made Arduino

17.
Home made Arduino
• Get a Atmega328P with an Arduino bootloader
• Or better, burn the bootloader yourself
• Enjoy the binary (works / does not work) aspects of
the controller board ;)
• If you are not familiar with Arduino, stick to the
standard setup for now

18.
Arduino - LCD
Display
Si570 XO (VFO
+20Mhz)
KISS
Mixer
Crystal Filter
20 Mhz
RX
Pre-amp
BFO
20 Mhz Diode
Mixer
AF
Pre-amp AF
Amp

19.
Receiving signals
• It is a lot easier than you think!
• Learnt how to debug amplifiers via transistor
biases, temperature and AC-coupled
measurements
• Built my first VXO and generating sine waves at 20
Mhz

20.
Finishing up
• Mixer fun: Carrier Suppression, Conversion Loss
and IIP3
• Output power, Harmonics and the FCC
• From 50mV to 50V

21.
Lessons learnt

22.
Blocks
• Learnt to see a circuit as blocks and stages
• Everything can be tested and measured independently
• Build, Test, Move on - Each stage is a project
• Keep a notebook - Take lots of notes

23.
Tools
• DVM, Scope
• Soldering Iron, MePads, Glue
• LCR Meter
• Some sort of signal generator
• BNC Connectors, 50 Ohm termination, Cables, etc
• Spectrum Analyzer or PHSNA is nice to have

24.
Reference
• Minima Initial Article
http://www.phonestack.com/farhan/minima.html
• Minima Mailing List
• And all the Minimas that have been built!
• Experimental Methods in RF Design (EMRFD)
• ARRL Handbook
• Chat With The Designer Podcast (cwtd.org)

25.
Solder Smoke
Bill Meara - N2CQR
Book
Blog
Podcast!!
http://soldersmoke.blogspot.com

26.
Closing Remarks

27.
Project Status
• Still actively being developed and designed
• The KISS Mixer will probably be replaced by
another mixer in the future
• This should not stop you!
!
• A few PCBs were made but distribution is limited
until the design is finalized
!
• You will need the RF386 Power Amplifier (or similar)

28.
Open Source Software
• Many contributions to the Minima software
https://github.com/afarhan/radiono
• WA0UWH leading the charge with WSPR support, CW
ID, Rotary encoder, etc
https://github.com/wa0uwh/radiono_erb

29.
Join the club!
Already 4 known Minimas in the
bay area.
!
!
Questions? Demo!!
!
!
Thomas - KK6AHT
http://sarfata.org/ham/minima
@sarfata
This presentation is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.