The concept started several years ago when I was searching to see if I could find one of the Mizuho MX SSB/CW HF transceivers. I started thinking about repackaging an existing QRP SSB transceiver design with a digital synthesizer.
...and that initial idea was abandoned when I started working for a start up and it took all of my time away from projects in general.
in 2007 I restarted the concept after a phone conversation with my dad ~ he was asking me about the cost-to-cost walkie talkies cell phones. He said "...sounds a lot like ham radio to me!" so i began thinking of a new concept. and worked on it until 2009. I switched to build a couple of tube projects, to rest my eyes and just to have some fun!
I have begun recovering the old project files and posting them on this new blog.
Here is the chronology of this project:
1996 - While working at RF Microsystrems on a commercial receiver design project, I discover and use a AD9854 from Analog Devices Inc DDS chip for my design - very tiny but easy to use.
1997 - I see an article in QEX July 97, with the same series AD9850 DDS.
1998 - Order two boards from Far Circuits for the article in QEX, get a couple chips as samples from Analog Devices and one of the bench techs at work even solders the small chips on these for me! Thought they may be useful for ham radio someday. Rewrite program for PIC16F84.
1999 - 2000 Order a Small Wonder Labs WM-20 20M SSB transceiver kit - (no longer available) I actully wanted just to "kit bash" for parts to test with DDS as VFO, ended up building DDS/SSB QRP radio into a 1U 19" rack enclosure ...This was actually the 1st, if not so hand hold-able prototype!
2001 - 2006 Again, work interrupts all HAM radio project development!
2007 - Revive the concept. Come up with a form factor that looks promising. Begin hand built several protos:
(X0) dead bug for first PCB prototype, it worked OK but did not fit in case and wrapped on both sides.
(X1) The initial PCB did not work very well, the gains were bad and I thought layout was the problem.
2008 -
(X2) Began full scale RF board proto that would fit in chassis, proto DDS with PIC and external DDS-60 kit. Built proto DDS board and RF PA. Some layout issues but both work fine. Develop the PIC software (V1.0 was hard coded to 20M band but have plans to make it configurable)Proto became too hard to modify, lots of hot melt was holding it together!
2009 -
(X3) Second PCB with all of the changes form the X2 experiments went into a second PCB, the initial results were disappointing, low gain on RX. The root cause was the switch pattern I made for X1! One circuit crossed in the pin out, this may have actually been the main problem in X1 as well. Spent almost a month tracking the issue and bringing up the board. Fixed with a simple cut and jump under the switch and the PCB works as well as the protoboard.
Transmitter testing started, got the IF and tested the PA. The one circuit I wished I had was a test oscillator/cw generator. Built a second case.
The project was interrupted by Paraset! I got tired of FIXING all my design issues and small parts! (needed a microscope to build the synthesisers board) Just wanted to reproduce a simple radio. (now also working on Mk-III but that is another story)
TO DO LIST:
- Complete RF testing on the TX side
- RX Noise issues from CPU and LCD
- Complete multi band firmware
- UPDATE PCBs
Updates final proto PCBs:
- RF PA - need better RF detectorfor meter and pre-driver layout, may add test circuits (sig gen)
- DDS/CONTROLLER - Fix crossed LCD signals and final OP amp circuits. Add MIC and Voltage adjust to the board (makes panel layout and wiring easier) Delete external DDS connector (no longer needed) May put a better PIC, add a 2nd PIC as a RTY/CW gen/decoder/RTC/ + Serial (USB?) interface. Better shielding/RF bypass/voltage regulators.
- IF/RF BOARD - May change to electronic switching. Simplify RF/AF path as well. It would be a major revision. Also may use more SMT and possibly put the DDS chip on this board.
NOTES/REFERENCES:
- Small Wonder Labs WM-20 SSB Transceiver Kit, by Dave Benson, K1SWL: – NLA “These are items where slow sales/high restock costs, or other factors have made it impractical to offer them at present….” http://www.smallwonderlabs.com/
- Building a Direct Digital Synthesis VFO, by Curtis W. Preuss, WB2V QEX July 1997
- The Mizuho MX SSB/CW HF series handhelds were actually produced from 1983 until 2002, a total of 19 years, making them probably longest on the market of any ham transceivers ever produced. The last ones produced in 2002 sold out quickly and probably will never be anymore made as many parts are simply no longer available. http://www.mizuhoradio.com/mx.html
- Oh yeah, I also have since changed the name from M610, it’s kind of a configuration nightmare but since this version will never be reproduced it should not be too confusing, but if you see any references to that model this is why. I'm thinking an FM –only design for 10 and 6 Meters…
- AMQRP VFO-60 Kit http://www.amqrp.org/kits/dds60/
- 75 Meter Transceiver Project, by David Forsman, WA7JHZ, http://www.qrp.pops.net/Idaho.asp
- BITX20 by Ashar Farhan VU3ICQ, http://www.phonestack.com/farhan/bitx.html
- A Simple Dual Band SSB Transceiver by Ashar Farhan VU3ICQ http://www.phonestack.com/farhan/xcvr1.html
- Simple Sideband, Another Approach, by David Harrison, W6IBC QST November 2007.
- MMR-40 Transceiver by Steven Weber, KD1JV QST Aug 2008 p33-36
- TAK 40 Transceiver by Jim Veatch, WA2EU, QST May 2008 p33-37
- an FM only version for 6 and 10 meters will be called the M610
- Low power SSB band plans: http://www.hfpack.com/air/
- Lakeview Company, http://www.hamstick.com/
- While researching this I found this project on the QST archive… A Transistorized Handi- Talkie, 28-Mc. Hand Carried Station for Short Range Communications, By William J. Engle, Jr., W3KKO, QST Feb 1960 p20-22
Sources:
