control & computing platform for
Micro908 News Blog
The Micro908 is an ideal computing platform for ham radio enthusiasts and homebrewing experimenters. Designed and developed over several years, this multi-use instrument serves as a common hardware platform for a growing list of powerful applications:
Latest Software: AA908 v6.0g and AF908
DM-908 News -- Start getting ready for the newest product software addition for your Micro908. The "DM-908" will serve as a digital modem allowing you to work PSK-31, QPSK, RTTY and other digital modes without a need for the PC. Just connect your SSB rig and a standard PS2-style keyboard to the Micro908, and you'll be ready to send and receive on the digital modes. More information is coming soon, but you can start by preparing the new front panel overlay for your Micro908 case, and making the simple keyboard connector mods on the Micro908 motherboard. (Note: The DSPx Daughtercard option is required for the DM-908 software to work in your Micro908.)
REFL -- Sneak peak at the new reflectometer and measurement sub-system for the Micro908 Antenna Analyst. It's still in development, yet initial tests look promising for providing a high-performance upgrade to the AA-908 capabilities.
Invaluable Utility Programs for the Micro908 ...
AF908 Overlay Graphic -- Are you looking for a modified overlay graphic that reflects the AF908 filter? If so, this PDF is file is for you! Just download it, print it, laminate it, cut out the holes and paste it place over the existing AA908 overlay. (In order to get the correctly-sized printout, be sure to select the "No Scaling" option in the printer control window.)
Flash Programming App Note -- Bob K7HBG found this informative application note on the Freescal website (suppliers of the 68HC908 processor we use as the heart of the Micro908) that describes very easy ways to create your own programmer for the HC908 Daughtercard. Homebrewers and software experimenters would want to do this to modify/customize their HC908 card bootloader, and other things. Further, he has a circuit diagram that explains what he has worked up to do his own bootloader re-programming and mods. Thanks for sharing this Bob!
Calibration & Accuracy Study -- Some Micro908 Antenna Analyst owners have been studying the slight measurement drifting and accuracy characteristics of the instrument. The drift is currently attributed to the heat generated by the DDS card affecting the reflectometer diodes, and the accuracy is somewhat affected by the limitations of 8-bit math computations and the inherent "uncertainty" of needing to simultaneously measure phase and magnitude of the reflectometer signals. Read all about it inside, including some photos and software improvements that are in progress.
AF-908 Debugging Guide -- Having trouble getting your DSPx card working with your Micro909 AF-908? Well, here are some debugging tips from Steve Holton, N1NB, who is the guy who wrote the DSP Audio Filter control program for the Micro908.
Backlight Control for LCD -- Here's a simple modification that will greatly increase the usability of your Micro908 instrument in low-light conditions.
DDS Amp-- The DDS Amp is a small "granddaughtercard" that sits on the DDS Daughtercard in place of the original MMIC amplifier. It provides superior signal quality and level adjustabililty that enables great calibration and measurement results. All Micro908 kit owners received the DDS Amp free of charge in the "Service Pack 2" mailing in March 2005. The Micro908 is now being shipped standard with the DD-60 Daughtercard, which has the amplifier built-in.
Manuals & References:
Micro908 Enclosure Resources -- Here are some files that will be helpful if you are building your own custom enclosure or labels. These file should be perfect for those wishing to design custom label panels for the AA908, or any other Micro908 project coming along.
MAV-11 Orientation -- If your DDS Daughtercard has a MAV-11 device for the final RF amplifier, please note the correct orientation for the "dot" for the output pin as being oriented downward on the pcb. See the photo.
Description -- This link provides a good overview of the kit and its capabilities. Includes block diagram.
Builders Notes -- A collection of construction Tips and Technique, and various Errata for the kit. This web page is important to see if you are currently building your Micro908 Kit.
Service Pack -- (for round 1 kit owners only) We've determined several optimizations that substantially improve usability and accuracy of the instrument. These optimizations consist of a small handful of replacement components that owners should install on their circuit boards, and a new software release that takes advantage of the optimized hardware.
Kit News -- Latest information about the kit: Round 1of the Micro908 Antenna Analyst started shipping at the end of September. More news inside.
FAQ -- Frequently Asked Questions ... and answers!
Prototype Photo Gallery -- A collection of views inside and around early versions of the kit.
Yahoo Group -- We maintain a
Yahoo Group discussion list for owners to post Q&A about the Micro908 kit. (We'll also
answer any questions posted privately or on QRP-L.) Click the
link above to address a new message to the Micro908 list.
A feature-length article concerning the Micro908 and the Antenna Analyst was in the issue #2 of HOMEBREWER Magazine
"Antenna Analyst AA-908"
Several years ago, N2APB and N2CX embarked on a journey to develop a low-cost antenna analyzer that would sweep the ham bands with a micro power transmitter and measure the resultant SWR of an antenna system. We presented the original design of the Analyzer at various QRP forums circa 1998-2000 and evolved the hardware platform several more times in the Digital QRP Homebrewing column of QQ magazine (proto 2 and proto 3).
The hardware design is complete and is now called the Micro908. It is a production-quality kit and has been available from the AmQRP Club since August 2004.
Micro908 is the common hardware platform
for many projects coming from
the AmQRP design teams."
What this means is that you get the Micro908 Kit, load it with FREE SOFTWARE that is downloadable from the AmQRP web pages, and you have a brand new instrument or radio accessory. Because the Micro908 is based on the NJQRP "HC908 Daughtercard" module, you don't need any special hardware or cable to load new software into the unit. You just connect the Micro908 up to your PC with a standard serial cable and send a new software program to the device.
The Micro908 is a flexible and re-usable control platform for ham radio projects. The Micro908 platform is designed to be easily operated on the bench as well as in hand while portable. It is comprised of a single 5” x 5” printed circuit board containing all components, connectors, controls, a 2x16 character LCD, and three daughtercards. The 5.5” x 7” x 1.5” plastic enclosure is also large enough to hold an 8-cell AA battery back enabling convenient field use. A number of standard ham radio peripherals may be connected to the Micro908. You can plug in an antenna, paddles, a PC-style keyboard, headphones, an audio line to drive an SSB transceiver, a keyline to drive a transmitter, your rig's audio in/out signals, and custom control lines via an auxiliary jack.
- 1.2.HC908 Daughtercard – fast, flexible, self-programming microcontroller with lots of I/O and FLASH memory
- 3.Low power DDS Daughercard provides 0-30 MHz signal source & stable VFO
- 4.Reflectometer designed for low power measurement accuracy of SWR and complex impedance
- 5.LCD, pushbuttons & encoder for effective programmable user interface
- Optional graphic LCD directly displays SWR & frequency graphs (future capability)
- 6.Audio amp & speaker for “eyes free” operation & reporting
- 7.KK7P "DSPx" Daughtercard for powerful signal processing - same as used in Elecraft K2 and TAPR DSP-10
- 8.Aux connector provides keyline + custom signal I/O
- Standard PC keyboard plug in for convenient user input as digital mode controller
- Low cost portable keyboard available as accessory
- Key/Paddle input for use as powerful memory keyer
- 9.Battery operation for convenient field use -- 12V input for bench use
- 5" x 5" pc board holds all components, daughtercards and controls
- PC board designed to fit into convenient ABS plastic enclosure from PacTec
- Templates provided for custom front panel labels
- 10.Serial port to PC for optional processing & display of results
- "PC Link" program on the PC plots SWR, stores data and remotely controls the unit
- 11.“Open design” – hardware & source code freely available via GNU Public License
A complete Micro908 motherboard assembly
Shown without the enclosure and including the optional DSPx daughtercard (lower right)
The Micro908 is built around three modular daughtercards available within the homebrewing community:
(1) The HC908 Daughtercard plugs in as the main computing engine for the platform and provides flexible programming, field updates, powerful processing and a multitude of input/output lines for controlling all the devices in the unit.
HC908 Daugtercard -- main control unit for the Micro908
(2) The NJQRP DDS Daughtercard serves as a precise and accurate signal source that is programmable by the HC908. This plug-in module gives the Micro908 platform the ability to serve as an audio and RF signal source for testing and network analysis.
DDS Daughtercard -- programmable RF signal source for the Micro908
(3) The KK7P DSPx Daughtercard is an optional module that gives the Micro908 platform a powerful signal processing capability suitable for serving as a digital modem for PSK31, PACTOR and other digital modes of operation. This is the same DSP module as optionally used in the Elecraft K2 HF Transceiver as an audio filter, and in the DSP-10 software defined radio project from TAPR. When coupled with the HC908 controller, the DSPx daughtercard makes a formidable portable computing platform.
KK7P DSPx Daughtercard -- provides powerhouse signal processing for advanced audio features in the Micro908
Block Diagram of the Micro908
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Page last updated: April 2011