Design Goals:

- Station Control and Logging either at home or on the road.

- Fast, modern computer with full compliment of serial, USB, and Ethernet ports.

- 12-Volt vehicle or station supply operation.

- Dashboard mount display.

- Miniature keyboard and touchscreen suitable for mobile use.

- Global Positioning System.

- Voice control and feedback.

- Off-the-shelf, easily obtainable components and software.

Details:

The computer is built around an efficient, low-heat, mini-ITX motherboard with a Via C3 E-series processor running at 1Ghz. I chose 512Mb main memory and an 80Gb low-noise disk drive. The back panel contains four serial ports, four USB2.0 ports, two 100Mb/sec Ethernet ports, VGA connector, PS2 keyboard, mouse, printer port, and soundcard connectors. Packaging is an Elecraft EC2 case with bail. Externally connected is a seven-inch LCD touchscreen display and a full-function super-mini keyboard. Full specifications can be found at http://www.viaembedded.com/product/epia_cl_spec.jsp?motherboardId=181

An Andrea ANC-700 noise-canceling microphone USB microphone is used for voice command.

The operating system is Windows 2000 Professional.

Power System:

The power subsystem consists of two printed circuit boards; a 7-amp 12-volt regulator/sequencer and an 80-watt computer power supply. The regulator is mounted on the EC2 right side panel and the power supply is mounted on the front panel. Approximately three amps are required.

Power is provided by the vehicle electrical system or station power supply. The raw unswitched power is input through an Anderson Powerpole connector on the rear panel to the regulator/sequencer board. A switched voltage is connected from a source (such as the FM radio power lead) to a coaxial power jack mounted on the rear panel. This sense voltage is continually monitored by the microprocessor. Based on the state of the sense line, the sequencer outputs regulated 12V the computer's main supply and acts as a power switch via the power switch connector on the motherboard.

On vehicle start, the sequencer delays three to four seconds after sense line goes high, then applies the regulator's output to the power supply. After a one second delay, it then momentarily shorts the power switch connector on the motherboard placing the computer in the power up state.

Vehicle shutdown drops the voltage on the sense line. After a five second delay, the sequencer again shorts the motherboard's switch connector to signal shutdown, but maintains regulated power to the computer power supply for another 45 seconds. The computer enters an orderly shutdown state, closing open programs and properly terminating the operating system. If your system hangs during shutdown, power will be shut down hard, turning off the main power source to prevent battery drain.

Block Diagram of the ITS Power Regulator/Sequencer
 

In a home station environment, the sense line is impractical. To overcome this, I added a front panel switch that simply applies the sense voltage to the sequencer from the positive input line of the station power supply. This switched line and the mobile sense line connector are isolated from each other by blocking diodes. When used in this manner, turn on the station supply then toggle the front panel power switch ON. This switch should be OFF for vehicular use of the sense line. Also, applicable only to the home station, a second switch is provided on the front panel to disable the internal regulator. Since vehicle voltage can spike 18-20V, this switch should be turned on at all times when mobile. When on, the regulator board can supply 7-amp, and 20-amp when off.

The mainboard power supply is rated for 80-watt dc-dc converter with 12-30-volt input. The output connector is a standard ATX female connector. An extension cable is used to connect the

Mainboard:

The ultra-compact and highly integrated VIA EPIA-CL Mini-ITX mainboard was selected based on processor speed and full array of I/O ports, and of course, it's size. The Mini-ITX form factor is the smallest available today, and is the only one that will fit into an EC2. It measures a scant 17x17cm. The model I selected boasts of 128Kb L1 and 64Kb L2 caches, and one DDR266 memory slot holding up to 1Gb, and a 1Ghz processor. AGP graphics, stereo AC'97 codecs, USB 2.0, 100Mb ethernet, serial ports, and 66/100/133Mhz UltraDMA IDE support is also present. The Award flash BIOS is updateable over the Internet.

The User's manual is complete, giving location and pinouts of every connector. It also describes the BIOS option quite well. A CD-ROM is included which contains easily installed drivers for VGA, Audio, LAN, USB 2.0, and FIR (infrared).

This computer is not a powerhouse – don't expect Pentium4 performance – but it does at least as well as my 700Mhz Athalon-powered machine. I have not found any software incompatibilities. I have tested the K2MC with Suse 9.0, Slackware 9, and Windows 2000 Professional. It runs them all equally well.

Disk Drive:

I chose a Seagate Barracuda 80Gb 7200-rpm 3-1/2" drive because of its industry leading low-noise rating. This drive has excellent performance characteristics. Other disk drives are also suitable and are the builder's choice. How about one of the miniscule IDE drives from a laptop? Adapter cables are available that make such a substitution possible.

Cooling:

The mainboard contains a small heatsink with a quiet fan for CPU cooling. There are two other passive heatsinks to cool certain large-scale integrated circuits. If this mainboard were mounted in an adequately ventilated cabinet that would be all that is required for proper operation. When mounted in an EC2, an additional cabinet fan is required. At first I chose a 6-CFM 40x40x10mm low-noise fan. This fan performed adequately, with the cabinet becoming only slightly warm after extended use. When I started using the K2MC in my pickup in the hot summer sun of Louisiana, I decided to change the fan to a 60x60x15mm fan with an 18-CFM rating. With this fan, the cabinet stays as cool. The drawback to this larger fan is more noise. If low noise is important to you, stick with the 40x40x10mm fan. Air is drawn into the case by the fan through a replaceable dust filter, and exhausts through the read panel. The CPU temperature stays around 40 degrees C, well within the manufacturer specifications.

The disk drive is cooled by mounting it flat against the EC2 bottom panel and uses it as a heatsink. Combined with the case fan, the drive runs perfectly cool.

Metalwork:

With no training or experience in this art, this was the hardest part of the project for me. I dry-fitted parts over and over again until I was satisfied that everything would fit. There is a lot of hardware inside and not much room for error. My final arrangement was to mount the mainboard on the top panel, the disk drive on the front portion bottom panel, the regulator on the right side, the fan on the left side, and the power supply on the front panel. Air circulation concerns were the dominant factor in these placement decisions.

Tools used were a Dremel tool with cut-off wheels, a flat single-cut file, a half-round double-cut file, assorted drill bits and electric drill, and a 6-inch metal scale. A sharpened nail was pressed into service as a scribe. The most valuable drill bit I own is a Unibit. Get one – you will thank me later.

The rear portion of the top panel was cut first. Attach four ¼" metal standoffs to the motherboard. Turn the panel upside down and place the mainboard side-to-side and press the connectors up against the back panel. Scribe a line on the inside of the rear panel using the outside edges of the PS2 connector tower and the Audio connector tower as a guide. Measure down 30mm from the edge of the back panel in two places and scribe a horizontal line to complete the outline of the cutout. Use the Dremel tool with cutoff wheel to cut out the panel slot. Cut only to within 1mm of your scribed lines. Use your flat file to file the slot to the final dimensions. With the case assembled, and viewing it from the rear, the final dimensions of my cutout are:
Left vertical cut is 27mmm from the left edge.
Right vertical cut is 23mm from the right edge.
Horizontal cut is 31mm from the bottom edge.
Horizontal cut is 9mm from the top 90-degree bend.

The Audio connector tower is a little taller, and will not fit the rear panel cutout at this time. An additional slot must be cut in the rear panel of the bottom panel. This slot should be as wide as an Anderson Powerpole connector pair, and should be 10mm deep. The Powerpole has a small notch on either side. The slot is cut so that it fits into these notches to hold the connector in place. When the case is assembled, the top of the Audio connector tower will hold the Powerpole in place. My final dimensions of my cutout are:
Left vertical cut is 26mm from the left edge.
Right vertical cut is 40mm from the left edge.
Horizontal cut is 16mm from the top edge.

The power supply was mounted to the front cover on two ¼" x 4x40 threaded metal standoffs. Position the supply on the right side of the panel as viewed from the front spaced a distance of 10mm from the side panel. This leaves approximately 80mm of blank panel on the left side for switches and lamps. Orient the power supply so that the large power connector is near the side panel, away from the mainboard power connector. This leaves sufficient room to route the cable to the mainboard. Use black Elecraft cabinet screws through the front panel, and what-have-you through the circuit board.

The regulator is mounted on the right side panel with the heatsink facing the front. It is positioned so that the notch between the nylon power connector and the heatsink is centered over the mainboard memory slot. This leaves room to insert the memory board without removing the regulator. Use two ¼" 4-40 nylon standoffs with black cabinet screws through the panel and nylon screws through the circuit board. This board must float from cabinet ground.

The mainboard is mounted on the top cover on four ¼" metal standoffs. The rear panel connectors should fit perfectly in the cutout. If not, file the cutout to required size.

The disk drive is mounted on the bottom panel centered side-to-side. The connectors face the front panel, and the drive is mounted 25mm from the front edge of the panel. The rear of the drive extends 45mm past the panel edge. Make a paper template of the drive's mounting hole layout and transfer to the panel. Mount the drive flush against the panel with four screws. The disk drive cable is 18" long and has three connectors, while we require a 6" cable with two connectors. With a razor blade, cut off the longest span of cable and its end connector. Lay the cable on a flat work surface and draw the blade along the side of the middle connector. It cuts easily.

Three miniature toggle switches on the front panel for power, regulator bypass, and computer reset. These switches were color-coded with plastic sleeves designed for this purpose. Position the first switch 20mm from the left side panel and 20mm from the bottom edge of the front panel. Spaced them 20mm apart. I used individual pins from a .010 pc-mount header strip and soldered them to the switch lugs. By carefully bending them to .010" spacing, they can be connected to by standard 2-conductor plugs such as salvaged from the case wiring harness of an old desktop PC.

Three LED panel mount displays were mounted 25mm above each switch. I color-matched the lenses to the switches. The green LED indicates power applied to the mainboard. The yellow LED indicates CPU sleep mode, and the red LED indicates disk activity. I used white, ultrabrite LED for the indicators. The green indicator appears blue when lit, so you may want to consider using a green LED for this indicator. Also, the ultrabrite LED's I used produce a very bright light. Although the lens diffuses it, it may be too bright for some. The indicators I chose have a wide 170-degree field of view, an important consideration.

The fan is mounted on the left side panel, with the forward edge 45mm from the front panel and centered top to bottom. I scribed a 20mm diameter circle using the rounded edges of the fan for a guide. Using my Unibit, I cut a series of circles with the outer rims about 3mm inside the scribe marks. I then used the Dremel with a cutoff wheel to remove all metal to within 1mm of the scribed circle. Judicious use of the half-round file finished the job, resulting in a near perfect circle. The fan is mounted inside the case with the filter bezel on the outside.

The lower rear panel contains three DB9M serial connectors. When I attempted to make the cutouts for these connectors, I really messed up. I used the rear-panel insert that comes with the mainboard as a template to make the cutouts, only to discover (much to my embarrassment) the DB9M connector could not be secured in the hole. You can always make a hole larger, but not smaller! To rectify my problem, I used the piece cut out when preparing the mainboard rear connector cutout as a plate in which to mount the connectors. This time all went well and the connectors mounted well. To make these cutouts, I scribed a rectangle for each connector, spaced 34mm on center. Again using the Dremel tool, I cut the slots and filed smooth. I used the Dremel to cut a slit on both the left and right of each square to allow for the DB9M mounting screws. I then cut the original back panel (the one with the oops!) to allow the connector plate to be attached with four cabinet screws and nuts.

You will find that DB9M connector assemblies will not fit into the case in their original configuration. There is a black plastic cable guard molded to each connector that protrudes too far. Carefully remove these guards without damaging the ribbon cable by splitting it lengthwise with a pair of wire cutters.

The DM9M connectors can be purchased in two configurations. One is cross-wired and the other is straight through. For some reason, the cross-wired is much cheaper than the other. Purchase the cheap ones and rewire them to the straight configuration. Also, shorten the cables to four inches.

Mount a coaxial power connector on the upper rear panel in any convenient spot. This connector will serve as the ignition sense line input. If desired, mount a second coaxial power connector for use as auxiliary power for an accessory

Prepare the EC2 case by sanding off the coating where the cabinet touches a 3-D connector. This maintains electrical bonding of the various panels. This is necessary because power supply, the mainboard, and the disk drive share a common return.

Peripherals:

Any VGA monitor can be used at home, as well as a full-size keyboard and mouse. In the mobile environment, however, miniature devices are the rule. The VGA display I use is a 7" touchscreen LCD display with a maximum resolution of 1024x768. I use 800x600 resolution for easier viewing. The touchscreen eliminates the need for a mouse, although a stylus must be used instead of you finger for some software. The buttons are just too small.

The super miniature USB keyboard is only 20mm wider than the EC2 with keys large enough to be useful. It is laid out much like a laptop keyboard, and is perfect for mobile use.

Use:

Voice control and feedback is a work in progress. I am currently using it with DeLorme Street Atlas 2004 software and an Earthmate GPS receiver with excellent results. The selection of the ANC-700 USB microphone was a wise choice, since I can command the map display with the radio blaring and the window rolled down. I am experimenting with commercial computer voice control software to see if I can entice HRD or DX4WIN to control my K2 station.

Computer performance has been quite satisfactory. It is not a Pentium 4, but I am able to run processor-intensive continuous voice recognition, HRD, DX4WIN, Spectrogram, and Street Atlas simultaneously with excellent reserve memory capacity and processing speed.

Although not yet fully characterized in a RF environment, preliminary testing has not uncovered any problems at the 100-Watt level with my K2. No computer-generated EMI has been noted. No special precautions have been taken to filter cable egress points, although ferrite cores are on the K2 serial cable harness to the KAT100, KRC2 and the K2MC. Remaining to be tested is the performance at legal-limit power, and full characterization of birdies.

I may be contacted at k5jaz@arrl.net if you need more information while building your own K2MC.

Regards,
Jim Brown, K5JAZ




Bill of Materials:

Mouser Electronics, http://www.mouser.com

1x 664-D4006MX-12V ADDA DC Fans 40mm 12VDC 5.2CFM
1x 562-09150F30 30 PPI FLTR ASSEMBLY
Or
1x 670-OD601512HB 60mm 12VDC 17CFM Orion DC Fan
1x 670-GRM60-45 45PPI FLTR ASSEMBLY Orion Fan Accessories

6x 538-50-57-9002 NONPOLARIZED HDR 2P for Molex SL Connectors
12x 538-16-02-1114 Female High Force Molex SL Connectors

2x 163-4020 Kobiconn 2.1mm DC Power Jacks
2x 1710-2131 Kobiconn 2.1mm DC Power Plugs

2x 10TC220 Mountain Switch Miniature Toggle Switches 2 SLDR TAB SPST BLU
1x 10TC232 Mountain Switch Miniature Toggle Switches MS500B STD LVR
10TB001 Mountain Switch Miniature Toggle Switch RED PLASTIC CAP
10TB005 Mountain Switch Miniature Toggle Switch YELLOW PLASTIC CAP
10TB006 Mountain Switch Miniature Toggle Switch GEERN PLASTIC CAP

1x 593-3210R VCC LED Lens Mounts 5MM LOW PROFILE RED LENS
1x 593-3210G VCC LED Lens Mounts 5MM LOW PROFILE GRN LENS
1x 593-3210Y VCC LED Lens Mounts 5MM LOW PROFILE YEL LENS
3x 593-SPC060 VCC LED Hardware Spacer
3x 593-CNXCE2108 VCC LED Cable Assembly 5MM PNL/.025" HDR 8"


4x 561G440 4-40 Hex Nuts
4x 561-P440.375 4-40x3/8 screws
4x 561-P440.5 4-40x1/2 screws

Elecraft, http://www.elecraft.com

1x CHSCRKT Chassis Screws, Black, 4-40 x 3/16" Pan Head (qty 20 per package)
2x E620032 2.1mm Power Plug (also under Mouser)
1x APPCON Anderson Power Pole 30A Connector (Red/Black) for K2/100
1x EC2 Blank Project Enclosure
1x ETS15 1.5" Tilt Stand for EC2, KAT100 or 1x ETS2 Std 3" Tilt Stand for EC2

Logic Supply http://www.logicsupply.com
1x VIA CL1000 Mainboard http://www.logicsupply.com/product_info.php/cPath/21/products_id/140
1x ITPS Power Sequencer and Dropout Regulator http://www.logicsupply.com/default.php/cPath/40
1x PW-80 dc-dc Power Board, 80W
http://www.logicsupply.com/product_info.php/cPath/40/products_id/204
1x ATX Power Supply Extension Cable
http://www.logicsupply.com/product_info.php/cPath/40/products_id/204
1x 619GL-70NP TFT LCD Display
http://www.logicsupply.com/product_info.php/cPath/52/products_id/193

Directron http://www.directron.com
1x HD-S-80-7 Seagate ST380011A 80GB drive http://www.directron.com/sea807200.html
1x Super Mini Keyboard http://www.directron.com/psk3100u.html
1x CBL-IDE-100 HD cable http://www.directron.com/ata100cable.html

CablesToGo http://www.cablestogo.com/
3x 02882 DB9M Serial Add-A-Port Adapter 11"
http://www.cablestogo.com/product.asp?cat%5Fid=908&sku=02882
Please note: This is the crossed-configuration cable. The plastic cable shell must be removed and the
connector must be rewired for straight-through operation.

EMicrophones http://www.emicrophones.com
1x Andrea ANC-700 headset http://www.emicrophones.com/microphones/product_detail2.asp?mfgID=3
1x Andrea USB pod http://www.emicrophones.com/microphones/product_detail2.asp?mfgID=3