MiniSport Laptop Hacker - Vol #23. September 1994 To discourage pecuniary interests, Copyright (c) 1994 Brian Mork >>> ADMIN The MLHacker series is formatted to print out on 8.5"x11" sheets manually fed into an Epson LQ-850. I print at 8 lpi, which gives 82 lines per page. Back issues are available from ftp.cs.buffalo.edu in the \pub\msdos\ham-radio directory. They are also available in the SimTel archives (e.g. oak.oakland.edu//pub/msdos/packet/mlhacker.zip). >>> MOBILE BATTERY POWER Last issue, Jim Harvey contributed details of how to wire up a Makita power drill's battery pack to the Minisport. In this issue, is part one of how he describes making a suitable container for the batter pack, without scavenging the handle of the drill! "In the February 1994 issue of WORLDRADIO, Gary Magnum W6WWW described the use of a Makita tool battery for powering his HT. There are many advantages. A Makita battery has several times the capacity of a large HT pack and they can be purchased for $30 to $40. Makita packs come in 7.2 and 9.6 volt versions and the DC 9700 fast charger (about $50) handles both types. "Gary used the broken off handle from a Makita tool to hold his battery. I had been contemplating using my two Makita batteries for Ham Radio purposes but was unwilling to mutilate my $150 drill to do it. My solution was to construct a fiberglass cap containing contacts for the business end of the battery. The cap fits snugly and a depleted unit is easily changed. One 9.6 volt pack will run the receiver on my ICOM IC- 02AT for about a day. My goal is a complete portable packet station with TNC, Laptop, and HT all energized by power tool batteries. "There are other tool brands featuring removable battery packs which may be adapted with a little engineering. CamCorders also use packs that may be adapted to portable radio service with a similar contact arrangement. "To construct a similar cap, begin by making a contact header that fits over the top of the pack. Then cover the header, wires, and 2 - 3 inches of the battery with a layer of fiberglass. You will end with a light, sturdy assembly that is hardly larger than the battery pack itself. The whole thing can be tucked into any convenient pocket. Before you begin, please note that a fully charged power tool battery can deliver over 50 amps into a short circuit. This is enough to melt wires and possibly cause a fire. Be VERY careful. "Here's a list of materials you will need: Piece of single sided glass Epoxy PC board material, 1" by 2". Strip of brass for contacts .025 to .035 inch thick, 1/2" wide, about 2" long (check hobby shops). Fiberglass cloth and Epoxy resin. I used Bondo brand from an auto supply store. Power cable with inline fuse holder and connector for your radio. "Tools: Scissors Tin Snips Flat file or hand nibbler Fine sandpaper Thin string 3 or 5 ounce Dixie cup to mix Epoxy Sacrificial small 1/2" or 1" paintbrush for Epoxy Rubber gloves for working with Epoxy Cheap Condom "Begin by constructing the contact header assembly. The first step is to remove a strip of copper from the center of the PC board with a file, hacksaw, or knife. Remove at least 1/16" of copper. Remember these battery packs can deliver a huge amount of current so you must be sure there is no possibility of a short circuit between the two halves. Place the PC board material on top of the battery pack and trace the outline on the board. Cut and file the board to match the battery. I've found the easiest way to cut glass Epoxy PC board material is with large tin snips or a hand nibbling tool. Mark and file two notches in the long edges of the board to match the recessed terminals of the battery. Single Sided PC Board Header Cut to Fit Top of Battery Notch for battery contact | ----------- v ----------- -------- / |-----| \ | / \ | / \ | Insulating cut --> |===================================| 1 inch down centerline \ / | \ / | Round corners \ |-----| / | to match battery | ----------- ^ ----------- | ----- top shape | | | | Notch for battery contact | | | |<<---------- 1 7/8 inches -------->>| "Next, cut two "T" shaped contacts from the strip of brass. The horizontal part of the "T" will be soldered to the PC board header and the vertical stem will be bent down 90 degrees to form the actual contacts on the battery terminals. File these smooth, then flatten and bend as shown below. |<<------ 1/2 inch ------ >>| | | ______________________________ _____ Brass | | | contact | | 1/4 before | | in. bending | | | |________ _bend_line_ _________| ___|_ | | | Trim or file | | | both sides | | | | 1/2 to fit | | in. battery | | | | | terminals | | | | | | | | |______________| ___________|_ | | 1 " | | 1 " | |< - >|<<-- 1/4"-->> |< - >| | 8 | | 8 | _____________________________ / this part soldered / / to header PC board / / / /____________________________/ \ \ Bend tail of \ this part \ brass contact \ contacts \ down 90 degrees \ battery \ \ \ \______________\ That's it for this issue. Next issue will finish the construction project and then we'll get back to normal. Did you see the July QEX article about using the Minisport and an Optoelectronics M1? Next issue, I hope to have details about converting the modem port to a standard COM2: serial port using the board shown in Photo 2 of that article. Please provide feedback! * Direct data 1-509-244-9260 * ARO Net KA9SNF@ka7fvv.#ewa.wa.usa * Internet bmork@opus-ovh.spk.wa.us 73, Brian * 6006-B Eaker, Fairchild, WA 99011