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
