BULLETIN:     SD1001
VENDOR:       STANDARD  C-500
SUBJECT:      EXTENDED RECEIVE/TRANSMIT RANGE


AS WITH ANY MOD, DISASTERS YOU MAY HAVE ARE NOT MY FAULT. UNDERTAKE IT AT YOUR
OWN RISK ! The procedure will erase all your memory settings.

Remove the AA batteries.  Remove the 4 screws through the metal back panel (it
is not necessary to remove the belt clip) and pull the back panel away from the
front.  The volume control, tuning knob, and antenna stay attached to the back.

The battery compartment stays attached to the front.  Be careful as there is
wiring betwwen the two halves.  (It is not necessary for the modification, but
if desired, the flexible cable can be disconnected by lifting the ends of the
white retainer clip at either connector, then pulling the cable out of the
connector.  Reattach the cable by placing it in the connector, then pressing
the retainer clip back down.  These connectors work like "zero insertion force"
sockets.)

Locate the lithium battery, which is on the front circuit board.  Unsolder the
(-) lead of the battery from the circuit board and fold the battery up away
from the board on the (+) lead.  Note that there is a block of sticky foam
under the battery which needs to be unstuck.

Having the battery out of the way, locate the 3 option jumpers beside and to
the right (as you look into the back) of the microprocessor chip, on the area
of circuit board that was under the battery. There should be places for 3, but
only the bottom one has a jumper (a tiny green part which is a zero-ohm surface
mount resistor).  See diagram below.  The out of band transmit jumper is "C".
Remove that jumper.  The easisest way to do this is to use a soldering iron with
tip large enough to touch both ends at once, melt the solder and push the jumper
to the side and lift it away.  The mod can be undone later with a piece of fine
wire.
C508 Jumpers:

                                   * *   (These 2 are far removed from the
                                   D E    others, near the edge of the board)
                                   * *
                  *A*
                  *B*
           CPU    *C*
              ___
                   *
                   F
                   *
Jumper  Function
A        ?
B        Closed: Europe ham bands (open at factory for US model)
C        Closed: Transmit only in ham bands (closed at factory)
D        Closed: Tune only in ham bands (no out-band receive)
E        Closed: Lock out cellular band (closed at factory)
F        Closed: 440/1296 model (different RF board req'd apparently)

Put the battery back down and solder the (-) lead back on.  Then reassemble the
radio.  Before putting the AA batteries back in, press the reset button.
Should come up in VFO mode at 446.0 MHz.
Transmit coverage is approximately 115-162 MHz and 400-460 MHz, depending on
the temperature, voltage, etc.  Near the high end of the out-bands, Tx audio
may be poor.  Operation only inside amateur bands is strongly recommended.