R7000.8

                      198 CHANNELS FOR YOUR
                         R7000 RECEIVER?

                      by Bob Parnass, AJ9S

     The ICOM R7000 appears to use a uPD446C, 16K static RAM
     chip,  for  storing  99 memory channels.  By looking at
     the pinout of this chip (IC8 on the Logic Unit)  in  my
     service  manual, it appears that ICOM is only using 1/2
     its memory capacity.  Address lead A10 (pin 19) is sol-
     dered to a ground pad.

     To double the number of memory channels in the R7000 to
     198,  it looks like one could "lift" pin 19 of IC8, and
     connect it to pin 24 (+Vcc) through a 10,000 ohm resis-
     tor.  A SPST switch could be used to ground pin 19.

     Another challenge would be finding a place on the R7000
     to  put  the  added  "Memory Bank" switch.  Perhaps one
     could use the Noise Blanker switch, and just leave  the
     NB on at all times.

     I don't have time to try this experiment, and would  be
     interested  in  hearing  results  from any enterprising
     hobbyist willing to try this.

     Long live tinkering!


     [PS:  Jack Albert, WA9FVP, reports that  he  tried  the
     modification,  and  it  works!   Jack  doesn't have the
     remote control option in his R7000, so  he  elected  to
     use the front panel REMOTE switch as a bank switch.  He
     installed a 48,000 ohm resistor between IC8 pin 19  and
     ground,  and ran a wire from the REMOTE switch, through
     an 82,000 ohm resistor, to pin  19.   When  you  switch
     between  banks, you must also rotate the channel selec-
     tor knob, forcing to the microprocessor  to  read  from
     memory.]