PRO2004
            6,400 CHANNELS FOR YOUR PRO-2004 SCANNER

                     by Bob Parnass, AJ9S

Chicagoan Denny Beringer sent in a few sheets he picked up at Dayton
describing a modification to expand the memory in the Radio Shack PRO-2004
scanner from 300 to 6,400 channels.

   The new circuitry adds 3 ICs, a 7 segment readout, a ribbon cable, a
pushbutton switch, and a few resistors and capacitors.

   First, diode D510 is added which expands the scanner from 300  to  400
channels. Then, IC504, the stock memory memory IC (a uPD446G), is removed and
replaced by a  ribbon cable leading to an added printed circuit board. The
additional board contains an HM62256 32Kx8 static RAM IC, which holds 16
groups of 400 channels each.  (note: if you don't do diode D510, I think
you'll get 4800 channels, though I haven't tried any of this. I heard that the
400 channel mod makes the markings on the 2004 keyboard incorrect.  WA2ISE)
CONTINUED IN FILE PRO2004.1