home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
World of Ham Radio 1997
/
WOHR97_AmSoft_(1997-02-01).iso
/
mods
/
icom
/
icom_r
/
r7000_08.doc
< prev
next >
Wrap
Text File
|
1997-02-01
|
2KB
|
42 lines
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.]