Subject: Boost IR range! Easy hack! 12 feet+ range! 
From:gsmarlow@ouray.cudenver.edu (Scott Marlowe)

FOUND IT!  I found that freakin resistor that cripples your HP 48G/GX's
IR port receive function!  If you have it open (see other files on that,
I'm not talking ANYONE through that one alone,)  lay it face down on a
work table.  With the bottom closest to you, you will see a small SMD
resistor labelled 224 right next to a 74HC00 IC (on the GX) or next to a
blank 14 pin spot on the G.  This is a 220k resistor.  With it in place,
and my IR port cover off, I measured a receive range with my JVC remote
of about 6" max for reliable programming under the REM34 program.

When I replaced this resistor with a 47k one (number will be 473, i.e.
47x10^3) My range is now at LEAST 12 feet.  I was able to read the remote
from across my freaking kitchen!!!  How very cool.

Tested the above with a JVC remote from 30 feet, and it worked GREAT.
Makes the REM program quite useful now, since you basically can bounce
signal off the wall and get a good read.
Popped the calc back open, and went from a 47k to a 100k resistor, and
still got 30+ feet.  SOrry I couldn't test any longer distances, but my
living room   and hallway are only so long...

I had tried a 200k resistor (isntead of the 220k built in) but got
the same dismal 6" max range with that.  One thing I am worried about is
power consumption, but unless this is a non-linear increase in current,
I should be looking at no more than an increase of two times power
draw with half the resistance (100k vs 220k) so I'm willing to
be a guinea pig for a week or two.