From - Sun Dec 01 22:35:28 1996
Path: 
nntp.ulg.ac.be!news.belnet.be!swsbe6.switch.ch!scsing.switch.ch!ubnsrv.unisource
.ch!newssrv.ita.tip.net!masternews.telia.net!newsfeed.internetmci.com!feed1.news
.erols.com!phase2.worldnet.att.net!uunet!in1.uu.net!200.220.64.7!news.unisys.com
.br!news.embratel.net.br!news
From: Ivan Blumenschein <ivsalati@omega.lncc.br>
Newsgroups: comp.sys.hp48
Subject: IR upgrade: no way!
Date: Fri, 29 Nov 1996 00:52:24 -0300
Organization: Inside Information Systems
Lines: 33
Message-ID: <329E5DF8.6171@omega.lncc.br>
NNTP-Posting-Host: rio-as3-tty08.iis.com.br
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
X-Mailer: Mozilla 3.0 (Win95; I)

I've read the article "irrange.txt" at 

http://mursac.marshall.edu/hp48/irrange.txt ,

opened my HP and soldered a 100k resistor in parallel with the 220k one.

(this should give me less than 80k in overall, and should be more than
enough to get the expected results). But when I closed it and tested,
the IR range has increased only some inches (from 6" before to about
10-15" after). I opened the calc again and soldered a thin piece of wire
in both resistor terminals (checked the connections etc). In the other
end of the wires I soldered a small female terminal. Closed the HP with
the ends of the wires outside, so I could try ANY resistor now. I tried
180k, 100k,80k, and no significant improvements. Went down to 33k
(giving an overall resistence of 28Kohm) and things stayed quite the
same. The resistor I'm messing around with has to be the right one, or I
wouldn't be getting any improvement at all.

Did anyone have success in this upgrade?

I used those cylindric (ceramic - I guess) resistors, not those flat

ones (like in the HP). I'm sure the used resistance values are right 

(I tested with a multimeter and I can read the color code) and all

results were obtained with the IR plastic cover off.

If someone can help, I'd be very thankful.

Ivan Blumenschein

ivsalati@omega.lncc.br