Ham Radio Modification files make up the most common collection of files that show up in textfile collections, because they're the bits of information that sounded devious enough to sound like they belonged in the file sections of a lot of BBSes people frequented.
The files were necessary because the Government decided that there were certain ranges of frequencies that should not be listened to by anyone. These included Cell Phone frequencies and the like. Instead of asking Cell Phone manufacturers to improve the technology behind their transmissions to protect the users of Cell Phones, they too a Typical Solution. They said that no manufacturer of radio scanners could listen to those bands anymore.
Naturally, this approach stunk on many levels, but one of the results of this law was that scanner manufacturers would simply throw in an extra chip or wire that would disallow the scanner to be used in the excluded frequencies. Suddenly, turning your scanner back into a full-featured piece of equipment merely became a matter of removing that chip or clipping that wire. So, files explaining how to do this for all the brands of scanners became legion. Here are a good amount of them.
6400 Memory Channel Modification to the 2006
Bearcat 200XLT Cellular Frequency Restoration
How to Modify Your ICOM R7100 To Provide an output Directly From the Discriminator, by Tim Jackson
Messages about Scanning in the 800mhz Range
Modifying the Chip on a Early Uniden 858 Chassis
Panasonic 900MHZ Cordless Freqencies
A Uniden/Bearcat 100XLT Scanner Preview by Bob Parnass AJ9S
Converting a Bearcat 140 to a 16 Channel Machine
Cellular Restoration of the Uniden/Bearcat 200/205XLT Test Mode by Bob Parnass, AJ9S
Bearcat 200 Cellular Frequency Restoral
Weather Satellite Reception on a Bearcat 210 Scanner, by Steve Warley
Modifying the Bearcat 760XLT for Cellular Frequencies
Modification of a Bearcat 760XLT for Cellular Phone Bands
Restoring 800mhz on a Bearcat 890XLT
Cellular Restoration of the Bearcat 950XLT
Restore the Cellular Freqs. on Your BC200/205XLT!
So You Just Gotta Know Everything About Cell Phones
Determining what Frequencies are used in the Cellular System and what Cells use which frequencies
Cordless Modifications, by Bob Kay, Monitoring Times
Making a Cordless Telephone Antenna, by Adam Gott
Modifying the Alinco DJ500t for Cellular Frequencies
Modifying a DJ500 to Broadcast Outside of the Ham Radio bands
Yaesu FL2100B 12 Meter Modification by Bill Walton
Expanding the Uniden HR-2600 for more Frequency Coverage
Fixing Up a Few Problems with the HT-2600
Getting the Uniden HR-2600 to listen to UHF/VHF
Thoughts of Cordless Phones, by Bob Kay, from the Scanning Report
HF, VHF, and UHF Modifications for Almost Everything
Modifying the Radio Shack Pro-34 Scanner
Modification of the AEA DX Handy Radios for Operation from External 12 volt Power
Modification of the AEA DX Handy Radios for Operation from External 12 volt Power (Part II)
Azden PCS-4000 Busy /Scan Mode Modification
Azden PCS-4000 Busy /Scan Mode Modification
Azden PCS-4000 Busy /Scan Mode Modification
Modifying a PCS6000 for 138-160mhz
PRO-37 Scanner Modifications (September 24, 1991)
List of modifications for the Kenwood R-5000 Reciever
Kenwood R5000 Modification Notes by E. Roskos
Information about the FCC's Scanner Law Notice of Inquiry by Benn Kobb
Message about the new Scanner Law
Other Message About the New Scanner Law
Third Message about the Scanner Law and a Call to Petition
Scanner Modification for Fun and Profit, by Hotrod
Enabling Out of Band Transmissions of the Kenwood 231a Radio
Modifying a TS430 For Cellular Frequencies, in 2 easy steps
Modifying the Kenwood TS-930 Trancievers for Cellular Frequencies