— W1HUE's Amateur Radio Site —
QRP Related Equipment Modification Articles

• INDEX Labs QRP-PLUS Modifications and Improvements

• Part 1: Receiver Modifications (January 1997 ARCI QRP Quarterly)
• Part 2: Transmitter Modifications (April 1997 ARCI QRP Quarterly)
• Part 3: Notes and Corrections (July 1997 ARCI QRP Quarterly)
• Fixing Transmitter "Chirp" (October 1997 ARCI QRP Quarterly)
• MTP3055E Temperature Stabilization (July 1999 ARCI QRP Quarterly)
• Latest info:   More Mods for the QRP-PLUS (Winter 2003 & Fall 2005 ARCI QRP Quarterly)

• QRP-PLUS & QRP Companion Manuals

• MFJ QRP-Cub Modifications (July and October 2000 QRP Quarterly)

• Improved Tuning Linearity by W1HUE
• Improved Sidetone Level, QSK, Keying Envelope by W1HUE
• Reducing Warm-Up Drift (good general tutorial) by W1HUE
• Simple RIT Mod by W1HUE
• Alternate QSK Mod by Cub Designer Rick Littlefield, K1BQT
• MFJ Cub Schematic and Parts Layout

• Miscellaneous Articles by W1HUE

• Peak Power Mod for the OHR WM-1/WM-2 QRP Wattmeter (January 1995 ARCI QRP Quarterly)
  • WM-1 Alignment & Schematic (578kB)
  • WM-2 Alignment & Schematic (187kB)
• Cleaner Keying for the Ten-Tec 509 (June 1995 NorCal QRPp)
• Improving SSB Performance of the Ten-Tec Argonaut 509 (October 1995 ARCI QRP Quarterly)
  • TenTec 1551 Speech Processor Manual (with updated schematic)
• Curing VHF Interference in Ten-Tec Argonauts (July 1996 ARCI QRP Quarterly)
• SAMLEX PSA-305 Power Supply Mods (October 1998 QRP Quarterly) Updated June, 2023
• • SAMLEX PSA-305 Schematics and Troubleshooting Guide
• NorCal 20 Modifications (April 2000 ARCI QRP Quarterly)
  • NorCal 20 Manual and Schematics (Scroll down to NorCal 20 . . .)
• Battery Booster for QRP – Construction article (not a mod) published in the April 1999 issue of QRP Quarterly. Some of the info on part numbers, etc. is out of date, but the general technical information is still applicable. I have found the little device to be very useful for in-the-field battery operation.

• Links to Related Sites

• More QRP-PLUS Mods & Tips
• AD6A NorCal 20 AGC Mod
• LA3ZA's Unofficial Guide to Elecraft K2 Mods (a "must" for K2 owners)
• HW-9 Mods by Gary Surrency, AB7MY
• Mods & Manuals for Rigs of All Types (must register to use this site)
• QRP-PLUS User's Group Email List
• QRP Amateur Radio Club International ^SM
• QRP Builder (useful building hints & gadgets)
• QRPGuys (low cost easy to assemble fun kits)
• QRP Labs (assorted kits and "stuff")
• 

  Free Filter Design Software (Link updated 7/14/16)