Yaesu FT-101EX MODS

I purchased my FT-101EX on October 21, 2012 at the Kalamazoo Hamfest. The yellow sticky on the rig said "lamps come on but no RX/TX". It took 4 hours of intense cleaning to get it up and running.

This rig is a joy to operate and work on. Initially, I performed mods to countermeasure potential failures that would be caused by the aging component parts. Once I had it up and running with fresh capacitors in the power regulator board and new bypass and coupling capacitors I started to modify the rig for ESSB and improved AM operation.

WARNING: I enjoy wide band SSB (ESSB) and AM operation. The modifications below are designed to achieve my goals. TX bandwidth is controlled by equalization but RX is stuck at 6KHz. These mods are not for everyone.. please consider this before performing them on your rig ;-)


The modifications detailed below are not my own design. I had lots of help from many hams along the way.

N3ZI Digital VFO 1000

The FT-101EX worked great for AM but SSB... drift drift drift.. so I purchased a Digital VFO from Electronic Specialty Products.. works GREAT


This modification bypasses the restrictive components in circuits between mic jack and the Balanced Modulator. I applied the audio from my rack to pin 8 of PB-1315 (AF Unit). In order to achieve this, I unsoldered the leg of C47 that connects to pin 8 and applied the audio from my rack to this point. (I installed a small SPDT switch that I use to select the audio source):



This modification is very easy.. simply install a 6KHz filter in the SSB filter slot on PB -1183. You may use the Yaesu filter (XF-30B) or an aftermarket filter from INRAD.

SPECIAL NOTE: If you install the 6KHz filter in the SSB slot, you will not need to perform the mode switch modification to enable the filter in AM mode. (the stock AM circuit uses the narrow SSB filter for AM RX). If you use this option (installing the 6KHz filter in the SSB filter slot), you will have very wide SSB TX and RX.. and you will not be able to null all of the carrier out of the SSB transmission unless you perform the crystal modification described below.

Crystal Modification (6KHz bandpass)

Under Construction.. I am still tweaking this mod. I purchased two crystals from International Crystal and installed them. My goal is to shift the carrier point so adjustments can be made to null out the carrier on each side band. Stay tuned for more information about this mod. Below is a visual of the stock crystal configuration and my work in progress idea.


PB-1315 Audio Unit Mods

Change C45 from 0.1uF to 10uF (25v electrolytic with + towards base of Q9)

Remove C39 (0.047uF)

Change C43 from 0.01uF to 10 uF (25v electrolytic with + towards of Q9)

Change C44 from 220uF to 750-1000uF at 10V

Change C40 from 33uF to 150uF