Here are a few useful mods for the FRG-100:

1. Noise Blanker: This increases the effectiveness of the NB by
altering the noise blanker AGC characteristics. I find it lowers the
NB trip threshold and improves the attenuation of line noise type of
interference. To accomplish it just solder a 47K resistor across
capacitor C1005 (10uf, 50V.)

2. If you use ECSS mode as I do for fading SW broadcast stations,
this mod will equalize the volume when switching from AM mode to SSB
mode on AM stations. As designed the AM mode is louder and you have
to increase the volume when going to SSB (ECSS) mode. This mod
reduces the AM volume to match the SSB level. Solder a 2.7K or 3.0K
resistor from the + pin of C1205 to a ground point. This reduces the
AM detector output level.

3. Audio: If you want a more pleasant AM audio with more highs snip
out completely capacitor C1164 (small 220pf ceramic). This cap rolls
off the highs in amp Q1026-2.

Frank
K3YAZ
Tucson