To boost TX audio, turn on the “MIC-EQ” from the display screen function buttons.
Set “SSB out level”, menu number 107 to 80
Set “SSB TX BPF”, menu number 110 to 300-2700
Set the following menu numbers to the values shown.
(For original FT-991 without updated firmware, menu numbers will be 2 places higher)
Yaesu Serial Number Info:
Year, Month, Production Number, Unit number
4 = Year (2004) N = Month (Months start with C for January so N = December) 96 = Production Number and 0040 = Unit number.
C = January, D = February, E = March, F = April, G = May, H = June, I = July, J = August, K = September, L = October, M = November, N = December
Service Menu : WARNING – Do not change the service menu settings unless you are qualified to do so and with all appropriate test equipment.
Power up while holding in FAST, A/B, and A=B buttons
To save changes, press and hold MENU/SETEP button until radio restarts