Fixing "Tinny" Transmit Modulation By Adjustment; Fixing "Tinny" Transmit Modulation By Microphone Modification - Philips FM92E Manual

28: Fixing "tinny" transmit modulation by adjustment:

Some FM-900's sound fine on air, some have a quite "tinny" sound. The simplest way to cure this is by slight
adjustment of the "modulation Balance" potentiometer (R371) on the Synthesiser Board. It is the innermost of
three potentiometers, and looking from the "track" side of the board, adjust slightly anticlockwise (only a few
degrees) to increase both bass response and overall deviation.
Warning!. Do not make large adjustments here, as you could cause over-deviation!

29: Fixing "tinny" transmit modulation by microphone modification:

Some FM-900's sound fine on air, some have a quite "tinny" sound. Another way to fix this is to replace the
standard microphone insert with an electret insert, available from various electronics suppliers.
30: Fixing "tinny" transmit modulation by microphone modification:
Simply "flip over" the microphone insert. Truly! This places a "baffle" (the back of the insert) between you and the
microphone element, which helps to reduce response peaks.
Philips FM92E Conversion to 6 Meters: Version 3.9 Page 63