Microphone Modification; Modification For Out-Of-Band Transmission - Yaesu FT-100 Undocumented

feedback provided to the user while sending the tones. There are also 4 buttons labeled A,
B, C, and D but there is no documented use for these keys.

Microphone modification

This modification to the stock microphone will bring you excellent transmit audio
reports:
• Open the mic case.
• Remove the 3 larger internal screws and the 1 smaller screw in the microswitch.
• Move the PC board away from the tiny mic element so you can access it.
• VERY carefully remove the tiny electret mic element from its cylindrical housing
using a fine tipped tool. Work it out beginning at the edge where you can pull on
the rubber "grommet".
• Shake the plastic baffle out of the electret housing.
• Carefully force a sewing needle through the 3rd mic hole that's normally blocked.
• Insert the electret element back into its cylindrical housing carefully, leaving the
plastic baffle out.
• Re-assemble the mic case.
Set the MIC gain to about 55 and enjoy the excellent transmit audio that was previously
limited by the plastic "noise baffle". The improvement is dramatic.
Note that most hams in Europe seem to have an MH-42b microphone on their
FT100/FT100D (the version without DTMF buttons). The MH-42b mic DOES NOT
NEED THIS MOD. Instead of the two-out-of-three holes there is a slit in the mike
housing, and the plastic baffle is made out of loosely compressed fibers in this version,
which does not block sound noticeably. As a result, this mic doesn't have any audio
problems. So if you have an MH-42b mic, just leave it as it is. :-)

Modification for out-of-band transmission

The FT-100 can be modified to transmit on frequencies outside the amateur bands. This
modification opens the Yaesu FT-100 for full transmit on the HF, VHF, UHF bands. The
mod works for both the FT100 and FT100D. It will not allow you to transmit on the 220
Mhz band. All memory channels will be lost. Repeater offsets remain intact for USA
versions.
Back of front panel. Top left corner.
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