Yaesu FT-857 Manual

Installing a LIF port into the FT-857/897 transceiver

Introduction
This document describes the procedure for installing a LIF (Low Intermediate
Frequency [9 – 18kHz]) port into the FT-857/897 transceiver. This procedure
requires a level of expertise sufficient to dismantle the transceiver and to solder.
Nonetheless, the installation is straight forward and should not cause any
difficulties for the experienced radio amateur.
It is important to unplug all connectors and power before working on any
transceiver. It is also important to be grounded to avoid static discharges.
Please note: no responsibility or liability will be taken by the author of this
document for any damage or malfunction caused by user modifications.

LIF port installation

Dismantling the Transceiver

The top cover of the radio must be removed. There are 7 screws that need
to be removed and then the lid will become loose; there are 3 screws on
the top cover and 2 on each side. Remove the lid carefully; the speaker
cable will still be connected to the circuit board. Unplug the speaker.

Connecting the RG174 cable to the PCB

Solder the ground shield of the RG174 to the first 3 pins of J23. This will
also make the option filter 1 selectable in the radio's menu. Pin 4 is the RF
and it needs to be connected to the center of the RG174 coaxial cable and
to the input of the 455kHz filter. The center pin of the filter is connected to
pin 2 of J24 and the output is connected to pin 3. The filter is secured on
the PCB with double sticky tape. The filter will keep the AGC function