Yaesu FTS-8 CTCSS Replacement (Encoder Only)

Jakub SQ9PDJ

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About

This project is the result of creating an FTS-8 CTCSS module for a Yaesu FT-736, owned by my friend.

It's a recreation of the PCB from an existing 2003 project by Juha Niinikoski OH2NLT:
https://www.jumaradio.com/oh2nlt/Ctcss/ctcss.htm

I created this PCB to make an order with a PCB manufacturing company.
The schematic is electrically identical, with only a slight reordering of part numbering.

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PCB design and documentation are licensed under the MIT License. The PIC16F628A firmware originates from the OH2NLT project and is included with the permission of the original author.

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Release Rev. 1.01 — December 2025

This project is released as Rev. 1.01, but the PCB pictures are from Rev. 1.00.

Initially, this project was created for personal use only, so I did not pay much attention to using regular (unpolarized) capacitor footprints for tantalum capacitors.
I only needed to pay attention to polarity when soldering.

In Rev. 1.01, the footprints of C12 and C13 were changed to polarized tantalum capacitors.

This project also includes KiCad files, if needed.

Release Rev. 1.02 — July 2026

In Rev. 1.02, the footprints of C12 and C13 were changed and now both are 1206 hand solder.

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Features

• Yaesu FTS-8 CTCSS replacement module, working only as an encoder – intended for use with repeaters.
• Can be used with 9V or 5V PTT signal transceivers – see the build section for details.

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Programming the PIC Microcontroller

The PIC16F628A is programmed using FTS-8_CTCSS_hex.zip
This hex file originates from the OH2NLT project

The IC can be programmed using an 8-PIN SOIC Clip with correct placement.
I used an XGecu T56 Pro programmer.
Programming can be done before or after soldering the IC to the PCB. Use any suitable programmer that supports PIC16F628A.

HOWTO attach the SOIC clip

Important: You need to omit 3 rows of pins from the top of the IC and the last 2 rows from the bottom.
Omit them in the same way on both the programmer and the IC.
Pay attention to the orientation of pin 1 on the IC.

          PIC16F628A
       ----------------
   x - |#1          18| - x
   x - |2           17| - x
   x - |3           16| - x
|----------------------------|
|# VPP |4           15|      |
|  VSS |5           14| VDD  |   8-PIN
|      |6           13| DATA |  SOIC clip
|      |7           12| CLK  |
|----------------------------|
   x - |8           11| - x
   x - |9           10| - x
       ----------------

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Building the PCB

Bill of Materials

Reference	Quantity	Value	Description / Footprint
C1–C9	9	100 nF	Capacitor_SMD:C_0805_2012Metric
C10, C11	2	33 pF	Capacitor_SMD:C_0805_2012Metric
C12	1	1 µF	Capacitor_Tantalum_SMD:CP_EIA-3216-18_Kemet-A_HandSolder
C13	1	2.2 µF	Capacitor_Tantalum_SMD:CP_EIA-3216-18_Kemet-A_HandSolder
C14	1	1 nF	Capacitor_SMD:C_0805_2012Metric
D1	1	LED	Diode_SMD:D_0805_2012Metric
J1	1	Conn_01x08	PinHeader_1x08_P2.54mm_Vertical
J2	1	Conn_01x06	PinHeader_1x06_P2.54mm_Vertical
R1, R2, R3, R4, R5, R8, R11	7	10 kΩ	Resistor_SMD:R_0805_2012Metric
R6	1	22 kΩ	Resistor_SMD:R_0805_2012Metric
R7	1	1 kΩ	Resistor_SMD:R_0805_2012Metric
R9	1	6.8 kΩ	Resistor_SMD:R_0805_2012Metric
R10	1	47 kΩ	Resistor_SMD:R_0805_2012Metric
U1	1	PIC16F628A-ISO	SOIC-18W 7.5×11.6 mm, P1.27 mm
X1	1	4 MHz	Crystal_SMD_HC49-SD

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Schematic

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PCB Rev. 1.00 Soldered Set

Show images

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PCB Rev. 1.01 3D View

Show 3D images

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PCB Rev. 1.01 Elements Placement

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Gerber Files

SQ9PDJ_FTS-8_CTCSS_(OH2NLT)_Gerber.zip

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Soldering Components on the PCB

When soldering, pay special attention to the placement of:

• D1 0805 LED
• C12 and C13 1206 tantalum capacitors
• PIC16F628A

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About R6 Resistor

• For the Yaesu FT-736 (and other 5V PTT Yaesu transceivers), leave R6 unpopulated.
• It is part of the voltage divider required for the Yaesu FT-4700 (and other 9V PTT Yaesu transceivers).
• Check your radio before populating this resistor.

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2025
By Jakub SQ9PDJ
73!