CTCSS encoders

Note: If you need full CTCSS functionality the www.piexx.com FTS7-apx is probably the way to go. This page is about encoders only.

The simplest solution is analogue -- use an NE567 to generate the required frequency. Pro: cheap. Con: frequency drift, single frequency. Here's VK2KUR's version via VK2BV, or look at N1HFX's version which uses an active filter.

Digital solutions:

• Tony Hunt, VK5AH designed a CTCSS encoder using a PIC16C84, with six switches so that you can select one of 32 frequencies.
• John Kent, VK3BIZ redesigned this using an 8 pin PIC12C508 which can do one of four tones.
• Terry ZS1AYJ cut it down to one tone only, using three bits and resitors for D/A, and a PIC12F675.
• The Magalies Radio Amateur Club ZS6MRK did something similar using a PIC12F629 and surface-mount components -- I have one of these in my TR-9000
• Reg ZS1ADC makes PCBs and programs PICs for a re-layout of ZS1AYJ's design. I obtained some PCBs and programmed PICs from him.

ZS1ADC Design

Same schematic as ZS1AYJ.

Different PCB.