A Simple Tuner Simulator for Icom HF Transceivers

by Igor Dobrokhotov, UN7GM

Fig. 1: Tuner Simulator Schematic.
Fig. 1: Tuner Simulator Schematic (Courtesy UN7GM, UN7RX)

Robert UN7RX has proposed one of the user-friendliest and simplest solutions for the IC-706 series; it will also work with other Icom transceivers fitted with the 4-pin Molex socket for connection of the AH-3 or AH-4 automatic tuner.

The UN7RX circuit consists of one-half of a CD4013, one resistor, two capacitors and one diode. When tuning, it is not necessary to switch modes or reduce RF power output; this circuit does all that automatically.

For the IC-756Pro3, configure the radio per p. 89 of the User Manual (Optional external tuner operation).

Simulator Operation:

  1. First push of TUNER button - LED blinking, no TX.

  2. Second push of TUNER button - carrier TX on, RF output 10W.

  3. Third push of TUNER button - TX off, normal RX.

Copyright © 2005, UN7GM and UN7RX
Text edited and page created by A. Farson VA7OJ/AB4OJ
Last updated: 10/12/2005

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