Modifications for the Icom AT-160

07-06-2001 Using the AT-160 with the IC-706MKII English language

Using the AT-160 with the IC-706MKII
Author: Dave Abshire Sr. - KG4KOX -

ICOM's IC-706MKII transceiver and AT-180 antenna tuner are designed to work together. However, ICOM's AT-160 is a very popular antenna tuner. Originally designed to work with the IC-728 and IC-729 transceivers (now out of production), the AT-160 will work with the IC-706MKII if the following instructions are followed:

  1. (IC-706MKII only, not IC-706) The IC-706MKII will transmit on VHF constantly when connected to the AT-160. To stop this, remove the wire attached to pin 6 of the DIN connector within the OPC-104 cable.

  2. Open the AT-160 and make sure the switch labelled "S1" on the circuit board is switched to the bottom, shown as "IC-725/726" in the AT-160 instructions.

  3. Make sure that the connections to the AT-160, using the OPC-319, OPC-104, or OPC-125C cables, are according to the AT-160 instruction manual. ICOM America suggests using the OPC-599 adapter cable for connection of the OPC-104 to the IC-706MKII.

  4. Connect the radio to the transmitter terminal and connect an antenna to the ANT terminal. Make sure the antenna has less than a 3:1 SWR. Place the radio in FM, AM or RTTY mode and key the mic. The AT-160 will now tune properly.

  5. The tuning button on the front of the IC-706MKII will not operate when using the AT-160 antenna tuner. This feature was designed to work with the AT-180.

  6. Check the SWR presented to the radio. It should be less than 1.5:1. The AT-160 operates with the IC-706MKII as it would with the IC-725 or 726 transceivers. Included with the AT-160 instructions is a page dedicated to the antenna tuner's operation with an IC-725 and IC-726 transceiver. This is not the way the AT-160 operates with the IC-706MKII.

  7. There is no way to turn the AT-160 off or place it into "thru" mode when operating with the IC-706MKII.

Extra note from Dave KG4KOX:

I cut one end off the OPC-104 that came with the AT-160 and used the small 13 pin adaptor that came with the 706 MKII. NOW you must leave pin 6 un-connected or your radio will stay keyed on 2 meters.

I did the mod and it works great on HF but I can't get it to tune proper on 6 meters, It will tune to a 1:1 then next time you key up it will retune again. If anyone knows a way around this please let me know.


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