6000 Series radios - CAT connection with Acom 2000a amp solution

Bob Needleman

This is an issue that has been discussed before, but I thought it would be helpful to review it again since there has been some confusion on how to resolve it, based on what has been published on the users group.  I recently acquired a 6600M and wanted to connect it via a CAT cable to my Acom 2000a amplifier ( with the new style RCU). I reviewed the information in the Flex USB cable guide and obtained the 2 necessary cables - a USB to DB9 serial interface cable (with FTDI chip) and a DB15 to DB9 cable that goes between the Acom amp and the FTDI cable (I already had this, wired for Kenwood CAT control). After connecting the 2  cables and setting the CAT settings for the 6600M  listed in the Flex USB cable guide, along with the correct CAT settings in the amp (Kenwood (NEW), 19200 baud), I could not get the amp to correctly receive the band data from the radio. I contacted Jeff, KI0KB, who had a similar problem a few years back, and he quickly got back to me with the problem and the solution. The issue is that the USB/DB9 (FTDI) interface cable is switching the wiring of Pins 2 and 3 (TX TTL and RX TTL) of the Acom (DB15 to DB9) cable. To solve the problem, you can do 1 of the following:

1)  Rewire the DB9 connector on the Acom (DB15/DB9) cable - transfer the wire on Pin 2 to Pin 3 and vice versa,  (Do NOT attempt to re-wire the USB/DB9 cable since damage to the FTDI chip is possible) 

2) Insert a Null Modem cable in between the USB/ DB9(FTDI) cable and the Acom (DB15 to DB9) cable. This is wired to switch Pins 2 and 3.

I chose to rewire the DB9 connector on the Acom cable since I didn't have the correct null modem cable. The wires are quite small and close together so you need to be  careful to preserve the spacing between the 2 pins (I put a small piece of heat shrink tubing over one of the wires). After doing that and setting up the USB cable menu as per the USB guide (CAT, Baud 19,200, TX slice, etc), CAT control worked fine, with the amp following the 6600M perfectly on auto band and band segment changing. It might be helpful in future revisions of the Flex USB Cable Guide, where there's a section devoted to connection of the 6000 series to the Acom 2000a,for this solution to be published.

Thanks to Jeff, KI0KB for his assistance in helping me get this issue solved.

Bob K3AC

Jim Gilliam

Jeff Schwartz

Good job Bob! It would be nice to see that wiring diagram in print in the Flex USB cable guide as well as the ACOM 2000A manual. They are both are amazing pieces of equipment and work so well together. As an aside I and our club use my 6400M occasionally portable in Wyoming for WC7WB activity with an ACOM 600S amplifier. It has different wiring than the ACOM 2000A.... don’t get me started! I can’t tell you how much time I spent trying to figure out the CAT control wiring situation with both of those amps. It would be nice if these companies would keep their CAT control protocols and wiring the same at least in their own equipment line but I guess that what keeps it all fun and interesting... the challenge of ham radio. Good post Bob, glad I could help. 73 Jeff / KI0KB / WC7WB