Direct connection from Flex 6600M to THP 1.5Kfx amplifier without DDUTIL

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  • Updated 9 months ago
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I am trying to control frequency band selection on a Tokyo Hi-Power HL 1.5Kfx linear amplifier  using an FTDI USB to serial port converter directly from the Flex 6600M rear panel USB port to the amplifier serial port using the Kenwood control protocol.
I would like to avoid using an external PC with DDUTIL.
The FTDI serial port is correctly recognized and the port settings are correct, but there is no communication.  Is the Kenwood protocol automatically selected when I enter CAT into the port setup menu or do I need to select the Kenwood protocol in some other menu.
I am running firmware revision on a Flex 6600M
Thanks for any suggestions.   W8GNM
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Geoff - W8GNM

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Posted 9 months ago

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Photo of K3SF


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see flex document on USB cable usage and setup

this should apply even using 6600M

i dont know if there are any setting in your amp that are required
i run a KPA500

Paul K3SF
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Dick B

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Note, I had to use a null modem cable, actually just wired two connectors back to back in null modem configuration. Wiring is on the Internet try Search.
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Art, N4PT

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Yes you need a NULL MODEM adapter. I used this This makes for a very neat installation. The adapter is at the 1.5 end of the cable.
The FTDI works very well except when you kill the slice TX flag the Tokyo-Hi power goes to 160 meters. 
Photo of WX7Y


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I am using these FTDI chipset USB Null modem cables and they have worked very well plugged into the FLEX 6700's USB ports and on the RS-232 side every thing else I have tried it on has also worked.

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Chris Tate - N6WM, Elmer

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check and make sure your USB port is working ok by turning on logging(blue button) and making sure there is telemetry..  then you can focus on the correct cable.
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Geoff - W8GNM

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Thank you all for the quick and helpful advice.   The problem was the need to place the RS-232 null modem, Tx/Rx crossover device, in series with the connection.  Everything is working well now.
A work around for the amplifier switching to 160m when the Tx slice is turned off is to trigger the COM port from TX ANT-1 instead of TX SLICE.   This keeps the amplifier on the right band regardless of whether the TX SLICE is enabled or to which tuning knob the TX SLICE is assigned.
73, W8GNM