Thetis Modifications to Support Acom 1200S/700S/600S Amps and 04AT/06AT Tuners

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Thetis Modifications to Support Acom 1200S/700S/600S Amps and 04AT/06AT Tuners

Postby K8EZB » Wed May 03, 2023 10:02 pm

A little more than a year ago I acquired an ANAN 7000DLE Mk II around which to build a new station. My initial focus was on learning the radio; once I had the radio working well, I moved on to build out the station by adding an Acom 1200S amp and companion 04AT tuner which I had owned for several years and used successfully with Icom and Yaesu radios. Adding the amp/tuner worked well with one exception. In an earlier post here on this topic I outlined in some detail a problem encountered with this combination of radio and amp . The 1200S + 04AT supports an automated TUNE function in which the amp sends a sequence of CAT commands which are intended to set the attached transceiver into RTTY/FSK mode to provide a carrier for tuner operation. A problem arises with the TUNE operation because the ANAN does not fully support the “standard” Kenwood CAT command set, and does not have a native FSK mode. Additionally, the amp sends an extended version of the Kenwood command set which includes certain commands (DT commands) intended to support sub-mode selection on some Elecraft radios. Standard Thetis does not recognize these commands and returns an answer of “?.” Attempting a TUNE operation under these conditions results in an amp protection fault and an abnormal end state for the ANAN. The amp TUNE function provides a one-button (one mouse click) hands-off automated tune feature which I consider a useful capability, so I set out to find a way to make this work with the ANAN.

My initial attempt at solving this problem was to engage with Acom-BG in Bulgaria in an effort to modify the 1200S firmware to support ANAN (and Flex) radios. Acom-BG acknowledged the problem but declined to commit to updating the amp firmware to achieve compatibility with the ANAN radio, and declined to provide the detailed documentation I would need to modify the amp firmware as they regarded this information as proprietary; Acom, however, did provide the details of the CAT command sequence sent by the 1200S during a TUNE. My next effort involved using third-party software marketed by Carl, N4PY, as Pegasus Plus. Carl was very helpful, and we were able to craft a solution which supported the Acom TUNE feature by using Pegasus Plus to act as a sort of CAT translator between the ANAN and Acom gear. This worked but with some side effects which were not entirely satisfactory. I lived with this solution until a couple of weeks ago when I decided to take on the task of modifying Thetis to support the Acom TUNE CAT command sequence.

The basic approach was to modify the Thetis CAT code to recognize and act on the Acom DT commands and to implement a workaround to provide a carrier for the tuner. A “workaround” because there is no native FSK mode in the ANAN radio. Instead, the modifications to Thetis use FM mode to provide a carrier; this is achieved by repurposing the DT commands sent by the amp to put ANAN into FM mode. This is necessary because the RTTY/FSK mode command (MD6) sent by the amp is interpreted by Thetis as RTTY (DIGL) mode which is for AFSK (no signal without modulation) instead of FSK. An additional requirement was that my changes to Thetis not result in changes in the way Thetis handles any other CAT commands (other than the DT commands which are not part of the Thetis CAT command set).

These modifications to the Thetis CAT software are fairly straightforward, involving the addition of perhaps 50 lines of C# code, with no changes in existing Thetis code. However, with no previous experience with Thetis source code, the C# programming language, and the Visual Studio software development tools, more time was required on my part than would have been required for someone experienced in these areas, and likely resulted in a less elegant solution. The Thetis CAT source code is fairly well organized, but sparsely documented with in-line comments (what I call “developer documentation” instead of “maintenance documentation"), making it more difficult to understand what the code is doing when reading through it. In any event, after editing, compiling, and testing this new version of Thetis ( with the Thetis CAT Testing feature, I installed it on my station computer and it works as intended.

I am happy to provide more details to those who may want to implement a similar solution. I also wish to acknowledge the encouragement and advice offered by Scott, WU2O, at several steps in this project.


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