I now participate in the monthly Adventure Radio Society Spartan Sprints (https://ars-qrp.com). For that event, your score is based on (Number of Contacts) / (Weight of Station in Pounds). The 'Station' is defined as everything that you are using, up to your antenna connection. So, having a very light Station is desirable.
I was able to purchase a used ATS III-B.1 model from NM5S. It was installed in an Altiods tin and was ready to be taken out on portable operations. All accessories were mounted in a nice plastic case. However, my goal was to make my Station as light as possible for use during the Spartan Sprint. The AST III-B and Low Pass Filter (LPF) mounted in the Altiods tin weighed 2.64 ounces with the power cable. The empty Altiods tin weighed 1.27 ounces. I produced a 3D printed case that only weighed 0.23 ounces and then moved the ATS III-B board into that lighter case. I also produced a 3D printed Micro Straight Key for use with this radio.
The photos shows my complete ATS III-B based Station, along with the weights of the individual components.
Whole Station - Click on the image for a larger view
Transceiver - Click on the image for a larger view
Transceiver - Click on the image for a larger view
A LPF Board - Click on the image for a larger view
Micro Straight Key - Click on the image for a larger view
Earbuds - Click on the image for a larger view
350 mAh 2s LiPo Battery - Click on the image for a larger view
The ATS III-B uses band specific Plug-in LPFs, so my total station weight is based on how many bands I use during the event.
1 Band - 2.92 oz ( 0.1825 pounds) when using the 350 mAh 2s LiPo Battery.
2 Bands - 3.12 oz ( 0.1950 pounds) when using the 350 mAh 2s LiPo Battery.
3 Bands - 3.32 oz ( 0.2075 pounds) when using the 350 mAh 2s LiPo Battery.
Band Specific LPF Boards - Click on the image for a larger view
This may be about as light as I can get with this ATS III-B.1 model. The bare ATS III-B.1 board weights 0.87 ounces. Earlier ATS models may have had boards that were a little lighter. But I'm happy with the user interface on this more advanced ATS III-B.1 model. Some 'accessory' items could be considered I guess. The phono connector for the antenna is kind of 'heavy'. The 'light weight cable' on my home-brewed Straight key adds 0.17 ounces, which is more than the micro key itself weighs. The power cable and connector is a 'luxury'. But, trying to reduce those accessory weights by direct connecting stuff would make using the radio inconvenient, and in my mind is not worth it. However, I may experiment with using a smaller battery - I might not need 350 mAh of capacity to go the whole 2 hours.
It has been interesting to take a step back from my QCX and QCX Mini SDRs and try out this older ATS III-B.1 transceiver.