This mini-project incorporates the trusty AIOC controller with a transceiver module (can be UHF or VHF) to make a self-contained USB-powered transceiver, suitable for use on AllStarLink nodes.
The Micro Transceiver has a low output internal antenna for in-room use, or an external antenna can be attached via the standard external SMA connector.
The rear panel also has the Hi-Lo power setting for the transceiver module and the single USB-C connector.
Looking inside the unit, the popular CM818 transceiver module sits alongside the the AIOC processor. Selectable UHF and VHF filters bring the transmission into compliance by virtually eliminating the harmonics (-40db).
The low power internal antenna is formed by a ‘leaky dummy load’ providing ample coverage around the shack, with the full power output available on the rear SMA connector when the board jumper is disabled.
Along with the TX lamp, a front panel COS indicator illuminates to show the squelch on the module is open; very useful for a quick check that you are using the correct CTCSS setting etc. The regular AIOC led activity indicators are also brought to the front panel to show data and CPU. activity.
The AIOC has a serial port that’s connected to the SA818 to provide channel programming and setting frequency, CTCSS, squelch level etc.
The above video shows the unit in operation using the echo facility in the ASL-Tune menu.
What’s next?
Currently I have a problem with the SA818 module working with the virtual COS due to vestigial noise triggering COS when it shouldn’t. To resolve this, the hardware COS from the SA818 is connected to a GPIO pin on the AIOC that will be used for an upcoming implementation of hardware COS support on the AIOC processor.
When the COS issue is fixed, I’m going to put this project into the public domain. The total parts cost is under $30 if you order the parts in quantity of 10, so ideal for a club project (you only have to solder on the SA818 and switch the filter to the desired band). I have 4 of this V1 model (with the spelling mistake on the front panel) that I’ll put on eBay – or email me if you are interested.