U3 QRSS TX

I had a spare unused QRP Labs U3 (not an S version that needed a home). In the end I decided upon using one of the custom cases from QRP Labs. This a standard enclosure that is supplied for other kits, such as the U3S, Clock Kit etc, but you can specify the end plates to suit a project. This means that you get a nice generic enclosure that can come with a properly cut out LCD hole to make projects look nice.

I built a simple tri-voltage PSU. Outputs are 5v (for the CPU) and 9v and 12v for use with the PA stage (only one used at a time). The 12V DC input feeds a 7805 / 7809 / 7812 set of fixed regulators, via an idiot diode on the input, and a 100uF electrolytic capacitor from smoothing. Each regulator also includes 0.33u at the input and 0.1uf at the output end as recommended by the spec sheet. Rubber feet were attached to the stripboard PSU and then these feet were glued to the enclosure. That meant that no holes needed drilling, this removing the possibility of drilling mishaps, and left the enclosure able to be re-used in the future if required without damage.

The front panel included a Phono and BNC input, in order to accept the 1pps and data outputs from the matching QLG2 GPS unit (I needed to drill the front panel holes a big bigger for this, and then added an SO239 and DC input for the rear panel.