Designing a prototype tracker

We have been working for some time, designing a more complete prototype Arctic Tracker. The plan is to produce up to 10 units, with financial support from the Norwegian Radio Relay League. We will use a Tekal 12.30 aluminum enclosure (like the Polaric Tracker), it will have a display, and a PA module that can deliver 5 watts of RF output. A 2-layer PCB has been designed and will arrive later this week. The main differences between this prototype and the first lab-model are:

• PA module added. The radio-module is actually complete, but is just 1 watt. We considered using a transistor, but the simplest way to boost the output is to use a Mitsubishi RA07M1317M module (same as Polaric Tracker). It needs an attenuator on the input side since tranceiver module yields 0.5 watts and the PA module needs just 10-20 milliwatts. We also add a pi-filter to the output and a simple PIN diode switch.
• Use a 2200 mAh 7.4V LiPo battery since the PA needs this voltage. We then also add a switching regulator down to 3.3V.
• Add a pin-header for connecting a display (using SPI). The Nokia 5110 is cheap, easy to program and easy to mount in the box since it comes with a metal/glass frame.
• Remove one of the indicator LEDs to save space on the front panel. Remove pot. meter for TX audio (use fixed attenuator instead).
• Use SMD (mostly 1206) resistors, inductors, diodes and capacitors..

There are some adaptations to the PCB due to how it is going to be mounted in the box. Pin-headers, power-supply and some resistors will be mounted on the back-side of the PCB. The front-panel will be attached to the PCB using the SMA antenna contact and LEDs. The GPS modules, and pushbutton, socket for external charger (and maybe a on/off switch) will be attached to the front panel and connected to the PCB using wires.

The picture below shows the components that we intend to use in addition to the PCB board as well as the SMA socket. The GPS can be on the inside of the (plastic) front-panel. The space in the box will be tight, but hopefully it will work. We will also need to make a square hole in the box for the display. The space in the box will be tight, but hopefully it will work.

Schematic here.