8
Mechanical mounting considerations
The kit is supplied with four 12mm nylon M3 hex spacers, and
four nylon M3 screws. The PCB has a suitable mounting hole
in each corner.
The patch antenna specifications recommend that the
distance between the ground-plane and any conducting
materials below it, should be a minimum of 10mm.
When using the supplied patch antenna, the recommended
mounting of the QLG1 PCB should therefore involve the PCB
orientated with the component side downwards, and the patch
antenna facing up to the sky. The hex nylon spacers should
be used as pillars, suspending the PCB above the enclosure.
The hex nylon spacers will be on the component side of the
PCB (lower), with the screws on the solder side (upper).
The enclosure material must NOT be conductive, which would
shield the patch antenna!
If using an externally mounted active antenna, the mounting considerations are
much less critical.
Input/output signal connections
The diagram (right) shows a section of the silkscreen printing from the component
side of the QLG1 PCB, at the right side of the board.
There are two sets of connections, a 6-way set and a 4-way set. Both use 0.1-inch
pitch pads, suitable for using standard 0.1-inch pin header connectors (not supplied
with the kit), or soldering wires. The pads are large and easy to solder to.
The 6-way set of connections provides access to the full set of signals, for general
purpose use of this GPS receiver module. Note that TXD is the serial data output of
the module, at 5V Logic levels. The 1 pulse per second (1pps) timing signal is also
5V. The pulse is 100ms long and active-high (the leading edge of the pulse indicates
the 1 second event). RXD is the serial data input signal, at 3.3V logic level; however
5V logic level inputs are also supported due to the onboard zener diode D1.
The 4-way set of connections is intended for connection of the QLG1 GPS receiver module to the
Ultimate3S QRSS/WSPR transmitter kit, and other QRP Labs kits. These are the only four signals required
by these kits, which do not communicate serial data back to the GPS, they only listen to the GPS serial
data stream and 1pps signals.
Connecting the QLG1 to an Ultimate3S QRSS/WSPR kit
The 4-way connector on the QLG1 can be connected directly to the 4-way connector of the U3S (and other
QRP Labs kits), via a length of shielded cable. No pull-up resistors, extra voltage regulator, or
smoothing/decoupling capacitors are needed since these are all already incorporated into the QLG1. The
order of connection pads on the QLG1 is also the same as those on the U3S. Note that the QLG1 TXD
(output) signal connects to the U3S RXD signal (input). The cable shield should be connected to ground at
the U3S end only, not the QLG1 end. 2m or 3m of cable is typically a good length to use.
