Fitting An Ultracap (A.k.a. Supercap) - QRP Labs QLG2-SE Manual

the LEDs visible on the front panel of your equipment. After all, which of us does not like
blinking lights on his equipment, and generally the more the merrier.
In this case, you can connect wires at pin header PH1, as follows in the diagram (right).
The cathodes (negative, indicated by black lines)
of the LEDs are connected to the pads nearer
the center of the board; the anodes (positive,
indicated by red lines) are connected to the pads
nearest the board edge. The sequence of the
pads, is as three pairs from left to right, as
Power (RED), Serial data (YELLOW) and 1pps
(GREEN) – in other words, the same order as
that of the SMD LEDs on the board.
You would also need to cut the thin exposed
tinned copper traces on the underside of the
PCB, in order to disconnect the onboard LEDs. This should be done with a sharp knife,
carefully so as not to damage any other nearby traces.
3.4

Fitting an ultracap (a.k.a. supercap)

There is a place on the QLG2-SE board to fit an ultracap (a.k.a. supercap). This is a lot
more reliable means of providing backup power, than the little rechargeable battery on the
QLG1.
Backup power permits the operation of the internal Real Time Clock (RTC) in the GNSS
module and also retains the downloaded satellite ephemeris data, which will enable a hot-
start (satellite fix computation) within a second or two of power-up.
Most amateur radio applications will not need this, but the pads are made available on the
board in case you do wish to use it.
Be careful to observe the correct polarity to avoid a possible bang and a nasty chemical
mess (don't ask me how I know about this, either). The black arrows on the capacitor
body point to the negative pin.
The photograph shows a 0.47 Farad, 5V capacitor installed on the QLG2 board. The
position is the same on the QLG2-SE board.
The pads are separated
by 0.2-inches (5.08mm)
and the capacitor fits
perfectly. This capacitor
appears sufficient to
backup the QLG2 GPS
for at least 12 hours.
7
QLG2-SE manual 1.00