BX-245 • 7
© Box 73 Amateurfunkservice GmbH 2019
piezo buzzer and locate the positive termi-
nal. Fit this component so the positive pin
points in the direction of the battery holder.
Next fit the battery holders, observing cor-
rect polarity (Fig. 2). Caution: the spring
contact is the negative pole. The solder ter-
minals of the battery holders are made of
spring steel. Use suitably robust side-cut-
ter-pliers to trim the excess length of the
switches, battery holder and buzzer termi-
nals, making sure that these terminals do
not touch the housing later.
Finally, fit the BNC socket and solder on
the board. Again, this part must sit flush and
be aligned horizontally and at right angles
to the edge of the board. The two ground
pins are to be soldered on the underside of
the board with a 100 W soldering iron to
ensure the solder flows well in order to
avoid cold solder joints. At the same time,
the soldering time should be kept relatively
short so that the insulation inside the socket
is not damaged (Fig. 10). The thin terminals
should also be cut after soldering in order
to avoid short circuits with the housing.
Functional test and final Assembly
Before installing the board into the hous-
ing, a short functional test is required. First
fit the three plastic caps on the push-but-
tons and fit the previously assembled dis-
play in the corresponding sockets. Ensure
the slide switch is set to the off position
(Fig. 10), then insert two 1.5 V batteries
with the correct polarity and switch on the
device with the slide switch.
The start-up welcome message should
now appear briefly on the display, the FA-
VA5 then switches to measuring mode.
If the display remains blank, then all sol-
der joints made in the previous steps must
be carefully checked and reworked if nec-
essary. Once the functional test is complet-
ed, move the slide switch back to the off
position and remove the batteries from
battery holders. The fully assembled board
is shown in Fig. 9.
Installation in the enclosure
First, the four rubber feet are inserted into
the lower shell of the enclosure. It is helpful
to pull with the flat-nose pliers on the thin
rubber nipple on the inside and at the same
time to turn the rubber foot slightly. Then
cut the protruding rubber nipples to 2 mm
with the side cutter (Fig. 11) so that they
do not touch the board later. The board is
Fig. 9: FA-VA5 Main Printed Circuit Board: fully assembled (6-pin header is obsolet)
Fig. 10: Slide switch in position
Off
