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Battery charger and power inverter
By default, the FS-5000 radio station is powered by
rechargeable batteries.
The batteries should be charged after use by means of a special
battery charger that is part of the complete kit. Although it is possible to use
the charger stand-alone, it is normally used in combination with the mains
supply (PSU) that is stacked on top of it.
The batteries can be charged in situ.
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The image on the right shows the bare battery charger. The unit measures
approx. 145 x 185 x 35 mm and has a small control panel at the top-front.
One the control panel are buttons for starting a charge operation and for
checking the status of a battery. A series of LED indicators show the current
status. A 12V input allows an external (car) battery to be used as source.
On top of the unit are two contact pins. These are used to receive 14V power
from the mains power supply unit (PSU) that should be mounted on top of it.
This is the normal situation.
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On the left side of the charger is a large connector with 4 large contact
pins and 17 smaller ones. When the charger is used as part of a
complete FS-5000 radio station,
this plug is connected to the mating socket of
the transmitter.
In that case the charger is mounted in the rear right corner,
below the PSU. The control panel remains accessible
even when the DSU is installed.
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The batteries can be charged whilst they are installed
in the radio station as long as the charger is
connected to the transmitter. It is not possible however,
to operate the station while charging is in progress.
It is also possible to charge the batteries off-line.
In that case, the H-bar is used to connect
the batteries directly to the charger.
This mode of operation in shown in the image on the right.
In some countries (e.g. Germany) this method was mandatory,
and the PSU/Charger was never connected directly
to the transmitter.
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The main reason for not using the PSU/Charger directly with the radio
station, is the emission of spurious (radio) signals by the PSU. The PSU
is a Switched Mode Power Supply (SMPS) which can cause interference with
the reception of weak signals. This is generally called an EMC-problem.
The charger also contains a Power Inverter that allows any external
12V DC source, such as a car battery, to be used instead of the PSU.
The inverter transforms and regulates the external 12V source into a stable
14V DC voltage for the FS-5000. This may also cause EMC-problems.
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The charger can be opened from the top by removing the bottom panel,
that is held in place by 6 small bolts. It is roughly divided in two
sections that are separated by a metal wall that is part of the case.
Inside the unit are three PCBs of which the two at the left are stacked
together.
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The image on the right shows the
interior of the charger after the top
lid has been removed. At the right is the
power inverter that takes the 12V
from an external source and converts it into a stable voltage required
by the FS-5000. The circuit is built around an SG1524
Regulating Pulse Width Modulator by Microsemi Corp [1].
The board on the left is the
charge-management logic. It controls the
charge progress and checks weather the battery is fully loaded.
This board is connected to the smaller contacts of the
output connector
(at the bottom of the image).
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Below the logic board is another PCB with the
power source selection and supervision.
It selects between an external 12V DC source (regulated to 14V by the
power inverter) and the 14V input from the PSU.
The output voltage produced by the charger is supervised by an
SG1543
[2].
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© Copyright 2009-2013, Paul Reuvers & Marc Simons. Last changed: Saturday, 21 April 2012 - 09:23 CET
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