Manufacturing Issues; Marking And Labeling Issues; Alignment Range And Switching Range - Adcon A440 Technical Reference Manual

The A431 Radio Module
An Automatic Level Control (ALC) system is responsible for keeping the output pow-
er constant, regardless of the external influences (temperature, VCO excitation and/
or supply). A small part of the RF energy is rectified by D2 and applied to the U5:A
amplifier. By means of U5:B, the power is controlled according to the pre-set power
level (ALC input). U5:A is basically an analog comparator between the actual and the
programmed power output. Depending on the error signal obtained, a variable volt-
age is applied on the PD input of the PA chip, thus effectively controlling its output
power. In addition, the actual power output level is fed to the U6 analog switch and
presented to the RSSI/PO output while the unit is switched in transmit mode.
The modulation is applied on two-points: the VCO and the reference oscillator—this
is needed to obtain a flat response in the audio range from 10Hz to 2.5 kHz and com-
pensate for the counter-effect opposed by the synthesizer loop. The input signal
(must be 1 Vpp) is fed through a resistive divider (R14/R13) to the "cold" end of the
varactor diode controlling the VCO (D1). At the same time, the same modulation
signal is applied to the inverting op-amp U4 and then to the OSC1 reference oscil-
lator (a VCTCXO). The modulation signal is inverted in order to bring it in phase with
the VCO modulation point.
3.3.

Manufacturing Issues

3.3.1.

Marking and labeling issues

The A431 Module is manufactured in two versions:
From a manufacturing perspective, the difference between the high and low band
are the two helical filters FL1 and FL2 used on the receiving chain. The low band ver-
sion is marked as A440-44 while the high band is marked as A440-46 (when the
modules are included into the A440 Wireless Modem).
3.3.2.

Alignment Range and Switching Range

The A431 radio module's alignment range is 20 MHz, while the switching range is
10 MHz. According to the definitions formulated in the ETS 300220 and ETS 300013
specifications, the A431 radio module (combined with the A440 Wireless Modem)
belongs to the AR1 category. Therefore, for the European testing, two units should
be presented for test purposes, as follows:
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• Low band—able to operate between 430 and 450 MHz
• High band—able to operate between 450 and 470 MHz
• One A440 unit containing an A431-44 radio module, alignment range 430-
450 MHz, switching range 433-443 MHz
• One A440 unit containing an A431-46 radio module, alignment range 450-
470 MHz, switching range 455-465 MHz.