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6
FIELD ALIGNMENT PROCEDURE
The procedures below do not constitute an exhaustive test or a complete alignment of
the module, but if successfully carried out are adequate in most circumstances.
TCXO calibration may be periodically required owing to normal quartz crystal
aging. A drift of 1ppm/year is to be expected.
Each alignment phase assumes that the preceding phase has been successfully carried
out, or at least that the module is already in properly aligned state with respect to
preceding conditions.
6.1
Standard Test Condition
The following equipment and conditions are assumed unless stated otherwise:
• AF signal generator with 600 Ω impedance, 150--3000Hz frequency range, with
level set to 387mV RMS.
• Power supply set to 13.8Vdc, with a current capability of >5A.
• RF 50 Ω load, 30W rated, return loss <-20dB.
• Jumpers set to factory default positions.
6.2
VCO Alignment
1. Select a channel at the centre frequency (half way between the highest and lowest
frequencies for the model in question).
2. Disconnect the Audio input (no signal input).
3. Key the PTT line.
4. Measure the voltage between pins 9 and 1 of the test socket (TUNEV), and adjust
C99 to obtain 4.5 ± 0.2V, while the TX LED is ON and the ALARM LED is OFF.
6.3
TCXO Calibration
1. Select a channel at the centre frequency (half way between the highest and lowest
frequencies for the model in question).
2. Disconnect the Audio input (no signal input).
3. Key the PTT line.
Page 14
RF Technology T220
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