technical manual for sailor compact hf ssb t2130 - Gopher Proxy

2 INSTALLATION MECHANICAL HF SSB TRANSMITTER T2130
SUPPLY VOLTAGE WATCHING
The battery voltage is measured 4 times per second. The battery voltage is measured as described in
section 2.3.3.5. CALIBRATION OF THE T2130.
A Vforward maximum (Vf_max) is found as described in section 2.3.3.2. AUTOMATIC POWER
SETTING. The Vf_max is compared to the maximal Vforward (Vf_max_tun) found when the Automatic
Power Setting was performed. When there is a certain difference (in dB) the step attenuator is controlled
accordingly.
As there is a certain compressing of the RF-signal in the Power Amplifier (1) a certain change (in dB) of
the Vf_max (due to a change in the battery voltage) will give a small change of the input RF-signal to the
Power Amplifier. This means that if the supply voltage has increased so much that the Vf_max is 0.6 dB
higher than the Vf_max found at the Automatic Power Setting, the RF-input level must be increased by
0.3 dB.
The number of steps (n3) the step attenuator has to be changed due to change in the supply voltage is
calculated in the following way:
(Vf_max_tun - Vf_max) / Vf_max_tun
n3 = -------------------------------------------------- (n3 can be negative,
10(0.6/20) - 1 zero, or positive).
In order to prevent fast oscillating in the automatic control of the step attenuator a decrease of the step
due to higher battery voltage is delayed a few seconds.
2.3.3.5 CALIBRATION OF THE T2130
In practice the calibration is done by means of a Service Programme. Please refer to the Service
Programmes. In the following the calibration is described functional.
MOTIVE FOR THE CALIBRATION
The calibration is done in order to eliminate tolerances in specific components related to the measuring
of the battery voltage and the Vforward voltage.
PRINCIPLES FOR THE CALIBRATION
The principle for the calibration is as follows. With a given battery supply voltage the RF-output is
increased until a specific distortion is reached. The battery voltage and the corresponding Vforward are
measured and the differences between the measured and the nominal values are calculated.
NECESSARY SIGNALS AND PARAMETERS
- Vbattery. This is measured by the TX-processor (3). The technique used by the TX-processor to
measure the 24 Volt battery is discussed in a separate subsection below.
- Vforward. This is measured by the TX-processor (3).
- Nominal values. This covers the coherence between the battery supply voltage and the maximum
allowable Vforward. For the description of the graph please refer to the subsection ‘Calculating
Vforward maximum’ in section 2.3.3.2. AUTOMATIC POWER SETTING.
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