Crescend Technologies DSDTUL50 User Manual

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Mobile Power Amplifiers DSDTUL50 and DSDTUH50.

User Manual.

1. Unit Description.

The power amplifier (PA) is nonlinear AB to C class unit that is intended for frequency (phase) modulated
(manipulated) signals amplification.

PA has the by-pass chain. If RF power, applied to the connector “XCVR” (Pin), is less than 50 mW, PA stays in
bypass (RX) mode. When Pin exceeds 0.15 W, PA switches to TX (amplification) mode. Unit returns to RX
mode in the case of overheat (when the heatsink temperature becomes +85ºC or greater).

PA has the automatic power control loop, which keeps the output power at the rated level. It reduces this level,
when the load VSWR is above 2.

The general parameters of unit are listed below. The term nominal means the nominal power supply voltage and
the heatsink temperature close to room temperature.

Frequency ranges of operation (F), MHz . . . . . . . . . . . . . . .. 406.1-470 (UL), 450-512 (UH);

Input power (Pin), W . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 - 5;

Output power at the normal operation (Pout-n), W, not less than . . . . . . . . . . . . . . . . . . 50;

Relative harmonic level, dB, less than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -70;

DC power supply voltage (Sup), V:

- nominal . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13.8;

- continuous, allowed . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 10.5 – 17.0;

- pulse, not longer than 30 ms and on/off ratio less than 0.1 . . . . . . . . . . . . . . . . . . 40;

Reversed polarity DC voltage acting, ms, not longer than . . . . . . . . . . . . . . . . . . . . . . . . 250;

DC current, A, not greater than:

- in RX mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.001;

- in TX mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12;

Load VSWR, not greater than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.5;

Input VSWR, less than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.8;

Switching time between RX and TX mode, ms, not greater than . . . . . . . . . . . . . . . . . . . . 0.6;

Insertion loss in RX mode, dB, less than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.0;

Continuous transmit time, min, not greater than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3;

Duty cycle, %, not greater than . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30;

Operating temperature range, ºC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -30 to +60;

RF connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50 Ohm UHF (F);

DC connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . # 6-32 AWG screws.

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The unit is assembled in the chassis with heatsink, intended for conventional cooling (see Fig 2).

Unit dimensions are 2.7” x 6.75” x 7.65”.

2. Installation Guide.

Install the unit in one of two positions, showed in Fig. 2: horizontal (fins up) or vertical. The proper air access to
the unit shall be provided: no obstacle for air is allowed closer than 3” from heatsink. The place of installation
shall provide the ambient temperature between -30ºC and +60ºC.
Screws from # 10 to # 1/4-20 are recommended for unit fastening. See the fastening holes’ positions in Fig. 3.

Use copper wire # 10 or #12 AWG shall for connection to the car battery. Wires shall be crimped for making
ring terminals.

Connect the clamp “+ 13.8V” to the pole “+” of car battery. Use 30 A fuse for protection.
Connect the clamp “GND” to the pole “-” of car battery.

Use 50 Ohm coax cables with UHF (M) connectors for connecting to “XCVR” and “ANT” .
Connect the port “XCVR” to RF output of radio.
Connect the port “ANT” to antenna.