STU 31

1 KW TV UHF S.S. TRANSMITTER

MOD. STU31

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 STU 31
GENERAL DESCRIPTION

The STU - 31 is a solid state LD-MOS 1 KW transmitter for TV broadcasting with

combined amplification process in the UHF band IV & V, from 470 to 860 MHz .The
equipment is fully compliant with the personnel safety requirements as specified in IEC
215 .The rack frame design is very suitable for an easy maintenance and service : each
unit can be easily removed and checked.

AUDIO
TV BAND 1000 W RF
INPUT
PA PASS
VIDEO EXCITER
OUTPUT
FILTER
INPUT

STU 31 SIMPLIFIED BLOCK DIAGRAM

EXCITER

The EXCITER stage is very flexible due to his modular plug-in design, enable combined
and split amplification process as well as adaptation to the various TV standards. All
routine on-air adjustment are made by commands from the front panel.

TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM TECHNOSYSTEM

RF MONITOR MONITOR MONITOR MONITOR MONITOR R.F.. MONITOR L.O. MONITOR

OUT I.F. I.F. I.F. I.F.

ON CARRIER ON CARRIER CARRIER CARR.LOSS LOCK

PREEMPH.OFF PREEMPH.OFF GR.DLY OFF AUTO ECONOMY
CODER LOCK WHITE CLIP POWER LIM. EXT. REF.
AGC
MONO VIDEO PRES.
STEREO CH1
MAN D.PH.
DUAL CH2
REMOTE REF. FREQ.
ADJ.
V.C. LVL
P.S. MEAS. VIDEO ALC
V.C. LVL SYNC.
HRS

PUSH

HRS

PUSH

S.C.1 LVL FWD PWR 1 1

S.C.2 LVL I.F. RFL PWR LVL LVL LVL 1
ICPM
DEV. S.C.1 TEMP
DEV. S.C.2 FAIL AUDIO AUDIO VIDEO MLC
IN IN IN
LIN.PREC. K1
LINE 2
2 2 K2
SELECT MODE OFFSET
HRS

PUSH

HRS

PUSH

LVL LVL LVL K3 ADJ.

OFF

S.C. LVL S.C. LVL

I.F. OUT IN I.F. OUT IN I.F. OUT IN I.F. OUT I.F. IN L.O. OUT L.O.
DISPLAY STEREO SOUND VISION A.L.C. UP LOCAL
CONTROL MODULATOR MODULATOR MODULATOR PRECORRECTOR CONVERTER OSCILLATOR

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 STU 31

POWER AMPLIFIER

The amplification is made up by a single RF PA (power amplifiers, SAU - 31), the

nominal output power is 1 KW p.s. The PA employs solid state LD-MOS technology, 4 RF
pallets and a driver, in order to obtain wide band , reliability , and high efficiency . The PA
has 4 built-in switch-mode power supplies, in order to have the maximum of redundancy,
self-protected against overcurrent , overvoltage and overtemperature , while the amplifier
has as well the overtemperature , VSWR for RF parameters.

COOLING SYSTEM

The transmitter is air cooled with forced ventilation performed by built-in high reliability
blowers. A careful and proper design has been adopted in order to guarantee all the power
devices to work safely even in very high temperature environments.

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 STU 31

STU31 - Technical Specifcations

RF
- Frequency range………………………. 470 to 860 MHz
- Output power………………………….. 1000 W peak sync
- Vision/Sound power ratio…………… 10/1 single sound or 20/1/0.2 dual sound
- Output-stage technology……………. solid state LD-MOS
- Vision-Sound amplification…………. combined
- Standards……………………………… G, K, I, M, N
- Modulation class……………………… C3F, F3E
- Sound transmission………………….. FM single-sound ( IRT or NICAM 728 )
- Harmonic and spurious emission…. ≤ 1 mW
- IMD products in band ≤ 60 dB
- Frequency stability…………………… ± 100 Hz / 1 month ± 1 Hz / month
- External reference frequency………. 5 MHz, 0.2 ÷ 1.0 V / 50 Ω
- Offset capability………………………. 10/25 Hz steps up to ± 25 kHz

TRANSMISSION CHARACTERISTICS
- Sideband spectrum response……. according to the standard G
- Amplitude-frequency response…… according to the standard G
- Group delay variation ……….……… ≤ ± 35 ns (without receiver precorrection
and sound trap in TV demod.)
- Non linearity distortion……………… ≤ 5%
(mod. 10 to 75%)
- Differential gain………………………. ≤ 5%
(mod. 10 to 75%)
- Differential phase…………………….. ≤ ± 2 degrees
(mod. 10 to 75%)
- Incidental carrier phase…………….. ± 3 degrees
modulation
- Signal to hum (peak value) ratio…… ≥ -48 dB
(f < 10 kHz)
- Signal to random noise……………… ≥ -56 dB
(unweighted 0.2 to 5 MHz)
- Blanking level variation……………… ≤ 2%
- 2T k factor……………………………… ≤ 2%
- ICPM (picture range)…………………. ≤ 2 degrees
- Intercarrier S/N ratio…………………. ≥ 46 dB (referred to ±50 kHz deviation)
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 STU 31

VISION
- Video input……………………………. 2 with aut. Switchover (BNC conn. 75 Ω )
- Colour systems…………………………. PAL / SECAM / NTSC
- Nominal input level…………………… 1 Vpp ± 6dB into 75 Ω
- Return loss…………………………….. ≥ 34 dB
- DC restoration…………………………. clamped to the blanking level without
affecting the burst
- White limiter…………………………… at 90% picture signal without affecting
the chrominance
SOUND
- Sound input……………………………. 2 with autom. Switchover (video master)
- Nominal input level…………………… +6 dBm ± 6dB (± 50kHz dev.)
- Input impedance………………………. 600 Ω balanced
- Pre-emphasis………………………….. 50 µ s (75 µ s on request)

METERING
- peak sync output power
- Reflected power
- Power supply status
- Temperature

PROTECTION CIRCUITS
- VSWR
- Air cooling loss
- Overtemperature
- Overcurrent

REMOTE CONTROL
- Parallel interface……………………… start, stop, alarm, interlock
- Serial interface………………………... RS 232

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 STU 31

GENERAL
- Mains voltage………………………….. 230 Vac + 10% -15%
Any other voltage available on request
- Mains frequency………………………. 47/63 Hz
- Temperature range…………………… 0 to +45°C
- Relative humidity……………………… 95% not condensing
- Altitude………………………………….. up to 2.500 meters
Higher altitude levels are possible on request

- Power consumption (50% APL)….. 2800 W

- Power factor…………………………… ≥ 0.9 (TYPICAL ≥ 0.95)

- Ambient dissipation………………….. < 150 W
- Air cooling……………………………… 600 m3/h

Dimensions (rack):
- Width……………………………………. 584 mm
- Height…………………………………… 1020 mm
- Depth……………………………………. 1200 mm

Weight:……………………………………. 120 Kg.

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 STU 31
STANDARD INSTALLATION REQUIREMENTS

TRANSMITTER ROOM
The building floor must be suitable to support a capacity :

≥ 300 kg / m2

INSTALLATION AREA
It must be clean and free of dust , the transmitter must be installed to have space
around enough for ventilation and for maintenance actions to be allowed.
The minimum requirement space for transmitter must be :

2 x 2 x 2 (H) meter

TEMPERATURE
Room temperature does not exceed :

0 to + 45 °C

ELECTRICAL PLANT
The main power installed must be :

≥ 5 kVA

MAIN VOLTAGE
The three-phase AC voltage must be :

Nominal value + 10 to –15 %

MAIN POWER CABLE SIZE (mm2)

Operation voltage Phase wires Neutral wire Protection earth wire

230 V ≥ 12 not used ≥ 16

AIR COOLING

The room must be capable of :

600 m3/ h air flow

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