Overview
Bext XT50, 50 Watt Exciter/Transmitter
- 50 W in ultra slim size, one rack space, stainless steel enclosure & excellent audio specs
- Fast access to programmability, functions & all readings from front panel via user-friendly menu display
- Built-in, selectable, very high separation internal Stereo Generator and Fast Audio Clipper, standard
- Full Telemetry & Remote Control connection through DB 15 port (rear panel), standard
- Full Telemetry & Remote Control connection through DB 15 port (rear panel), standard
- RS 232 interface through DB 9 (front panel), standard
- Instant user programmability allowing for ideal backup to multiple stations, standard
- Programmable FSK ID Keyer by software for auto-ID of translators, standard
- Proportional Auto-Foldback of output power in the event of excessive VSWR
- Adjustable power output from 0.1 W to full power, with soft-start control
- Automatic power control maintaining the set output at any pre-set level
- Connections for external power control loop to maintain pre-set power level of external amplifier
- Modular layout with plug-in, easily replaceable circuits and parts
- Includes low pass/harmonic filter and can be used as a stand-alone transmitter
- Meets or exceeds all FCC and CCIR requirements
Specifications
RF Specifications
Nominal RF Output Power: 50 W, adjustable from approximately 0.1 W to Full Power RF output
impedance: 50 unbalanced, VSWR less than 1.5:1
RF connector: Type N female
Frequency range: 87.5 – 108 MHz, front panel programmable in 10 kHz steps, synthesized, microprocessor controlled
Off-lock attenuation:> 60 dBc
Lock-in time: typ. 7 sec
Type of modulation:F3E / F8E direct FM at carrier frequency
Frequency deviation: ±75 kHz =100 %, ±150 kHz capability
Reference: 10 MHz TCXO Stability of freq. dev: ±2,5 % x 6 months
Consistency of deviation over range: < ± 2% from 87.5 to 108 MHz
Frequency drift: 1 kHz/year (due to internal TCXO aging). Can be user-calibrated
Short term stability: ± 1 ppm from -5 to +45 C (100 Hz @ 100MHz)
RF Harmonics: Exceeds EBU/CCIR/FCC requirements < -70dBc
RF Spurious: Exceeds EBU/ CCIR/FCC requirements, < -100dBc min @ ±1 MHz
Audio General Specs
Preemphasis: selectable Flat / 50 / 75 micros.
Preemphasis Precision: better than ± 0.5 dB
Wideband Amplitude Response: ± 0.2 dB 30Hz to 53KHz; ± 0.2 dB 53KHz to 100 KHz
Wideband AM Asynchronous: (FM = no modulation, Ref. = 100% AM, Unweighted, RMS detector, BW 30-200 kHz) < -68dB, typ. -80dB
Wideband Distortion, THD: < 0.1% (typ. 0.05%)
WB Distortion, IMD: < 0.1% (typ. 0.05%)
WB Transient IMD:< 0.25% (square/sine wave)
Composite & Mono Specs
S/N: Typical Values referred to ± 75kHz: Weighted (CCIR 468/2 – Peak CCIR detector) – 75 dB / 50s – 69 dB / flat; Weighted (CCIR 468/2 – RMS detector) – 79dB / 50s -72dB / flat; Unweighted (RMS detector, meas. 20Hz-23kHz) – 86 dB / 50s – 80 dB / flat (stereo); Unweighted (RMS detector, meas. 20Hz-23kHz) – 92 dB / 50s – 88 dB / flat (mono)
IMD: 70 Hz / 6 kHz 4:1 RATIO 0.03% measured with 1 kHz and 1.3 kHz tones, 1:1 ratio @ 75 kHz deviation
Transient IM: 0.03 % (square/sine)
Audio response: .15 dB 20 Hz to 15 kHz
AM Synchronous: (AM = 400 Hz, FM = 400 Hz 75 kHz Ref. = 100 % AM , RMS detector, meas. 20Hz-23kHz ) < -69 dB
AM Asynchronous: FM = no modulation, Ref. = 100 % AM, Unweighted, RMS detector, meas. 20Hz-23kHz ) < -70dB (typ. -85dB)
Common mode rejection: 45 dB typical, 25 Hz to 15kHz
Built-in Stereo Gen. Specs
Stereo System: EBU/CCIR/FCC standard ‘Pilot Tone System’
Pilot Tone Frequency: 19 kHz 1 Hz
Pilot Tone Deviation: 7 kHz nominal
38 kHz Suppression: 70 dB (typ. 85 dB)
38 kHz Tone Generation: Internal Crystal
38 kHz Tone Precision: 38 kHz 2 Hz
Phase response: 19/38 kHz internally adjustable
Stereo Separation: 30-80Hz >53dB, 80Hz-15kHz >60 dB Crosstalk attn. (M / S): 40 dB, 40 Hz to 15 kHz (typ. 55dB, 100Hz to 8kHz)
Audio Spurious Products: 53 kHz < 50 dB THD on L & R channels: 0.03%, 30Hz-15 kHz
Audio Filter Attenuation: 55 dB @ 19 kHz; >45dB 19 to 50 kHz; > 50dB to 100kHz (typ.)
Audio Inputs
Composite/MPX Input: 1 BNC connector, unbalanced, 50 600 switchable.
Input level range for 75 kHz Deviation: -13 to +13 dBm, adjustable on rear panel SCA / RDS / AUX Inputs: 2 BNC connectors, unbalanced, 10 k Input level range: -20 to +13 dBm for 7.5 kHz, adjustable on rear panel
L&R + Mono Input: 2 XLR connectors, balanced or unbalanced; switchable 50 600 . Input level range for 75 kHz Deviation: -13 to +13 dBm, adjustable on rear panel
AES-EBU input (optional): XLR connector
Other Connectors
19 kHz Output: 1 BNC connector, unbalanced, 4.7k Pilot tone 1 Vpp 19 kHz Squarewave
DB 15: for Telemetry, including readings of RF forward and reflected power, PA Voltage, PA Current, Remote Control (including momentary contacts for on/off), Status of Correct Output (aka ‘PWR Good’), ‘RF Off’ Interlock (Normally Open) Additional “RF Off”
Interlock: BNC (Normally Open)
RS 232 Interface: DB 9 (on front panel).
RF Monitor (not suitable for measuring harmonics): -30dBc ±3dB, 50 BNC (on front panel)
Environmental
Storage temperature: -20°C to + 60 °C
Operating temperature: -10°C to + 50°C
Relative humidity: 90 % (non condensing)
Max operating altitude: 2000 m.
Max ambient field strength: ≤10 V/m; ≤ 4 A/m
Cooling: Forced air (internal blower)
Physical & Electrical
Front panel: 483 mm (19″) W x 44 mm (1¾”) H (One standard rack space high) Cabinet depth from front panel: 393mm (15½”) Total depth including front handles: 420mm (16½”)
Cabinet: Stainless steel
ApproximateWeight: 13 lbs (5,8 Kg)
Approx. Packed Weight: 19 lbs (8.6 Kg)
AC Power Requirement: Single phase 120 / 220V [±15%] 50 / 60Hz, extended range input
Approx. Power Consumption @Full Pwr: 75 VA
LCD Display Readings: Forward Power, Reflected Power, Frequency of Operation, Audio Presence, Deviation, Audio Input Selection, Audio Impedance, Preemphasis Status, Stereo Generator Enabled / Disabled, Audio Clipper Enabled / Disabled, L & R Channels Modulation Level, VPA, IPA, Temperature, Efficiency, Status of FSK ID Keyer, other misc. readings & functions.
