TM150 Analog Modulator
The high output modulator eliminates the need for preamplifiers prior to the power amplifier system. The modulator processes baseband audio and video information to provide an IF output consisting of a visual IF carrier at 45.75 MHz, using amplitude modulation, and an aural IF carrier at 41.25 MHz, using frequency modulation. An internal upconverter translates the modulator circuitry's IF carriers to VHF and UHF television frequencies. All operating controls are located on the front panel. An aural loop through is provided to properly set transmitter power.
Standard Features
- Selectable output channels: Standard Broadcast VHF, UHF,
- SAW filtered IF designed for adjacent channel operation
- + 60 dBmV output using low distortion hybrid amplifiers
- Synthesized oscillators - crystal referenced phase locked
- Modulation LED readout
- Surface mount technology construction
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- Phase lock loop FM audio
- BTSC stereo compatible
- External separate audio/video and composite IF loop-through
- Aural carrier level adjustable -10 dB to - 15 dB
- Video delay predistortion network meets FCC 73.687
- High stability TCXO, + 250 Hz
- Non-volatile memory retains channel selection after power loss
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RF Characteristics
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Frequency Range
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7 to 750 MHz
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Frequency Response (one Channel)
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± 0.5 dB
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Frequency Stability
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± 250 Hz
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RF Output Level
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60 dBmV max
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Harmonics
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>60 dB below rated power
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Predominant Intermodulation Products
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dBc = decibels below visual carrier
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+920kHz
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>60 dBc
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-920kHz
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>60 dBc
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+2.66 MHz
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>60 dBc
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-2.66 MHz
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>60 dBc
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+5.42 MHz
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>60 dBc
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+7.16 MHz
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>60 dBc
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3rd Order Intermodulation Products
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-4.5 MHz
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>60 dBc
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+9.0 MHz
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>60 dBc
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All Others
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>60 dBc
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Spurious Emissions
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>-60 dBc
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NTSC Video Characteristics
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Input Level (for 87.5% modulation)
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1.0 Vpp
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Differential Phase (at 87.5% modulation)
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± 2 Degrees
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Differential Gain (at 87.5% modulation)
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2 %
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Group Delay
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< ± 40 ns
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K-Factor
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1.9% for 2T Pulse
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Hum and Noise
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> 60 dB below rated Power
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Aural Characteristics
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Input: 50 Hz – 15 KHz
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0 dBm (0.8V)
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Impedance
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600 ohms, balanced
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Frequency Response
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± 1 dB
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Frequency Tolerance, ± 500 Hz
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4.5 MHz
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Frequency Deviation
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± 25 KHz
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Harmonic Distortion
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1% max
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Preemphasis (mono) Internally Defeatable
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75ms
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IF Section
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Output Impedance
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75 ohms, unbalanced
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Video IF level
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+ 37 dBmV, +97 dBmV
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Audio IF level
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+ 22 dBmV, +82 dBmV
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Return Loss
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>14 dB
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Video Sound Spacing
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+ 4.5 MHz
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Vestigial side-band width
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0.05 MHz
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Second IF Frequency
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945.75 MHz
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These Specifications are subject to change without notice and may be altered to meet individual requirements.
