User's Manual

TM-200 Issue 1.02 November 2005 Page 5 of 64

3.0

ESCRIPTION AND

PECIFICATIONS

General Description

The TM-200 is a high output modulator that eliminates the need for preamplifiers prior to

the power amplifier system. The modulator first 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.

Pre-correction is implemented at IF frequencies with a Signal Conditioning Board.

Frequency conversion circuitry then translates the modulator’s IF carriers to VHF and

UHF television frequencies. All operating controls are located on the front panel, and

will be discussed in later section, while input and output interfaces are on the back plate.

An aural loop through is provided to properly set transmitter power.

Standard Features

• Totally microprocessor controlled with self-diagnostic monitoring.

• Selectable output channels:

 Standard Broadcast VHF 2 – 13, UHF 14 – 60, T7 – T13

 HRC channels 1 through 118

 ±10 kHz offsets

• SAW filtered IF designed for adjacent channel operation.

• + 10 dBm (minimum) output using low distortion hybrid amplifiers.

• Synthesized oscillators – crystal referenced phase locked.

• Bar graph modulation and digital LED readout.

• Internal switch selects standard or HRC output.

• Surface mount technology construction.

• RF muted during tuning.

• Optional aural sub-carrier and baseband audio input

• Phase lock loop FM audio.

• BTSC stereo compatible.

• External separate audio/video and composite IF loop-through.

• RS-232 control option

• Sound carrier level adjustable –10 dB to –15 dB.

• Video delay pre-distortion network meets FCC 73.687.

• High stability TCXO, ± 250 Hz

• Non-volatile memory retains channel selection after power loss.

• Video Detection turns off carrier in event of loss of video.

• IF pre-correction allow slope/knee linearization of signal.

• Sync level adjustment to ensure sync tip at proper levels.

• White clip and DC restoration of baseband video signal.

• 50-ohm RF Output and tap-off