Olson Technology DSK-550 User Manual

DSK-550

FREQUENCY AGILE “DESKTOP” TELEVISION

MODULATOR

INSTRUCTION MANUAL

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025-000376 REV C 8/7/01

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DSK-550

Specifications

Output Frequency Range........................... Channel 2 (55.25MHz) through 547.25MHz. Selectable by front

panel DIP switch in 2MHz increments (250KHz internal adjust­ment)

F .C.C. Offset............................................... +12.5KHz tunable by front panel adjustment

Output Power Level ................................... +40dBmV minimum per channel

Frequency Accuracy / S tability .................. <±5KHz of selected channel frequency

Video Performance..................................... 1V P-P input nominal for 80% modulation. Differential gain <5%

Differential Phase <5°

Spurious Outputs ........................................ >60dB typical, 55dB below output visual carrier level

Out-of-Band C/N ........................................ >76dB as measured in a 4.0MHz noise bandwidth

In-Band C/N ............................................... >60dB as measured in a 4.0MHz noise bandwidth

Audio / Video Ratio .................................... Adjustable from 13dB to20dB below video carrier

Audio Performance..................................... 500mV P-P for 25KHz deviation, front panel adjustable.

10K input Z

Audio Intercarrier S tability ........................ 4.5MHz within ±1KHz

BTSC Ster eo / Mono.................................. Internal defeat of audio pre-emphasis for BTSC baseband inputs.

Shipped mono mode

Front Panel Controls .................................. RF output adjust

A/V ratio adjust
V ideo & Audio modulation
F .C.C. offset adjust
Channel select DIP switches

Rear Panel Connectors .............................. RCA type video/audio input

T ype F RF output

Power Consumption.................................... <12 watts

Chassis Size ................................................ 2”H x 6.75W x 5.75D

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1.) INTRODUCTION

The Olson T echnology DSK-550 is a frequency agile F .C.C. compatible modulator in a 5 ¾”D x 6 ¾”W x
2”H desktop chassis. The DSK-550 may be operated at 45dBmV typical, +40dBmV guaranteed mini­mum. No IF loops are provided on this modulator .

The DSK-550 modulator will operate on any standard, or cable channel from 55.25MHz – 547.25MHz.
All channels are selectable by front panel DIP switches and a front panel adjustment allows setting to F .C.C.
offset frequencies, HRC frequencies are available.

The DSK-550 features >76dB out-of-band C/N ratio. SA W filtering is used for adjacent channel operation
and provides 55dB of spurious free dynamic range.

The DSK-550 has low power consumption for economical and reliable long-term operation.

DSK-550

Frequency Agile T elevision Modulator

2.) CHANNEL SELECTION

Channel frequencies are selected by setting the 10-position DIP switch (visible through the vertical slot in the
front panel). The front panel is illustrated in figure 1.

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Switch-setting codes for sub-band channels are shown in T able 1. Switch-setting codes for standard
channel frequencies can be found in T able 2 in this manual, HRC code settings are shown on T able 3. The
front panel illustration in Figure 1 shows a switch properly set for Channel 2.

3.) F .C.C. OFFSET ADJUSTMENT

F .C.C. Offset frequencies are shown in T able 4. T o adjust the frequency of a selected channel to provide
the correct F .C.C. offset, look up its offset frequency in T able 4. Remove the video input and connect a
counter to the RF output of the DSK-550. Use the front panel offset adjust control to set the output
frequency to the correct value.

4.) REAR P ANEL

The rear panel of each module has its audio and video inputs and its RF output.
The audio and video inputs are RCA type phono jacks and the RF output is a type “F”.

Figure 1 – DSK-550 Front Panel

5.) VIDEO MODULA TION ADJUSTMENT (Each modulator).

DSK-550 modulator modules are preset at the factory for 85% depth of modulation with a 1V P-P pulse
and bar test signal. If the video modulation needs to be adjusted, follow the procedure below .

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