Olson Technology LCM-550x1 User Manual

LCM-550x12

SERIES

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Section I: Modulators

1. LCM-550x1

2. LCM-550x1 PAL I

3. LCM-550x1 P AL BG

Section II: Demodulators

1. LCD-550x1

4. LCD-550x1 P AL D/K

Section III: Amplifiers

1. LCX12-AMP

Section IV : Combiners

LCM-550x12 Series

1. LCM-550-FAC

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LCM-550x12

12 CHANNEL TELEVISION MODULATOR SYSTEM

INSTRUCTION MANUAL

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025-000329 REV C 6/1/01

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LCM-550x12

Frequency Agile Modulator System

Specifications

Output Frequency Range: 55.25 to 547.25MHz in 2MHz increments, selected by front panel

DIP switch. 250KHz increments internally selectable for HRC
frequencies.

Output Power: +40dBmV minimum, +45dBmV typical per channel. Downward

adjustable by 10dB minimum.

Spurious Outputs: >60dB below output video carrier out of band.

Out-of-Band C/N: >80dB below output video carrier (4MHz bandwidth) - per channel.

In-Band C/N: >57dB

Frequency Stability/Accuracy: Designed to meet F.C.C. title 47 part 76 (+10 Celsius to + 40 Cel-

sius). Offset adjustable by front panel potentiometer .

Audio/Video Ratio Adjust: From 13dB to 20dB below video carrier. Adjustable by front panel

potentiometer.

Audio Intercarrier Accuracy: 4.5MHz +/- 1KHz

Video Input: 1V P-P nominal for 85% modulation. Front panel adjustable, from as

low as 0.5V P-P input. 75 Ohm input Z utilizing an RCA connector.

Audio Input: 500mV P-P for 25KHz deviation. Adjustable by front panel potenti-

ometer. 10K input Z utilizing an RCA connector.

Power Requirements: 85 - 264VAC, 47 - 63Hz, 60 Watts maximum.

Size: 3.5”H x 19”W x 11”D (Rack Mount Chassis)

Weight: 10 LBS.

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12 CHANNEL, FREQUENCY AGILE - F.C.C. COMPATIBLE

1.) INTRODUCTION

The Olson T echnology LCM-550X12 can consist of twelve frequency agile F .C.C. compatible television
modulators in a single 3 ½” rack – mount chassis. The LCM-550X12 has a separate RF output for
each channel, and each channel may be operated at +45dBmV typical, +40dBmV guaranteed mini­mum. The LCM-550X12 modulator is compatible with baseband scrambling techniques. No I.F .
loops are provided on these modulators.

Each of the twelve modulators will operate on any standard or cable channel from 55.25MHz to

547.25MHz (VHF channels 2 through 13 and cable channels 14 through 78). All channels are select­able by front panel DIP switches and a front panel adjustment allows setting to F .C.C. of fset
frequencies. HRC frequencies are available.

LCM-550x12

TELEVISION MODULA TOR SYSTEM

Each of the modulators in the LCM-550X12 offers the unique Olson Technology feature of >80dB
out-of-band carrier to noise ratio. These units use SAW filtering for adjacent channel operation, and
provide 60dB of spurious free dynamic range. These features allow virtually unlimited numbers of
LCM-550X12’s to be combined without the need for external bandpass filters.

The LCM-550X12 has low power consumption (approximately 5 watts per channel @ 115 VAC) for
economical and reliable long term operation.

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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.

Channel Select

Figure 1 – LCM-550 Front Panel

Switch-setting codes for standard channels are shown in Figure 2 and on the code card provided with the
system. Switch-setting codes for HRC channel frequencies can be found in T able 2 and Figure 3 in this
manual. The front panel illustration in Figure 1 shows a switch properly set for standard channel 2.

3.) F.C.C. OFFSET ADJUSTMENT

F.C.C. Offset frequencies are shown in Table 1 and summarized on the code card provided with the
system. To adjust the frequency of a selected channel to provide the correct F.C.C. offset, look up its
offset frequency in Table 1 (or use the summary on the code card). Remove the video input and
connect a counter to the RF output of the LCM-550. Use the front panel offset adjust control to set
the output frequency to the correct value.

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Figure 2 - CHANNEL SWITCH SETTING CODES

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TABLE 1 F.C.C. OFFSET FREQUENCIES

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TABLE 2 HRC CHANNEL CODES

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TABLE 2 CONTINUED. HRC CHANNEL CODES

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Figure - 3 INTERNAL SW2 SETTINGS FOR HRC / STD

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4.) REAR PANEL

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”.

5.) VIDEO MODULATION ADJUSTMENT (Each modulator).

LCM-550X12 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.

Connect the video source (to be used at approximately 1V P-P) to the video input phono jack. The video should be of a
reasonably bright scene (commercials are usually excellent).

Adjust the video modulation control on the front panel to obtain approximately 85% depth-of modulation as measured
on a spectrum analyzer or other test equipment capable of this measurement.

If the video modulation control needs to be set and there is no test equipment available, it can be set fairly close by
comparison. View a video signal on a properly adjusted television receiver or receiver/monitor. Apply the same signal
if possible, or one of equivalent brightness and contrast to the modulator that needs to be set. View the output of this
modulator on the same receiver and adjust the video modulation control for brightness and contrast equivalent to the
directly viewed picture. Use caution and do not set this control too high.

6.) AUDIO MODULATION ADJUSTMENT (Each modulator).

Connect the audio source (to be used at approximately 500mV P-P) to the audio input phono jack.

Monitor the audio on a television receiver and adjust the audio modulation control for proper loudness as compared
with some channel known to be modulating at the correct level (such as a broadcast station).

The two sources of audio should be very similar in their content and should be near maximum loudness as compared to
the average level of their program. In other words, compare a loud passage with a loud passage and set the audio
modulation control with this program material. Use caution and do not set this control too high.

7.) OPERATION WITH COMPOSITE BASEBAND BTSC AUDIO INPUT (Each modulator).

The LCM-550X12 modulators are compatible with a composite baseband BTSC audio input. An internal jumper must
be changed to remove audio pre-emphasis as required for this application.

To remove audio pre-emphasis, disconnect and remove the LCM-550 module from the main shelf and remove its left
side cover. Cut board where indicated.

Replace the module cover, replace the module in the main shelf, and set-up the audio deviation per the instructions for
the BTSC generator being used.

8.) RF OUTPUT AND AURAL CARRIER LEVEL ADJUSTMENT (Each modulator).

A) Using a field strength meter or spectrum analyzer, set the video carrier to the desired level with the output level

(RF) control (typically +40 to +45dBmV).

B) Tune the field strength meter to the aural carrier, which is located 4.5 MHz above the video carrier.

C) Adjust the aural carrier level control (A\V) to the desired level, typically 15dB below the video carrier.

CAUTION: Reducing the aural \ visual carrier ratio to less than 15dB can result in high out-of-band spurious
signals on adjacent channels.

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9.) MISCELLANEOUS

A) The front panel adjustments (RF, OFFSET, etc.) are small, and somewhat delicate. Use CAUTION and an

adjustment tool that is a proper fit when adjusting these controls.

B) The LCM-550X12 is BTSC stereo compatible. Each modulator is shipped in the “mono” mode. To defeat the

pre-emphasis in order to use a composite baseband BTSC input signal, see section 7 of this manual.

C) The LCM-550X12 power supply is equipped with an internal 3Amp. 250V GMA fuse. For continued safety, and

to maintain proper performance of the unit, please replace only with an equivalent fuse.

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LCM-550X12

PAL I ADDENDUM

INSTRUCTION MANUAL

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025-370312 REV B 8/2/01

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LCM-550X12

PAL I

Specifications

Output Frequency Range ........................... 48.25MHz to 551.25MHz. Selectable by front panel DIP switch in

2MHz increments (250KHz internal adjustment)

Frequency Offset ........................................ +12.5KHz tunable by front panel adjustment

Output Power Level ................................... +40dBmV minimum per channel, +45dBmV typical

Frequency Accuracy / Stability .................. <±5KHz of selected channel frequency (+10°C to +40°C)

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

Differential Phase <5°

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

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 50KHz deviation, front panel adjustable.10K input Z

Audio Intercarrier Stability ........................ 6.0MHz within ±1KHz

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

A/V ratio adjust
Video & Audio modulation
Frequency offset adjust
Channel select DIP switches

Power Requirements .................................. 85-264VAC, 47-63Hz, 72 watts

Chassis Size ............................................... 3.5”H x 19”W x 11”D (Rack mount chassis)

025-370312 REV B

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