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6 installation – Drake 300VMF+ Fixed Modulator User Manual

Page 6

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6 Installation

CONNECTIONS AND CONTROLS

All connections to and from the 300VMF+ are made through

the rear panel. Figure 4 shows a typical two channel

installation using a typical satellite receiver as a signal

source. Additional channels can be added by using

additional 300VMF+ modulators and either multi-port

combiners or combinations of two-port combiners.

INSTALLATION NOTES

Level adjustment provides optimum performance in

multichannel installations. The modulator outputs should be

checked periodically with a spectrum analyzer to maintain a

±1 dB variation of adjacent channel carriers. Aural/Visual

(A/V) ratios should be held to -15 dB or less.

The ‘RF Output Level’ and ‘A/V Ratio’ controls are used

respectively to make these adjustments. If an output level

of less than +43 dBmV is required, add an attenuator of the

appropriate value to the modulator output.

Example:

For an output level of +35 dBmV, add a 12 dB

attenuator pad to the modulator output and set the output

level.

RACK MOUNTING

Adequate ventilation is very important in multichannel

installations. Units should be spaced apart by at least one

panel height wherever possible, and some air movement is

advisable in enclosed rack cabinets. Excessive heat will

shorten component life and modulator performance will be

degraded without proper cooling.