User's Manual

P-379 Processor

8. While the RF OUTPUT signal is still connected to the spectrum analyzer or field

strength meter, observe the aural carrier level. The difference between the video

carrier level and the audio carrier level – the “Delta AV” or ΔAV – should be the

same as the input source. In other words, if the RF INPUT signal ΔAV is 13dB,

the RF OUTPUT signal ΔAV should be 13dB ±2dB. Minor adjustment of this

ΔAV may be made either at the input signal source (if the input signal is not from

an off-air source) or with the AURAL CARRIER LEVEL control on the front panel

of the P-379. When switching to either of the frequency sources (STD or HRC),

the internal aural carrier attenuator drops automatically from 6dB to 0dB since

the ΔAV for cable signals has normally been preset at the headend. However,

the ΔAV for off-air signals may vary considerably. Normal operation level of the

aural carrier is 10 to 13dB below the video carrier. If adjustment of the AURAL

CARRIER LEVEL control on the front panel of the P-379 will not bring the ΔAV of

an off-air signal into an acceptable range, check the ΔAV of the input signal. If

the ΔAV of the input signal is too small or is negative (the aural carrier is above

the video carrier), it is possible that the AURAL CARRIER LEVEL control of the

P-379 will be unable to compensate. Check the input signal before contacting

Technalogix for return-for-repair information.