Wavetek SAM 3000 Operation Handbook page 17

may be easily compensated by calibrating the SAM 3000 at or near the
temperature at which it will be used. The convenient built-in calibrator makes
calibration a simple process.
To calibrate the SAM 3000, simply connect the calibrator output (Cal Out) to the
RF input (RF In) with a3 to4 foot jumper. Next, press "FCN", "CAL". The LCD
will show "CALIBRATION", and the meter will deflect to 10 dB below full scale.
When calibration is complete, the meter will return to normal operation, and the
meter is calibrated.
The calibrator is a precision 55.2 MHz oscillator, which is switched "on" when
the Cal function is implemented. The RF input is measured, and this measure-
ment is compared to the known calibrator level. The SAM 3000 is then
recalibrated to the known calibrator level.
The calibrator may be activated for use in other tests by pressing "FCN", "STAT"
"ENTER", This function is provided to enable quick tests of component loss and
isolation as described in the application section of this manual. To avoid possible
measurement procedure errors, the meter remains tuned to 55.250 MHz while
the calibrator is "on". This also ensures that the calibrator is not left "on"
accidentally, which would shorten battery life.
An MC-50 400 should not be used to check the SAM 3000' s peak detector.
(Peak detector operation may be verified by turning modulation on and off
to ensure that the meter reads both modulated and unmodulated signals
consistently and accurately). The SAM 3000 peak detector is designed to
measure horizontal sync suppression scrambled signals accurately, based
on the 60 Hz vertical interval, and for this reason doesn't read accurately
when the only modulation present is a simulated 15,750 Hz modulation.
How To Set-up Headend Levels
The SAM 3000 has two special features to improve headend alignment effi-
ciency: The Reference Level Function, and the Delta V - A Function (video/audio
carrier ratio). These features simplify the process of aligning the headend for a
flat output. The first step is to measure and adjust the channel 2 video carrier to
the desired amplitude. Next, press "FCN" "GAIN". This makes the channel 2
signal amplitude the reference for the other carriers, and all subsequent
measurements while in this mode will be "normalized" to the channel 2 carrier
amplitude. The display will show 0.0 dB, unless the signal amplitude changes.
You may now step through the channels using the up arrow key, and adjust each
modulator or processor until the level reads 0.0 dB. After this is done, all of the
video carriers will be aligned to the same level as the channel 2 video carrier, and
the audio carriers may be measured and adjusted as necessary. Press "CLR" to
return to normal operation.
To set the audio carriers, tune to channel 2 and press "FCN" "AV/A", The
difference between the channel 2 video carrier and the channel 2 audio carrier
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