Khz-Generator - Philips PM5324 Operating Manual

14
- Set the band-pass curve at the middle of the picture with potentiometer FREQUENCY.
- Adjust the height of the band-pass curve with potentiometer HF AMPLITUDE.
- Adjust the width of the band-pass curve with potentiometer SWEEP WIDTH.
- Check the band-pass curve; if necessary, correct it. The effect of an adjustment can be determined
immediately on the band-pass curve.
Note
When using harmonics the frequency sweep is multiplied by the order number of the harmonics.
Determining the band width
By defined shifting in the horizontal direction the band width (at 70
%
of the height of the picture) can be
determined as follows:
- Position the point of intersection, e.g. of the right edge of the band-pass curve and a fictitions horizontal
line at 70 % of the height of the curve on a prominent point on the graticule by means of potentiometer
FREQUENCY.
- Read the frequency at the scale and note the value.
- Shift the band-pass curve horizontally with potentiometer FREQUENCY so that the second edge is
positioned at the same flctitions point of intersection (at 70 % of the height of the picture) as in the first
adjustment.
- Read the frequency; the difference between the two frequencies is the band width.
Note
Use a d.c. indicator (oscilloscope or meter) so that the base line is horizontal and undistorted at a large
wobbu Iati ng-sweep.
2.2.4.5. Calibration
The calibration points are indicated on the scale by the symbol
Y
or
A .
A moving coil meter, which is
illuminated at calibration mode, serves as indicator.
Checking
If a very accurate HF-signal, e.g. of 21.5 MHz is needed, this can be checked as follows:
- Switch on the instrument and wait at least 30 minutes for it to warm up.
- Depress range-button 10 - 30 MHz; the diode alongside the top scale will light up.
- Depress button CAL.; the indicator will light up. If necessary, unlock button WOB..
- Set the scale pointer to that calibration mark ( V at mark .2) which is nearest to the nominal value of 21.5 MHz.
- Set the scale pointer exactly on the minimum which lies between two full-scale deflections of the indicator.
- Check, that the line of the scale pointer corresponds to the calibration mark.
Calibration
If the line of the scale pointer is not exactly over the calibration mark calibrate as follows:
- Set the scale pointer exactly on the calibration mark.
- Hold the largest knob of control FREQUENCY with one hand.
- Adjust the smaller knob - against the resistance of the slipping clutch - to obtain the required minimum
(zero beat) between two maxima.
- Release the large button.
- Adjust for exact zero beat.
- Check that the line of the scale pointer corresponds to tHe calibration mark. Repeat the calibration procedure,
if necessary.
2.2.4.6. 1 kHz-Generator
- Release all push-buttons, especially button WOB.
- The 1 kHz-signal, with an amplitude of 2
Vr.m.s .•
is available at BNC-connector 1 kHz/SWEEP OUT.