Philips PM5324 Instruction Manual page 17

16
- 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 AMPL ITUDE.
- Adjust the width of the ba nd-pass curve with potentiometer SWEEP W IDTH.
- Check the band-pass curve; if necessary, correct it. Th e effect of an adjust ment can
immediately on the ba nd-pass curve.
Note
When using harmonics the frequency sweep is multiplied by the order number of the h armonics.
Deter mining ,he band width
Sy defined shifting in the h orizontal directio n the band width (at
determined as follows:
- Position the point of intersection, e.g. of the right edge of the band-pass curve and a fictitions h orizontal
%
line at 70 of the height of the curve on a prominent point on the graticule by m eans of potentiometer
FREQUENCY.
- Read the frequency at the scale and note the value.
- S hift the band-pass curve horizontally with potentiometer FREQUENCY so that the second edge is
positioned at the same fictitions point of intersection (at
adjustment.
- Read the frequency; the difference between the two frequencies is the band width.
Note
Use a d.c. indicator (oscilloscope or m eter) so that the base line is horizontal and undistorted at a large
wobbulati ng-sweep.
2. 2.4.5. Calibration
The calibration points are indicated on the scale by the symbol
illuminated at calibration mode, serves as indicator.
Checking
If a very accurate HF-signal, e.g. of 21.5 M H z is needed, this can be checked as follows :
- Switch on the instrument and wait at least
- Depress range-button
- Depress button CA L.; the indicator will light up. If necessary, unlock button
- Set the scale pointer to t h at calibration mar k
- 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 m ar k calibrate as follows:
- Set the scale pointer exactly on the calibration mark.
- Hold the largest knob of control FREQUENCY with one h a nd.
- Adjust the s maller 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 m ar k. Repeat the calibration procedure,
if necessary.
2.2.4.6. 1 kHz-Generator
- Release all push-buttons, especially button
- The 1 k Hz-sign al, with an amplitu de of 2 V
minutes for it to warm up.
30
10 - 30 M Hz; the diode alongside the top scale will light up.
( Y
at mark .2) wh ich is nearest to the nominal value of 21.5 M H z.
was.
is availi) ble at SNC-c onnec tor 1 k Hz/SW EEP OUT.
. •
r.m.s
be d etermined
70 %
of the h eight of the picture) can be
70 %
of the height of the picture) as in the first
Y
or}. . A moving coil meter, which is
was ..