Hameg HM5014-2 Service Manual page 18

3 . A d j u s t m e n t
TR-ROT screen, and there compare which setting is best, and
switch off again before next setting.
Select item „INTENS" in the internal adjustment menu as de-
scribed in section 2.2.1. The same screen contents as above will
appear. Observe the voltage reading shown on upper right part
of CRT. Adjust this value to 1.50 volts using the rotary encoder.
Then select item „FOCUS" in the internal adjustment menu
as described in section 2.2.1. Again, the screen contents will
be the same as described above. Adjust for best focus of the
center cross on CRT. Using the reduced intensity just chosen,
the focus will give a very precisely defi ned rendering of the 2
center cross lines.
Select item „INTENS" in the internal adjustment menu as de-
scribed in section 2.2.1. Use the rotary encoder to adjust the
intensity voltage value on the CRT to the maximun value of 5.10
volts. Check that the 2 center cross lines still have the same
width and are not out of focus, equalling or being a fraction
less in width compared to the width of the outer rectangle
lines. Adjust P3 on CPU-board for best representation of fo-
cus at full intensity. P6 is preset at the factory and does not
need to be touched.
3.2.4 Adjustment of Dot-Join
Select item „TR-ROT" in the internal adjustment menu as de-
scribed in section 2.2.1. A set of 6 lines will appear on the CRT,
forming a rectangle and a center cross. Also shown is a verti-
cal line 1.5 cm from the right vertical side line, which is 6 cm
large and has highlighted points at each end.
The upper end point of the single vertical line is about half as
bright as the lower end point. Check that both points occupy
a small area only. The lower end point is in the form of a hori-
zontal line of about 1 millimetre of length.
Adjust this vertical line for best representation using P1 for X
adjustment and P4 for Y adjustment. Both are located on CPU-
board (see Fig. 3-5)
After adjustment, the representation of the CRT should look
like the screen in Fig. 2-2. Swith off the unit to leave the ad-
justment menu.
3.2.5 Adjustment of TCXO and 3rd LO
The checking of TCXO (temperature compensated crystal oscil-
lator) frequency is extremely critical because it depends lar-
gely on the correct period of warmup with casing on the unit.
Incorrect temperature during checking will lead to possibly
incorrect values of TCXO frequency.
Set the HM5014-2 to the following:
RBW 1 MHz
Center 500 MHz
Span Zero Span
Ref.-Level -20dBm
ATT 10 dB
(Max Hold, Average,Video fi lter, Marker and Tracking Ge-
nerator not activated)
Connect a 500 MHz, -30 dBm signal (unmodulated) to the RF
input of the HM5014-2, as shown in measurement setup 1.
Unplug the SMB connector [CiC2] underneath the RFC
board gently with a pair of pliers[A6]. Then connect it via an
adaptor[M6] and a coaxial cable [M8] to the "A" input of the
frequency counter, as shown in measurement setup 2 (using
option "B" connection of the HM5014-2) (see Fig. 3-4).
18
Subject to change without notice
Figure 3-6: Illustration of CiC2 connector
The frequency indicated on the frequency counter should be
29.300000 MHz, a deviation of ±10 Hz is permissible. Choose a gate
time of 2 seconds or greater for exact results. To adjust the fre-
quency, open the cover of the CPU-board (see Fig. 3-5) by remo-
ving the 7 countersunk screws indicated, then remove the screw
left over to open the cover on the right side of the CPU-board
(as seen from the front), remove the protective label, and use a
ceramic screwdriver [A1] or [A2] (depends on slot type) to adjust
the frequency to 29.300000 MHz ±2Hz. Place a new label on the
tuning hole of the TCXO. Close the cover of the TCXO part again,
then replace the CPU-board cover. Fit all screws in place.
Now reconnect the SMB plug [CiC2] to the RFC board. Then
unplug the SMB plug from the IFA-Board, and connect it via
an adaptor[M6] and a coaxial cable [M8] to the "A" input of the
frequency counter, as shown in measurement setup II (using
option "C" connection of the HM5014-2).
The frequency indicated on the frequency counter should be
10.700000 MHz, a deviation of ±15 Hz is permissible. Choose a
gate time of 2 seconds or greater for exact results. To adjust
the frequency, open the cover of the RFC box (the smaller box
in IF-unit) and use a ceramic screwdriver to adjust the frequen-
cy to 10.700000 Hz ±5 Hz (keeping in mind a possible deviation
introduced by the TCXO). Close the cover of RFC box and fi x it
with the screw.
3.2.6 Check of Amplitude adjustment
In order to check the amplitude adjustment, set the HM5014-2
to the following using measurement setup 1:
RBW 1 MHz
Center 500 MHz
Span Zero Span
Ref.-Level -20 dBm
ATT 10 dB
Scale 10 dB/Div
Marker active
(Max Hold, Average, Video fi lter and Tracking Generator not
activated)
The synthesizer is set to the following:
Frequency 500 MHz
Amplitude -20 dBm
Output On
Modulation Off
Sweep Off
Now check that the level displayed is not more than 1 dB diffe-
rent than the level shown on the synthesizer when varying the