B Final Alignment - Tuner; C Alignment - If-Unit - Hameg Instruments HM5011 Serviceanleitung

B Final Adjustment - Tuner
The tuner is already aligned by the factory. When changing the 1st mixer, it might be necessary to realign cavity filter:
Set signal to 500MHz -27dBm to input, center frequency to 500MHz, Scanwidth to 0.5MHz, turn all three M3 screws
to max. amplitude. In case curve is not uniform, coils L1, L2, and L3 can be adjusted to maximum uniformity (fig. 22)
by slightly bending them.
In case signal in frequency range is shacky, 2nd local oscillator might not be snapped in correctly. The correct snap-
in of the PLL is visible via the lock detect LED (D2), which has to be lit constantly without flickering if PLL is snapped-
in correctly.
The oscillator signal has to be fixed (crystal dependent) at 1.32GHz, it may not drift.
The PLL is snapped-in when the tuning voltage VT (measure at PAD1) is between 0.5 and 4.5V. The alignment will
bring the tuning voltage to the center of the tuning range. VT of the 2nd LO has to be between 2V and 2.5V. Constantly
check tuning voltage while aligning tuner.
Alignment is necessary in two cases: VT<2.0V and VT>2.5V.
• Case 1 VT<2.0V
Correction:
a ) Solder all adjustment areas to connect trace from C1 to C2.
b ) Remove excess solder at center conductor of resonator pad.
• Case 2 VT>2.5V
Correction:
a ) Adjustment areas may not be soldered to connect trace from C1 to C2.
b ) Add solder to resonator pad.
C Alignment of IF-Unit
Measurement setup: Apply two different signals to the input of the HM5011 via BNC T-connector and 10dB
attenuators.
Adjust HM5010/5011: Center frequency to 500MHz; all attenuators on (–40 dB)
400kHz; video filter off; scanwidth 0.5MHz/div.; marker off.
Adjust Tracking Generator: Attenuator –20dB; level max. (HM5011 only)
RF-generator: frequency 500MHz; level –5dBm
The output voltage of the tracking generator is visible on the screen by an overlay of the fixed frequency. A "zero" point
is visible within the signal to the right or to the left of the 500MHz spectral line (fig. 23
IF Filter Curve at 400kHz Bandwidth
align:
Step 1 Align (with plastic screw driver) Coil L1 (PIC 5) to maximum output amplitude and symmetry
to Y-axis.
align: Step 2 Align (with plastic screw driver) Coils 3 + 4 + 13 + 14 (PIC 5) to symmetrie to Y-axis. The "zero"
point must be at the maximum (at 500MHz) (fig.
align: Stept 3 If necessary, repeat step 1 and 2.
VR 3
L 10
L 13
L 11
L 14
L 12
VR 4
Subject to change without notice
VR 1
L 7
L 3
L 1
L 8
L 4
L 9
VR 2
fig. 23 fig. 23) (5011 only). fig. 23 fig. 23
fig. fig. 23). fig. fig.
PIC 5
IF-Amp
Board
fig. 22 for HM5010
Bandwidth
fig. 23 for HM5011
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