Hameg Instruments HM5011 Serviceanleitung Seite 28

6. Control of fixed LO-Level
6.1 To check 2nd LO-level, cap C20 (22pF) has to be removed and 50Ohm Coax-cable has to be connected to -
13dB attenuator of output. Connect other end of coax cable with adequate test analyzer.
6.2 Adjust test analyzer to 1.35 GHz center frequency; the LO-level to be measured has to be -17dBm (±1 dB)
(consider attenuation of cable).
6.3 If cap is not removed and coax cable is connected parallel to mixer to the VCO-branch, a level of approx. -24
dBm (±1dB) should be measured due to decreased load resistance.
7. Check of VCO
7.1 Adjust HM5011 to Zero Scan, center frequency to 500MHz.
7.2 Remove Cap C14 (22pF), connect one side to attenuator output, other side stand up in the air.
7.3 Connect Cap side sticking up in the air to center conductor of 50 Ohm cable. Solder shielding of cable directly
next to Cap to ground. Connect other end of Cap to Analyzer input (i.e. Advantest R3361A). Start 1.35GHz -
Stop 2.35GHz reference level: 0dBm.
7.4 VCO signal which can be observed on the test analyzer has to shift according to center frequency (tuning
voltage). Tuning range has to be at least from 1350 to 2350 Mhz. continuously and without interruption. It
should not go under absolute level of +7dBm (coax cable of 1 mtr. has 1-2 dB of attenuation at 2GHz). Level
has to be between +7 dBm and +10 dBm.
7.5 Connect coax cable parallel to 1st mixer to VCO-branch. A level of +5 dBm to +8 dBm due to decreased load
resistance over frequency band.
8. Check of Attenuators:
8.1 Set -30dB attenuation to Tuner and to 0dB attenuation to TG.
8.2 Set Center Frequency to 500MHz, 100MHz/Div. span.
8.3 Connect tracking generator to tuner input.
8.4 TG-line has to be visible.
8.5 Switch on additional attenuators. Attenuation for each attenuator switch has to be 10dB (±1 dB)
9. TG Level Adjustment:
9.1 Connect TG to reference analyzer.
9.2 Set HM5011 to Zero Scan and 500MHz Center Frequency.
9.3 Release all attenuator buttons of TG (0-dBm) and turn TG-level to maximum.
9.4 Adjust amplitude to +1dBm with Pot RV4 on TG.
9.5 turn TG-level to minimum.
9.6 Adjust amplitude to -10dBm with Pot RV3 on TG.
9.7 Amplitude has to be adjustable now between +1dB and -10dB.
10. Final Check
10.1 Position of TG-level has to align in both bandwidths (400kHz and 20kHz). If necessary, align with IF-Amp.
10.2 TG-level knob has to be adjustable from +1 to -10dBm.
Subject to change without notice 27