5-16.
LEVELED RF OUTPUT ADJUSTMENTS
(Cont’d)
35. On the OUT, press [SHIFT] [PWRSWP] [0] [dBm]to set the ALC level at
0
dBm and then press
[START FREQI [1] [4] [GHz]. Slowly rotate the OUT’s RPG clockwise while watching the
oscilloscope display for squegging. If any squegging is seen, stop at the start frequency at which
it occurs. If the squegging occurs in Band 3
(13.5 to
20 GHz), adjust A24R8 (X3C) counter-
clockwise until the squegging is gone. If the squegging occurs in Band 4 (20 to 26.5 GHz), adjust
A24R11 (X4C) counter-clockwise until the squegging is gone.
36. Repeat step 35 for ALC levels of —5 dBm, —10 dBm and —15 dBin.
NOTE
If adjustments of the Cal Constants were made in this procedure, the Cal
Constants data stored in the “working memory” should be copied into
the “protected memory” by pressing [SHIFT][MHz] [1] [4] [Hz] [SHIFT]
[kHz] [5] [3] [4] [9] [Hz]. Wait for “CALIBRATION RESTORED” to be
displayed in the ENTRY DISPLAY, then press [INSTRPRESET].
LEVELED SQUEGGING TEST USING A SPECTRUM ANALYZER
Description
The OUT’s RF output signal is down converted using a Local Oscillator (LO) and a mixer. The IF output
of the mixer is fed to a spectrum analyzer. Any squegging of the OUT will appear as a spurious
response on the IF signal.
This test should be performed after SYTM tracking and delay, and SRD unleveled bias adjustments.
Equipment
Synthesized Sweeper
HP 8340B Option 001
10 dB Attenuator
HP 8493C Option 010
Mixer
HP P/N 0955-0307
Spectrum Analyzer
HP 8566B
Adapters:
APC 3.5
(f) To Type N
(in)
HP P/N 1250-1744
(required
if
OUT
is an
HP 8341 B)
APC 3.5 (f) to APC 3.5
(f)
HP P/N 5061 -5311
(required if OUT is an HP 8340B)
37. Connect equipment as shown in Figure 5-59. Connect the mixer LO input port directly to the LO
RF
output
connector to obtain maximum mixer LO input level. Allow at least 30 minutes warm up
time.
38. Press the LO [INSTRPRESET]. Press [STARTFREQ] and enter [6]
[.]
[4] [GHz]. Press [STOP
FREQ] and enter [1] [2]
[.]
[9] [GHz]. Press [POWERLEVEL] and enter [1] [0] [dBm].
Press
[SHIFT][CF] and enter [1] [0] [0] [MHz] for a step size of 100 MHz. Press [MANUAL]
SWEEP
and
enter [6]
[.]
[4] [GHz] to set the LO to CW at 6.4 GHz.
39. On the OUT, press [INSTRPRESET]. Press [STARTFREQ] and enter [7] [GHz]. Press [STOP
FREQI and enter [1] [3]
[.]]
[5] [GHz].Press [POWERLEVEL] and using the front panel rotary
knob, adjust for maximum leveled power (just before the UNLEVELED light comes on). Press
[SHIFT][CF] and enter [1] [0] [0] [MHz] for
a step size of 100
MHz. Press [MANUAL]SWEEP and
enter
[7] [0Hz]. The mixer IF frequency is now 600 MHz.
HP 8340B/41B
Adjustments
5-111