Boonton 4530 Peak Power Meter Service Manual - Manual (Page 14)

BOONTON ELECTRONICS a WIRELESS TELECOM GROUP COMPANY
14
3) 50MHz Calibrator RF Alignment
Note: The calibrator alignment adjustment is sealed at the factory during initial calibration, and should not
require routine adjustment. This procedure should only be performed if a new calibrator has been
installed in the instrument or if the output or AGC tests in the previous section failed.
Warning
Extreme caution should be used when handling the 4530 with the cover removed.
High voltages are present at the Power supply. Components inside are ESD
Sensitive.
a. Turn off the 4530 and disconnect power from the instrument. Remove the instrument’s cover by
removing the 4 screws in the rear. Place the 4530 upside down on the bench and reconnect power.
Turn on the instrument and wait for it to boot up.
Do not open the calibrator. The calibrator has an adjustment hole in its cover. This hole must be
covered with copper tape during normal operation. If you do not have copper tape to replace this seal,
do not break it. Likewise, if you do not have a Murata Eire TZBX Special Trim Cap tool or equivalent
(0.047" Square Ceramic Tip) do not break this seal or attempt to adjust C16.
b. Connect a 1 Watt 50 ohm termination to the calibrator’s output connector.
c. Connect the 4530 instrument (“UUT”) to a terminal or host computer using the serial port or GPIB
interface, and verify proper communication. See 4530 Instruction Manual for details on
communication interfacing.
d. Send “SYSTEM:LANG BOON” to the UUT.
e. Send “SYSTEM:LANG BOON” to the UUT.
f. Send “$CAL:DAC 40000; $CAL:ATTEN 0” to the UUT.
g. Select Main Menu > Calibrator >IntStatus to view the calibrator’s AGC signal and record the starting
D/A count, (typically 110 to 200): Starting D-to-A count: ______________
h. Remove the copper foil seal from the adjustment hole on the calibrator’s cover.
i.
With a Murata Eire TZBX or equivalent Trim Cap tool (0.047" Square Ceramic Tip). Adjust C16
through the hole in the calibrator’s cover for the minimum A/D count on the 4530 display (IntStatus).
This adjustment is very touchy. You will notice peaks and valleys in the A/D count as the cap is
adjusted.
Since there are no stops on the trimming capacitor (C16), it can rotate continuously. This
should be avoided, as it will eventually damage the capacitor.
j.
Once a null has been found, carefully remove the tool and replace copper foil seal over the hole. If
the reading goes up significantly as the tool is removed, try making the adjustment again.
k. Record the new D/A count (typically 110 to 200):
Adjusted D-to-A count: ______________
l.
Send “$CAL:DAC 50000; $CAL:ATTEN 0” to the UUT.
m. Remove the dummy load and connect an RF powermeter to the calibrator’s output.
n. Verify that the calibrator output is between 20.5 and 21.4 dBm
o. Send “OUTPUT:INTERNAL:SIGNAL OFF” to the UUT.
p. Remove power from the 4530, and reinstall the cover.