Frequency Counter - Motorola R-2001A Service Manual

4-10. FREQUENCY COUNTER. The frequency Counter measures inputs in a range from 10 Hz to 35 MHz.
The in put to the frequency counter is through theVert/Sinad/DVM/Counterin, BNC connector (located in the
OSCILLOSCOPE section of the front panel). The counter sensitivity is controlled by the scope Vert switch.
The following shows the minimum sensitivity for each switch setting:
The autorange output of the counter is displayed on the CRT to a resolution of 0.1 Hz or 5 digits.
Do not connect transmitter directly to the frequency counter input. Instead use the
RF In/Out connector and the frequency error meter for transmitter frequency
measurements.
4-11. SPECTRUM ANALYZER. Input to the spectrum analyzer is through the RF In/Out connector. Select
the spectrum analyzer position on the DISPLAY column. Place the FUNCTION switch in the monitor position.
Select the desired width of sweep by the Dispr/Sweep control. The center frequency is selected from the
memory or entered directly from the keyboard, it is displayed at the top-right of the CRT. The following is an
example of locating the frequency of an incoming signal with the spectrum analyzer.
a. Connect antenna to RF IN/OUT connector.
b. Set FUNCTION switch to Mon. and DISPLAY to Sped. Analyzer.
c. Select center frequency from memory table or enter directly from keyboard.
d. Adjust Disp/Sweep control for desired spectrum span.
e. Adjust Step attenuator \f required to reduce sensitivity.
f. To determine whether a given displayed signal is valid or being internally generated, flip the
Image/Dplx switch to the opposite position. If signal moves in frequency or disappears, it
then/represents an internally generated spurious response or received image.
g. Use the RF Scan control to move desired signal to center of the screen. If the signal is located to the
right of screen center line, move the RF Scan control clockwise into one of five positive stepping
modes. If the signal is to the left of screen center line, turn the RF Scan control counter clockwise to
one of five negative stepping modes.
h. Adjust Dispr/sweep.control fully counterclockwise for 1 MHz spectrum span.
i. Again use RF Scan to recenter signal on screen.
j. Set DISPLAY to Qen/Mon Mtr.
k. Now adjust the RF scan control to minimize any existing frequency error between the incoming signal
and the Monitor frequency.
Switch setting
———————
0.01
0.1
1.0
10.0
NOTE
4-15
Sensitivity
—————
50 mV RMS
500 mV RMS
5V RMS
50V RMS