The second and third numbers are the M and N divide numbers respectively. The waveform at test points 3 and 7, 5 and 6, and 1 and 2 should be as shown in Figures 1, 2, and 3 respectively. The Center Frequencies for Figure la, lb, lc, and Id are 3.77 GHz, 3.96 GHz, 4.15 GHz, and 4.34 GHz respectively. The M and N numbers are 20, 21, 22, and 23 respectively.

Oscilloscope control settings for Figure 1, Figure 2, and Figure 3 are:

Vertical: 0.1 V/Div

Horizontal: 0.2 psec/Div

Probe: 1O:l

Note

Waveforms on the M Divider 0 require the M/N VCO be phase-locked at 380

 

MHz. If the M/N VCO is not phase-locked, an external signal generator may

!iil

be used to locate the failure.

 

 

 

Note

All waveform voltage levels are emitter coupled logic (ECL) levels:

 

-0.9 V = high, -1.7 V = low.

3

 

 

 

Mixer (EJ and IF Amplifier @

The Mixer inputs are 400 MHz from A7A2 100 MHz VCXO and 355 to 395 MHz from A7A4 M/N Output. When the M and N numbers are the same, the M/N output frequency is

380MHz.

A7A3 3