b. Check 
U305
 pin 3 for approximately 
+12
 Vdc (Option 103 only).
c. Check for a 10 MHz sine wave greater than or equal to 1 V p-p at J305 (standard
HP 
85623),
 or at 
U302
 pin 3 with an oscilloscope (Option 103).
10. If the signal at 
U304
 pin 13 is correct (see Figure 12-7), but there is a problem with the
signals at A15J301,  A155302, A155303, or A15J304,  suspect 
U303
 or 
U304
 in the 10 MHz
Distribution circuitry.
hp running
-250,000 ns-250,000 ns
o,ooooo
 s
o,ooooo
 s
50.0 
ns/div
50.0 
ns/div
250.000 ns250.000 ns
200
set: 0
000 
:
mV/div
000 v
'1 dc
1
 f-40.00 
mV
Figure 12-6. 10 MHz Reference at 
A15J302
RF Section 12-21