[R-390] Crystal check

[jkharvie]

Making progress with servicing my EAC receiver and I thought it might be of some value to know how the crystals in the deck have aged regarding frequency and amplitude performance.

I am not aware of any specific language regarding how far out of spec the crystals can be and the receiver still operating well but this is what I found.

Using a scope and digital signal generator I conducted an evaluation of each crystal with a quick assessment

Results as follows
Procedure for Crystal frequency performance assessment
Tools needed
Digital Signal Generator (0-60Mhz, 2 channel, multi waveform, 0.01 Hz resolution)        
Oscilloscope - Tektronix TAS 475 (100 MHz- 4 Channel)        

Procedure:        
1) With care remove crystals from receiver, note placement position and orientation. Label each crystal for convenience
2) Set signal generator to 0.4 volts, waveform to sine wave        
3) Hook scope up to crystal in series with signal generator        
4) Adjust scope for best waveform presentation
5) At the precise frequency of resonance, the measured signal amplitude will increase, thus adjust signal generator frequency for highest crystal resonance peak        
6) Record frequency of crystal when peak is measured        
7) Replace crystals into receiver
8) If error is higher than 0.00015% offset from design frequency consider replacement of that crystal9) Note the voltage, at resonance the peak should be clearly higher 


Crystal Number)Labeled Frequency(kHz)_resonancefrequency (kHz)_"delta(kHz)P"_"delta(kHz)F"
1)9000.00_9,000.78_0.78P (pass)
2)9500.00_9501.22_1.22P 
3)10000.00_10001.2_1.20P    
4)10500.00_10501.52_1.52P    
5)11000.00_11001.72_1.72P 
6)11500.00_11501.21_1.21P  
7)12000.00_12001.82_1.82P  
8)12500.00_12501.44_1.44P  
9)13000.00_13001.74_1.74P  
10)14000.00_14001.96_1.96P    
11)14500.00_14501.82_1.82P 
12.1)15000.00_15021.83_X_21.83F (fail)
12.2)15000.00_15000.07_0.07P (Replacement unit)    
13)15500.00_15502.11_2.11P
14)16000.00_16002.15_2.15P  
15)17000.00_17001.94_1.94P  

Thoughts?
AlsoHappy New Year to everybody!