V. G. ELLERBRUCH, F. C. FITCHEN AND R. W. SAWREY 
1109 
200 MHz 
100 MHz 
FiGURK 5. — Plot of a 50-ohm resistor. 
Crystals cause severe problems for the de- 
I signer because of the unit-to-unit variations in 
i resonant frequency, series resonant resistance 
and shunt capacity. Even though the manufac- 
turer gives accurate values for these 3 variables 
at the resonant frequency, the complete story 
j is not told. 
Figure 7 shows a plot of data on 2 crystals 
that were purchased from different manufac- 
turers. Curve A is a crystal that was specified 
to have a series resonant frequency of 151.125 
MHz, with a resonant impedance less than 100 
ohms and a shunt capacity less than 7 pF. 
Curve B shows the data for a crystal that was 
specified to have a series resonant frequency 
of 151.023721 MHz, series resonant resistance 
