Elmo DBP SERIES HF Filter R195, R196, C61, C62, 15Kohm R195=R196 30Kohm, 160x103, C61 = C62 =

90

HF Filter (R195, R196, C61, C62)

The function of the HF filter is to reduce the amount of noise present on the signal inputs to the 2S82, reaching the Phase Sensitive Detector and affecting the outputs. Values should be chosen so that

15Kohm < R195=R196 < 30Kohm

160x103
C61 = C62 = ------------	(pF)
R195 x fr

fr = Reference frequency in KHz R195 in Kohm

This filter gives an attenuation of 3 times at the input to the phase sensitive detector.

AC Coupling of Reference Input (C60)

Select C60 so that there is no significant phase shift at the reference frequency. That is,

106			100 x R192
C60 = --------------	(pF)	Rx =	------------ (Kohm)
fr(KHz) x Rx			100 + R192
R192 in Kohm

If Rx yields less than 50K, install a value of Rx=50K in the C60 equation.

Maximum Tracking Rate (R201)

The VCO input resistor R201 sets the maximum tracking rate of the converter and hence the velocity scaling as at the maximum tracking rate, the velocity output will be 8V.

Decide on your required maximum tracking rate, "T" , in revolutions per second. Note that "T" must not exceed the specified maximum tracking rate or 1/16 of the reference frequency.

DBP - Rev 6/93