Ericsson 19D902783G1, Maintenance Manual, Page: 9 / 92

PARTS LIST & PRODUCTION CHANGES
PRODUCTION CHANGES
Changes in the equipment to improve performance or to simplify circuits are
identified by a "Revision Letter" which is stamped after the model number of the
unit. The revision stamped on the unit includes all previous revisions. Refer to
the Parts List for the descriptions of parts affected by these revisions.
Rev. A - 19D902494G1, 25 kHz IF Module Board
To improve performance in high temperature environments and to
eliminate Audio Level drifting, changed voltage regulator U8 and vari-
able resistor VR1.
U8 was: 19A704971P11, 8 Vdc; sim to MC78L08ACD.
VR1 was: 19A705496P5 20K ohms 0.1w; sim to Murata RGV4E203.
Rev. B - 19D902494G1, 25 kHz IF Module Board
To change Squelch Driver operation to allow compatibility with GETC,
changed resistors R56, R57, and R69.
R56 was: 19B800607P182 Metal film: 1.8K ohms
±
5%, 1/8 w.
R57 was: 19B800607P822 Metal film: 8.2K ohms
±
5%, 1/8 w.
R69 was: 19B800607P102 Metal film: 1K ohms
±
5%, 1/8 w.
SYMBOL PART NO. DESCRIPTION
- - - - - - - - - - -CRYSTALS - - - - - - - - -
Y1 19A149974G7 Filter, crystal: Fc = 21.4 MHz, 3 dB BW =
15.0 kHz. Insertion loss = 2.0 dB max.
Y2 19A149974G8 Filter, crystal: Fc = 21.4 MHz, 3 dB BW =
15.0 kHz. Insertion loss = 3.0 dB max.
Y3 19A702284G5 Quartz crystal unit: 20.945000 MHz
±
10 ppm
@ 25
°
C.
Y4 19A149976P1 Fixed: 455 kHz.
LBI-38643C
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