Garmin GTN 625 Installation Manual page 17

GTN 625/635/650 HARDWARE MOD LEVEL HISTORY
The following table identifies hardware modification (Mod) Levels for the GTN 625, GTN 635 and 
GTN 650. Mod Levels are listed with the associated service bulletin number, service bulletin date, and the
purpose of the modification. The table is current at the time of publication of this manual (see date on front
cover) and is subject to change without notice. Authorized Garmin Sales and Service Centers are
encouraged to access the most up-to-date bulletin and advisory information on the Garmin Dealer
Resource web site at www.garmin.com using their Garmin-provided user name and password.
SERVICE
MOD
BULLETIN
LEVEL
NUMBER
1 SB 1203
2 N/A
3 N/A
190-01004-02
Rev. F
SERVICE
BULLETIN
DATE
Some GTN 650 and GTN 750 units require upgrade or
March 8,
MOD 1 marking of previous upgrade to improve the reli-
2012
ability of the VHF navigation receiver.
In installations with insufficient antenna isolation, some
GTN 635/650 and GTN 750 units require upgrade to
N/A MOD 2 to prevent squelch from breaking when the COM
receiver is overloaded, or to keep the transmitting COM
from causing the GTN's VOR receiver from flagging.
Modification for installations that need to meet RTCA/
N/A DO-160F, Section 8, Category U, Curve G vibration (typi-
cally helicopter).
PURPOSE OF MODIFICATION
GTN 625/635/650 TSO Installation Manual
Page xi