User's Manual

Page 8
SVR-250 Service Manual
Blue
Installation
Before installing the SVR-250, ensure that the RF and repeater sections are properly aligned per the tuning
instructions on pages 10-15 of this manual. Additionally, ensure that the SVR-250 jumpers are properly
configured for use with the particular mobile radio that it will be connected to:
J1 Controls the maximum drive level of the transmit audio output to the mobile radio. If J1 is installed, output
amp U1A will have an adjustment range of 0-100 mVPP. If J1 is removed, U1A can be adjusted between 0-
5VPP.
J2 Controls the output impedance of the transmit audio line to the mobile radio. If connected to a low impedance
point in the mobile, installing JP2 sets the output impedance to 600 ohms. If JP2 is open, the output impedance
is 2.2Kohms. Install the jumper for radios that require a lot of modulation drive or that have low impedance
microphone circuits. Remove the jumper if the SVR-250 installation decreases local microphone audio at the
mobile.
J4 Used to internally tie the local mic input of the SVR-250 to the transmit audio output line which is usually
connected to the mic hi line in the mobile.
J5 Used to internally tie the on-air detect input of the SVR-250 to the PTT output. Do so only on conventional
radios; trunking radios must have the on-air detect line connected to a line indicating that the radio is
transmitting.
J6 Changes the maximum gain of the local mic input amp from unity (Out) to 10x (In).
J7 Changes the maximum gain of the receive audio line input from unity (Out) to 7x (In).
J8 Adds a pull up (+ position) or pull down (- position) resistor to the remote enable line (blue).
J9 Adds a pull up resistor (10K to 5VDC) to mobile COR line (violet)
J10 Connects the front panel on-off control to the remote enable line to enable the SVR-250 from the front panel.
J11 Adds (Out) or removes (In) a 100KOhm resistor in series with the Tx audio line for applications with low level
mic audio and alternator whine problems (see Service Bulletin 113).
J13 Selects the Emergency output polarity: NO=pull to ground during Emg NC=break ground during Emg.
Make the connections between the mobile radio and the SVR-250 cable as follows:
Pin 1: Ground. Connect to the radio's chassis or ground plane.
Pin 2: Mobile transmit audio. Connect to the mobile transmit audio path or tone input. If connected before
pre-emphasis, ensure that the SVR-250 is programmed for de-emphasis (common data). If connected
after pre-emphasis, ensure that the SVR-250 transmit audio path is programmed as flat. Pin 2 is AC
coupled and has an output impedance of 600 or 2.2Kohms (determined by J2). RV3 sets the transmit
audio output level and J1 sets the adjustment range between 0-5VPP (J1 open) or 0-100mVPP (J1
shorted).
Pin 3: Remote enable/disable. Connect to the radio's auxiliary output or a separate switch to remotely
enable or disable the repeater. If this line goes high to activate the repeater, ensure that JP1 is set to
the “+” position. If this line goes to ground, set JP1 to the “-” position. J8 has two positions to add
a pull up (+) or pull down (-) resistor to this line if used with an open collector or dry contact output.
J10 connects this line to the front panel on/off control.
Black/Shield
White