TN500 SR-39-1 Subrack
MT-3/4 Radio Systems
TECHNICAL NOTES
Page 3 of 4
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Power Input
The main power input (+10 to +17 Vdc; +13.8 Vdc nominal) connector is located at the back of the subrack, on
the motherboard. There is an identical +9.5 Vdc power output connector on the motherboard that is used to
power other Codan equipment at +9.5 Vdc (the CI-RC-4M-G2 controller, for example).
NOTE: Do not connect the main power input to the +9.5 Vdc power output connector, as a transient suppressor
(over voltage protection) will short to ground to protect the equipment.
Reverse voltage protection and over voltage protection (transient suppressor) is provided at the main power input
as well as the +9.5 Vdc line. The main power input is protected with a standard fast-blow 15 amp fuse. These
components may require replacing if the power supply is not connected properly, or even after a power surge or
a lightning strike. The two transient suppressors have diff erent voltage ratings for the main power input and +9.5
Vdc lines. Figure 5 shows the subrack / motherboard rear view.
Antenna Relay Activation
The motherboard on the subrack contains a set of jumpers that are used to activate the optional antenna relays in
the System Regulator module from the Transmitter PTT IN and PTT OUT signal lines.
JU36 TXA PTT OUT activates Relay A JU37 TXA PTT IN activates Relay A
JU39 TXA PTT OUT activates Relay B JU40 TXA PTT IN activates Relay B
JU42 TXB PTT OUT activates Relay A JU43 TXB PTT IN activates Relay A
JU45 TXB PTT OUT activates Relay B JU46 TXB PTT IN activates Relay B
Simplex Operation
The motherboard on the subrack contains a set of jumpers that are enabled when the radio system is operated in
simplex mode (simplex base station or simplex links). The jumper connects the Transmitter PTT OUT signal line
to the RX MUTE. This jumper will cause the receiver to mute when the transmitter is keyed.
JU38 TXA PTT OUT mutes RXA JU41 TXA PTT OUT mutes RXB
JU44 TXB PTT OUT mutes RXA JU47 TXB PTT OUT mutes RXB
DB25 Connector to DSP-223 and IP-223 / IP-224
Connector J10 is a female DB25 connector which can be used for basic base connections. When connected to a
Telex DSP-223 or IP-223 / IP-224, a standard straight-through male-to-male DB25 cable can be used with some
motherboard jumper changes. The IP-224 requires a female DB25 to male DB37 adapter. The IP-223 / IP-224
also requires that 2 pins on the DB25 (PTT COM - pin2 and MON COM - pin 16) are wired to ground for proper
operation. The DB25 can also be jumpered for Balanced Audio direct to / from the receiver / transmitter or Auxiliary
Audio (recommended) through the controller.
WARNING: JU108 must be confi gured correctly for DSP-223 or IP-223 / IP-224 or damage can occur.
JU104 A = RX A Bal O/P2 or B = AUX 1 AUD O/P2 JU107 A = RX A Bal O/P1 or B = AUX AUD O/P1
JU105 A = TX A Bal I/P2 or B = AUX 1 AUD I/P2 JU108 A = DSP-223 / +13.8 V or B = IP-223 & IP-224 / RX A COR
JU106 A = TX A Bal I/P1 or B = AUX 1 AUD I/P1 JU109 TX A SEC / CLR I/P (installed to enable TX A SEC / CLR I/P)
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