Pulsar TCF-10B, System Manual, Page: 139 / 249

13.2 RF Interface Circuit
Description
This module receives RF input from the 10W PA
Module at pins A16/C16 and A18/C18, and feeds
the power through a balanced low-pass filter with
a 550 kHz cutoff (L3, L4, L1, L2 and associated
components). RF is fed through transformer T1,
for matching 50 ohm (JU4), 75 ohm (JU3), or
100 ohm (JU2) resistance to the RF line output
(45 Vrms maximum) at pins 12A/12C and
10A/10C, which provide the two-wire UHF (J1)
connection on the Rear Panel.
Four-Wire Receiver input is provided at pins 24
A/C and 22 A/C via the 4-wire BNC (J2)
connector on the Rear Panel. Jumpers JU1 and
JU5 simultaneously connect the four-wire
Receiver input to RF line output:
• IN settings for 2-wire operation
• OUT settings for 4-wire operation
Isolation transformer T2, together with series
resistor R1, forms an attenuator with 13 dB loss.
Receiver input (at pins 28 A/C) is adjusted by
jumper JU6:
• When in the NORM position, Receiver
maximum input is 70 Vrms at 5,000 ohms
• When in the HIGH position, JU6 overrides
the attenuator, providing lower input
impedance (Receiver maximum input is 17
Vrms at 1,000 ohms).
13.3 RF Interface
Troubleshooting
With the PC Board plugged into the chassis, you
can monitor the voltage output to the RF line at
TJ1 and TJ2. You can monitor receiver input at
TJ3 and TJ4.
Should a fault occur in the RF Interface Module,
you can remove the PC board and check the
components by conventional means.
13.3.1 Capacitors
Remove from the circuit with jumpers JU2, JU3
and JU4 and check for shorts, dissipation factor,
and capacitance. (Perform checks using a signal of
10 kHz or higher.)
13.3.2 Inductors
Check with an ohmmeter.
13.3.3 Transformers
Check for open circuits.
Page 13–2 April 1997
TCF–10B System Manual
Technologies, Inc.