Transmitter Model T21 Controls and Features:
Note: Taking a few minutes now to read these instructions will save time and ensure
proper system operation.
The T21 is an FM Transmitter that operates in the 72 to 76MHz business frequency band. It
can be used with a microphone as a stand-alone system, or it can be connected to an
existing sound system.
A Part 90 FCC license is required.
T21 Front Panel:
1. Power LED
- Indicates power ON.
2. “OK” Audio LED
- Flashes to indicate nominal audio input level.
3. “HI” Audio LED
- Flashes to indicate excessive audio input level.
4. Audio Adjust Control
- Adjusts audio input level.
5. Transmit “On” LED
- Indicates a valid channel has been selected and the RF carrier is on.
6. Transmit “WB” LED
- Indicates a valid wide-band channel has been selected.
7. Transmit “NB” LED
- Indicates a valid narrow-band channel has been selected.
8. Tape Output
- 1/4” TRS jack provides line-level, unbalanced audio output for tape recorders,
relay feeds, or a stereo or mono headphone for monitoring.
T21 Rear Panel:
1. Audio Input Jack
- Concentric XLR/ phone plug jack for balanced and unbalanced
Mic/Line/70V audio inputs. Provides simplex power for condenser mics.
2. Audio Inputs
- Screw terminals accept 3 unbalanced, line-level inputs. All inputs are actively
mixed.
3. Input Level Selector
- 3-way switch selects Mic/Line/70V input level for concentric jack only.
4. High-Pass Filter
- 3-way switch provides low-frequency roll-off to reduce system noise and equalize
frequency response for hard of hearing listeners.
5. Channel Selector Switches
- Two rotary switches determine the operating frequency. Selects
8 wide-band channels and 68 narrow-band channels.
6. Antenna Output
- Connector for remote antenna. The standard T21 includes a “rubber duckie”
type antenna that threads into the top of the cabinet. For installations requiring rack mounting or
remote antenna locations, the T21 has an optional coaxial antenna (ANT 005).
7. RF Power Switch
- 3-way switch determines RF output power. It is used to reduce RF hum and buzz
in amplifiers/mixers/etc. that are disturbed by RF produced by the transmitter.
8. Power Supply Connection
- Coaxial DC connector for 24VAC remote power supply.
Transmitter Set-Up and Operation:
Page 3
Tape Out/Phones
Audio Level
Hi
Ok
Power
FM Auditory AssistanceTransmitter
Adjust
Williams Sound
+
-
WB
NB
On
Transmit Status
1
2
3
4
5
6
7
8
Balanced Audio Input
Line
Mic
70V
FM Auditory AssistanceTransmitter
Select
Unbalanced
Audio Inputs
20 Hz
175 Hz
725 Hz
Hi-Pass Filter
Antenna
Power: 24 VAC, 60 Hz, 10VA
RF Power
75 Ohm
Made in USA
Williams Sound Corp.
Channel
COM
IN 1
IN 2
IN 3
-12dB
Max
-6dB
1st
Digit
2nd
Digit
Use with TFP 016 Power Supply
0
1
1
2
3
4
5
6
7
8
