Midian TT-9 User Manual

TT-9

DTMF Dialing Encoder

Manual Revision: 2011-07-15

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SPECIFICATIONS

Operating Voltage 5.5-15 VDC
Operating Current 3 mA
PTT Output Current 250 mA
Audio Output Level 0-750 mV(rms)
Audio Output Impedance 1 K or 50 K
Twist 0-3 dB
Max Tone Distortion 2%
Interkey Time (Auto PTT) 2 seconds
Adjustment Pots 1 Turn
Operating Temperature -30° to +60°C
Dimensions with Bezel Frame (standard) 2.4" x 1.9" x 0.4"
Dimensions without Bezel Frame 2.0” x 1.5" x 0.25"

GENERAL INFORMATION

The TT-9 is a 12-digit DTMF dial encoder with snap-dome keypad in a mountable bezel frame. The TT-9 will
automatically assert the PTT output when a button is pressed and hold the PTT output for 2 seconds for
subsequent digits to follow. The DTMF tones are generated out the TX Audio Output for as long as the key is
pressed.

The following diagram shows the DTMF tone pairs generated when a particular digit is pressed. For example
when the 1 digit is pressed the TT-9 will generate 697 Hz and 1209 Hz simultaneously.

1 2 3

697 Hz

4 5 6

7 8 9

* 0 #

1209

Hz

1336

Hz

770 Hz

852 Hz

941 Hz

1477

Hz

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HARDWARE INSTALLATION

Be certain to follow standard anti-static procedures when handling any of Midian’s products.

Connector P1
P1-1 – Green – TX Audio Output – Connect to a high impedance audio point in the transmitter modulator.
P1-2 – Red – 5.5 - 15 VDC – Connect to switched battery point in the radio.
P1-4 – Black – Ground – Connect to the nearest ground plane in the radio.
P1-5 – Blue – Speaker Output– Connect to the high side of the radio's speaker. The speaker completes the

ground for the emitter follower Q3. CAUTION: When attaching this lead to a 4 or 8 Ohm speaker, add a 100
Ohm resistor in series with this blue lead to limit current. When using 20-40 Ohm speakers, the onboard resistor
in series with Q3 should be sufficient.

P1-9 – White – PTT Output – Connect to the PTT switch of the radio. The PTT Output gives an open-collector to
ground when activated and is rated at 100 mA continuous.

The remaining 8 wires are not connected.

HARDWARE ALIGNMENT

DTMF Output Level: The DTMF output level can be adjusted for 0-750 mV RMS by adjusting R22. In a wide

band system, set R22 to 3.3 KHz (66% of 5 KHz) of deviation per EIA specifications. In a narrow band system,
set the R22 to 1.65 KHz (66% of 2.5 KHz) of deviation per EIA specifications.

R-22

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