User Manual

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DANIELS
ELECTRONICS
UT-4R400 UHF Project 25 Digital Transmitter Instruction Manual 2-5
OUT IN IN OUT 2.25 sec
OUT IN OUT IN 2.5 sec
OUT IN OUT OUT 2.75 sec
OUT OUT IN IN 3 sec
OUT OUT IN OUT 3.25 sec
OUT OUT OUT IN 3.5 sec
OUT OUT OUT OUT 3.75 sec
2.10 Kerchunk noise selection
In addition to the selectable hang timer, it is possible to add a burst of noise to the end of each
transmission, after the hang time has expired. When the transmitter is used in a repeater
configuration in digital repeat mode, it may be difficult for a mobile radio user to hear that he has
successfully “hit” the repeater, since P25 radios usually operate in a “silent squelch” mode. The
kerchunk noise is an audible indicator that the repeater was indeed keyed. Remove JU47 to enable
the kerchunk noise.
Note that the kerchunk noise is applied only when the radio is keyed by the ANALOG_COR* or
DIGITAL_COR* inputs, not from the front panel Mic connector or the PTT signal from the M-3
subrack. In addition, if the radio is keyed again before the hang time has expired, the kerchunk
noise will not be sent until the hang timer is set again by removal of the keying source.
2.11 Test Points
Test Point Signal Monitored Typical voltage
TP1 +8.0VDC regulated +8.0 VDC
TP2 Summed PTT inputs +5 VDC inactive, <0.2VDC active
TP3 Summing junction for audio signals +4 VDC, 0 VAC
TP4 Output of audio summing amplifier +4 VDC, 100 mVAC
TP5 mid-supply bias voltage for audio circuits +4 VDC
TP6
Digital Signal Processor board output to
enable RF amplifier
0 VDC inactive, +4.5 VDC active