DE
DANIELS
ELECTRONICS
2-4
VT-4R150 VHF Project 25 Digital Transmitter Instruction Manual
JU24
Out
Connects fr pnl MIC MODE switch directly to Digital Signal Processor board
JU25
Out
Connects summed PTT signals directly to Digital Signal Processor board
JU26
In
Connects channel select line CSEL3 to Digital Signal Processor board
JU27
Out
Connects Digital Signal Processor board to green front panel LED
JU28
Out
Grounds Digital Signal Processor board bank select input
JU29
Out
Connects Bank Select input to directly to the Digital Signal Processor board
JU30
In
Connects channel select line CSEL0 to Digital Signal Processor board
JU31
In
Connects channel select line CSEL1 to Digital Signal Processor board
JU32
In
Connects channel select line CSEL2 to Digital Signal Processor board
JU33
A
Connects 68HC11 uP to yellow front panel LED
JU34
In
Enables yellow front panel LED
JU35
In
Enables green front panel LED
JU36
In
Enables yellow front panel LED
JU37
In
Connects TX PTT OUT* signal to subrack
JU38
Out
Allows bootstrap programming of 68HC11 uP
JU39
Out
Allows programming of EPROM version of 68HC11 uP
JU40
Out
Provides serial communications for bootstrap programming
JU41
In
Allows 68HC11 uP to control green front panel LED
JU42
In
Allows 68HC11 uP to control yellow front panel LED
JU43
In
Bit 3 (MSB) of hang time select
JU44
In
Bit 2 of hang time select
JU45
In
Bit 1 of hang time select
JU46
In
Bit 0 (LSB) of hang time select
JU47
Out
Disables “kerchunk” noise at the end of a transmission
JU48
Out
No function
JU49
Out
No function
JU50
Out
No function
2.9
Hang Timer Selection
Hang time is a selectable time delay, which can be enabled to keep the transmitter keyed after its
PTT input is released. It can be used to keep a RF channel open in low signal conditions when the
receiver might be squelching intermittently. It is also commonly used by repeater users in order to
keep the transmitter keyed long enough to key their mobile radios briefly at the end of their
transmission in order to be sure that they’ve hit the repeater. The duration of the hang timer is
selectable in 250 ms. increments from 0 (disabled) to 3.75 sec by changing the states of jumpers
JU43-46. A table of the hang timer durations is shown below. Note that the Hang Time 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.
JU46
JU45
JU44
JU43
Hang Time
IN
IN
IN
IN
0 (disabled)
IN
IN
IN
OUT
250 ms
IN
IN
OUT
IN
500 ms
IN
IN
OUT
OUT
750 ms
IN
OUT
IN
IN
1 sec
IN
OUT
IN
OUT
1.25 sec
IN
OUT
OUT
IN
1.5 sec
IN
OUT
OUT
OUT
1.75 sec
OUT
IN
IN
IN
2 sec