User Manual

TR-800 Service Manual
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low state at the input of the NAND gate U0107A, one quarter of a MC14011B, will be conversed to a high
state to drive the buffer for the Rx Carrier signal. The active low level of Rx Carrier signal, along with the
OPT enable signal, cause a series of NAND gates, U0103D, U0103C and U0103B to generate a high dc
level to turn on Q0102. The output of Q0102 is pulled low for pin8 of “J0104-Slave” and keys the
transmitter of slave radio. The green “Rx” LED, CR0105, illuminates.
Q0111 is used to prevent the simultaneous active state on PTT and Rx Carrier signal of “J0102-Main”,
which possibly causes unwanted tie condition of keying of both radios.
Accessory D-SUB 15pin receptacle (“J0103-Acc”)
The accessory D-Sub, “J0103-ACC”, is connected to “J0102-Main” and “J0104-Slave” to supply Rx
audio and PTT for linked radios (repeaters) or external controllers. Receive audio and PTT activation
from the linked facilities are applied to the repeater for transmission.
Display Unit (U0110, PB01-PB06, K02, Q0113 and Q0118)
All the functional triggers of enable and disable come from keypad PB01 to PB06. K02 is an encoder
switch for front speaker audio output adjustment. A high output from pin37 of CPU U0110 will turn Q0119
on, driving the base of Q0118 to go low. The backlight LED for the keypad, CR0107, CR0108,
CR0111-CR0114 illuminate. Another backlight driver, Q0113, is controlled by Q0114 through the output
from pin17 of U0110.
Peripheral Circuitry (U0108, U0109, KR00 and KR03)
Operating power bus for all the electronics originates from the switch power 13.8Vdc output, pin9 of
“J0107-Slave”, and goes through U0109 and U0108 to obtain the reference voltages of 9Vdc and 5Vdc.
KR00 is a DPDT relay driven by transistor Q0123. The output from pin25 of U0110 will turn on/off Q0123,
which activates relay KR00 to toggle the front speaker audio routes from slave radio or from main radio.
KR03 is another SPDT relay for audio test requirement. A dc level high output from pin26 of U0110 will
turn on Q0124 and keys relay KR03. The receive audio to the speaker is blocked and routes only to pin8
of the front RJ45 connector J0109.
IMPORTANT NOTE
Using CTCSS or CDCSS tones may have a lower
probability to open squelch than carrier operation. But the
CTCSS codes near 100Hz and 150Hz have a high false
opening probability due to 50Hz AC power harmonics.
Countries having 60Hz AC power may have false opening
on 120Hz and 180Hz. CTCSS code 254.1Hz has a high
probability of squelch tails.