Operating instructions

RF Technology T350/T500 Page 23
7 SPECIFICATIONS 7.4.18 External ALC Input
7.4.17 External Tone Input
Compatible with R500 tone output
7.4.18 External ALC Input
Output will be reduced 20dB by pulling the input down to below 1V. (Typically more
than 40dB attenuation is available.) The input impedance is ≅10kΩ, internally pulled
up to rail.
The external ALC input can be connected to the power control circuit in Eclipse
external power amplifiers.
7.4.19 T/R Relay Driver
An open collector transistor output is provided to operate an antenna change over relay
or solid state switch. The transistor can sink up to 250mA.
7.4.20 Channel Select Input / Output
Coding - 8 lines, BCD coded 00 - 99
Logic Input Levels - Low for <1.5V, High for >3.5V
Internal 10K pull down resistors select channel 00 when all inputs are O/C.
7.4.21 DC Remote Keying
An opto-coupler input is provided to enable dc loop keying over balanced lines or local
connections. The circuit can be connected to operate through the 600Ω line or through
a separate isolated pair.
7.4.22 Programmable No-Tone Period
A No-Tone period can be appended to the end of each transmission to aid in eliminating
squelch tail noise which may be heard in mobiles with slow turn off decoders. The No-
Tone period can be set from 0--5 seconds in 0.1 second increments. The No Tone
period operates in addition to the reverse phase burst at the end of each transmission.
3
7.4.23 Firmware Timers
The controller firmware includes some programmable timer functions.
Repeater Hang Time - A short delay or ``Hang Time'' can be programmed to be added
to the end of transmissions. This is usually used in talk through repeater applications to
prevent the repeater from dropping out between mobile transmissions. The Hang Time
can be individually set on each channel for 0 - 15 seconds.
Time Out Timer - A time-out or transmission time limit can be programmed to
automatically turn the transmitter off. The time limit can be set from 0-254 minutes