Test Microphone Input; External Tone Input; External Alc Input; T/R Relay Driver - RF Technology T220 Operation And Maintenance Manual

7 SPECIFICATIONS

7.4.16 Test Microphone Input

200 Ω dynamic, with PTT

7.4.17 External Tone Input

Compatible with R220 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 ≅ 10k Ω , 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 600$\Omega$
line or through a separate isolated pair.
RF Technology T220 Page 21