5
HARDWARE INSTALLATION
Be certain to follow standard anti-static procedures when handling any of Midian’s products.
P1-4 – Black
– Ground – Connect to the nearest ground point.
P1-2 – Red
- +5.5 – 15 VDC – Connect to switched B+ in the radio.
P1-3 – Brown
– COR/COS – Connect to point in the squelch or CTCSS circuit that changes logic level when
carrier is received.
P1-6 – Orange
– RX Tone Input – Connect to an audio point in the receiver, usually the high side of the volume
control or discriminator output. When using CTCSS, pick up the audio after the high pass filter.
P1-7 – Yellow
– Monitor/Squelch Out – Connect to a point in the squelch circuit that normally changes logic level
with carrier. The squelch polarity is set in the programming software and by selecting the polarity of D-4 by
inserting either JU5 or JU6. R-47 can be changed to provide more or less current as needed. Do not allow the
Monitor/Squelch Output to conflict with the COR/COS lead input.
P1-10 – Gray/White
– Horn Output - This provides a 0-9 second ground during ringing through Q7. JU7 (pads A
and B) must be installed and JU8 (pads A and C) must be uninstalled.
P1-8 – Green/White
– PTT Hang Time Out – Connect to the radio’s PTT Input. This will keep the repeater keyed
after a loss of COR for the time set in the Hang Time.
P1-5 – Blue
– Alert Tone/Speaker Audio – Connect to high side of the speaker. This provides a decode
indication tone. When using 20-40 Ohm speakers, the onboard resistor in series with Q3 should be sufficient.
When attaching this lead to a 4-8 Ohm speaker, add a 100-Ohm resistor in series with the lead to limit current.
P1-12 – Orange/White
– Monitor/Program In – This input is connected for programming when the unit is plugged
into the KL-4F programming interface.
HARDWARE ALIGNMENT
RX Audio Input:
On the BTD-2 adjust R65 so that Pin 14 of U2 (TP1) doesn’t quite clip when a 1 KHz tone
modulated at 3.3 KHz deviation from a signal generator is applied. If more level is needed remove R63 by cutting
JU1. Additionally, with an oscilloscope a symmetrical and clean square wave should be seen at Pin 8 of U2 (TP4).
COR/COS:
If the radio only makes a minute change, it may be necessary to adjust the following values to cause
Q1 to change states:
R-5, R-6, & R-69
