Pacific Research Solutions RI-300e User Manual
Page 11
SECTION 4 INSTALLATION (RI-300)
If you are installing the RI-310 into the Vertex repeater, you can
skip to the next section.
This section will cover connecting your RI-300 to your repeater in
detail. To ensure a successful installation, please follow these few
simple steps.
1. Review this section completely and plan you repeater interface
before you start making connections.
2. Review section 7 of this manual for detailed information on
making audio level adjustments.
The diagram on the right is an end view of the radio interface
connector on your RI-300. Use the supplied DB-15S female
connector for making all connections to the controller.

PROPER TECHNIQUES FOR QUALITY REPEATER AUDIO

Obtaining good audio in any repeater is based on understanding the design of the equipment. The audio in all frequency
modulation (FM) transmitters or phase modulation (PM) transmitters has what is known as audio pre-emphasis. Pre-emphasis
means that with increasing audio frequency the amount of the modulation will increase. The reverse is performed in all FM
receivers and is called de-emphasis. The RI-300 was designed to operate with flat audio response from the repeater receiver
and transmitter. This means that neither de-emphasis nor pre-emphasis of the audio is performed on the repeat audio path. This
leaves all of the emphasis filtering in the user's radio. The RI-300 controller does include a low pass filter that rolls off the very
high audio frequency content to prevent adjacent channel splatter. The ideal interface between the RI-300 and a FM modulator
is one in which a varactor diode is directly driven. However, the RI-300 does have a de-emphasis filter that can be turned on
for those applications where you may need to interface to a modulator with pre-emphasis. It is not advisable to drive the
microphone input on the transmitters. Most transmitters have significant audio shaping, compensating for the microphone
response and other characteristics. The input connections to the RI-300 must be connected directly to the receiver’s
discriminator for the squelch to work properly. On some receivers, this connection can be made to the squelch circuit input.