CES SUPPORT 407-679-9440
Page 12
MAN79 © CES 2009
2.12 Level Adjustments
RX Audio
Inject a signal modulated with a 1 kHz tone at 4 KHz deviation into the receiver. Adjust R37 for 500 mV p-p at
TP2. If this level is difficult to obtain, install or remove JP4 as follows. If level at TP2 below the 500 mV and R37
is at maximum, install JP4. If level is too sensitive at TP2 remove JP4 (factory default) and readjust.
Internal COR mobile detector
This adjustment sets the threshold for the RM-20s internal squelch circuit. This setting is critical for proper
operation of the RM20. Apply power to the RM-20 and radios. Disable the transmitter via TX disable switch on the
front panel of the RM-20. Then turn R23 clockwise until the COR LED (DS2) illuminates, then turn R23
counterclockwise
just
until the COR LED extinguishes. Generate carrier to the receiver and verify that COR LED
illuminates when carrier is present and extinguishes when carrier is removed. The COR is now set correctly.
Note: Not required if external COR is used for carrier detection
TX / Repeat Audio
Inject a signal modulated with a 1 kHz tone at 4 kHz deviation into the receiver, and with TP2 adjusted to 500 mV
p-p (175 mV rms.) adjust R69 for 4 KHz deviation measured with a deviation meter or service monitor on the
transmitter frequency. If this level is difficult to obtain, install or remove JP5 as follows. If deviation is above 4 KHz
and R69 is at minimum, remove JP2 (factory default). If deviation is below 4 KHz and R69 is at maximum install
JP2 and readjust.
Roger Beep (if enabled)
Apply and remove carrier to the receiver and listen for the beep. If adjustment is needed, repeatedly apply and
remove carrier in to the receiver to activate the beep. Adjust R40 until the desired level is obtained.
CTCSS RX
This level is also controlled with R37 (RX audio level control) and theoretically the RX Audio adjustment procedure
above should be sufficient. However in cases where not enough audio level is obtained at TP2, increasing R37 will
bring this level to a reliable operating range. The microprocessor will accurately decode CTCSS from 100 mV to 2v
p-p. It is suggested that the input level at TP2 be kept at between 500 to 750 mV p-p.
Note: R
ECEIVE AUDIO MUST BE CONNECTED TO THE DISCRIMINATOR OF THE RECEIVER FOR THIS FEATURE TO OPERATE
.
CTCSS TX
A CTCSS TX tone must be programmed prior to performing this adjustment. (Refer to the programming section on
this manual). Apply carrier to the receiver and monitor the transmitter frequency. Adjust R25 for 800 Hz deviation.
If this level is difficult to obtain install or remove JP2 as follows: if not enough CTCSS signal is obtained with R25
at maximum, install JP2. If the adjustment is too sensitive, remove JP2 (factory default) and readjust.
