User's Manual

Page Center User Manual
Page 37
12 Alignment
12.1 Adjustments
The following table lists the internal adjustments.
Reference
Designator
Function
R9 Squelch/carrier detect threshold level.
R20 Receive audio level.
R16 RX audio bias.
R32 CTCSS encode level. Adjust for 10% of full-system deviation w/CTCSS encoder on.
R34 Paging data level. Adjust for 90% full system deviation w/POCSAG data being transmitted.
R41 Voice limiter. Adjust for 95% full system deviation with loud audio into the mic.
R60 Mic gain. Adjust for proper mic audio level.
R52 Telco audio to transmitter level. Adjust for proper voice deviation of the transmitter with
signal from the telephone interface.
R69 Telco line driver level. Adjust for proper level to the telephone from the received audio.
12.2 Test Procedure
12.2.1 General Setup
1. Apply DC power to the unit. Connect the service monitor to the ANT port.
2. Download the Flash code to the unit if it is not already programmed. Hold down the "-" key while
powering up the unit to enter Flash code programming mode. See the section on "Firmware Updating" for
additional information.
3. Adjust the LCD contrast control on the rear panel of the unit.
12.2.2 Radio Interface
This procedure assumes a properly tuned transceiver is installed in the unit. You will need a DC power source,
service monitor, oscilloscope, and DVM. Full System Deviation =5.0 kHz for wide-band versions, and
FSD=2.5 kHz for narrow-band versions. Depending upon the type bandwidth of the transceiver used, you will
have to make slightly different adjustments.
1. Program the unit’s transmit and receive frequencies. Disable sub-audible signaling.
2. Set the TX bandwidth to “wide band” or "narrow band" depending on the bandwidth of the transceiver unit
installed.
3. Generate an RF carrier on the receive frequency, 1 kHz tone, 60% FSD = 3 kHz / 1.5 kHz. RF level 10 uV.
4. Adjust R16 for a 1.5 V p-p (530 mV RMS) signal on TP8.
5. Adjust the RF generator to .35 uV. Adjust R9 so that the carrier detect LED is on, and so that it goes off
when the RF level is below .25 uV.
6. Set the speaker volume level to normal level (about 25% full volume).
7. Set the service monitor to measure the transmitter's FM deviation. Key the transmitter using the F3 key.
8. Adjust R160 so the carrier is on frequency.
9. Blow into the microphone strongly and adjust R41 (limiter) for 4.5 kHz / 2.25 kHz maximum deviation.
10. Adjust R60 (mic gain) for 3 kHz / 1.5 kHz deviation when speaking into the mic with a normal voice level
from a distance of about 1 foot away.