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MAXON
SP-300 HAND HELD
Page -22-
May 2001
15. Disconnect the test equipment.
Should repairs be required, the following procedures should
be applied:
RX VCO
1. Set the unit to the highest receive frequency, 470
MHz(UHF), 174MHz(VHF) and adjust the VCO
L303 to 10 volts.
2. Set the unit to the lowest receive frequency 440
MHz(UHF), 148(VHF) and check that the VCO
voltage is above 2.0 volts. Adjust L303 for 2.0
volts.
z
Note: Use TP1 to measure the voltage.
RECEIVER
1. Apply a standard test signal to the receiver antenna
terminals.
2. Adjust T1 for maximum sensitivity and audio out-
put with minimum audio distortion.
TRANSMITTER
Connect the unit to a Service Monitor with the power meter
setting to the 10 W scale (or autorange).
TCXO
Set the channel selector to the mid-range frequency 460
MHz, adjust TC701(VHF) on the TCXO board, RV5 (UHF)
on the Main board, for a reading of 460 MHz +/-200 Hz (155
MHz VHF models).
TX VCO
1. Set the unit to the highest transmit frequency, 470
MHz(UHF), 174MHz(VHF) and adjust the VCO
L203 to 10 volts.
2. Set the unit to the lowest transmit frequency 440
MHz(UHF), 148(VHF) and check that the VCO
voltage is above 2.0 volts. If voltage is below 2.0
volts, adjust L203 for 2.0 volts or more.
CTCSS, DCS & DEVIATION ALIGNMENT
1a. Set the unit to a mid-frequency range and a CTCSS
of 67Hz. Push PTT and adjust RV403 for desired
CTCSS tone deviation.
1b. Switch to a channel with the same frequency and
CTCSS of 250.3Hz. Push PTT and adjust RV401 to
desired CTCSS tone deviation, same as above step.
1c. Switch between the 67Hz channel and the 250.3Hz
channel and adjust RV401 until the deviation is the
same on both channels. It may be necessary to read-
just RV403 to get the desired deviation.
2. Inject a 6mV signal of 1000Hz to the microphone
input. This should produce a 3kHz deviation for
25kHz(S) channel spacing and 1.5kHz for
12.5kHz(N) channel spacing, measure transmit dis-
tortion, that should be less than 5%. Increase the
audio input level to 20mV.
3. Set the deviation by adjusting RV402 to 4.5kHz for
25kHz channel spacing(S) and to 3kHz for 12.5kHz
channel spacing(N) on a non-CTCSS or DCS chan-
nel for the initial setting. Select a CTCSS or DCS
frequency and verify that the deviation is less than
or equal to 5kHz(S) and 3kHz(N).
4. Vary the audio frequency from 300 to 3000Hz and
verify that the deviation does not exceed 5kHz(S)
and 3kHz(N).
APC
1. Select a channel which is programmed with high
power. While transmitting, adjust RV1 in the APC
circuit for 5 watts +/- 0.1 watt.
2. Select a channel which is programmed with low
power. While transmitting, adjust RV3 in the APC
circuit for 1watt +/-0.1 watt.