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SERVICE MANUAL Maxon America, Inc. 10828 N.W. Airworld Dr. Kansas City, MO 64153 Tel: 816-891-6320 Fax: 816-891-8815 Part Number: 680-100-0155 April 2001...
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12.5 kHz ..........< 40 dB SP-300 HAND HELD and suitable antenna VHF: <...
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MAXON SP-300 HAND HELD RX TONE DEMODULATION CHARACTERISTICS SUBAUDIO TONES - CTCSS Tone Range ......... . . 67 Hz to 250.3 Hz Non-Standard Tones .
INTRODUCTION SP-300 The SP-300 Series of portable radios from Maxon, utilizes the latest technology in its design and manufacturing. Both the VHF and UHF models are PLL (Phase Lock Loop Syn- thesizer) / microprocessor controlled, and offer 1 or 5 watts of power with 4 &...
Memory Protect The software is such that if the radio is inadvertently put into program mode it will not lose the contents of the EEPROM memory. Data will only move in and out of the memory when the programmer is attached.
The controls, indicators and antenna connections on the VHF and UHF Scanning Handheld Series radios are all located on the top panel. The accessories socket is located on the radio chassis right hand side. The monitor and PTT buttons are located on the radio chassis left hand side.
Pin 14 (IC411). The filtered encode signal is fed to IC406B and RV403 (sub-audible gain control), the output of IC406B is then fed to the audio mixer circuit. SP-300 HAND HELD External Mic/PTT Control Circuit The external microphone is connected via the CON701 con- nector on the right side of the handheld.
MAXON SP-300 HAND HELD Mute (squelch) Circuit The mute circuit which is controlled by the output of IC409 (micro) Pin 77 (386EN) is connected to Q34 via R122 which mutes the LM386IC on the RF circuits. Pin 77 also controls IC402B which mutes the audio path to the RF circuits.
(2-11v). L203/L303 are resonant coil, which changes the control voltage by the tuning core. D202 modu- lation diode, modulates the audio signal. C204 compensate SP-300 HAND HELD for the non-linearity of the vco due to modulation diode, and maintain a constant modulation regardless of frequency.
MAXON SP-300 HAND HELD filters provide the adjacent channel selectivity of 25 kHz or 12.5 kHz bandwidth. Squelch (mute) Circuit The squelch circuit switches off the power amplifier when no audio signal is present. The squelch circuit consists of a 16 kHz band pass filter and a noise detector circuit.
1. With the slides of the belt clip positioned in line with the belt clip guide rails, slide the belt clip into posi- tion until a click is heard. SP-300 HAND HELD Figure 1-Belt Clip Removal Figure 2-Belt Clip Installation...
To replace the battery: 1. Position the battery on the battery guide rail at the bottom of the radio. 2. Move the top of the battery toward the radio until a click is heard. REMOVING & REPLACING PTT ASSY. To remove the PTT assembly: 1.
To replace the Control Knobs: 1. Reverse the steps taken to remove the Control Knobs. SP-300 HAND HELD Figure 5-PTT Installation Figure 6-A/C Removal & Installation Figure 7-Control Knob Removal & Installation...
MAXON SP-300 HAND HELD REMOVING & REPLACING THE BACK COVER To remove the Back Cover: 1. Remove battery. (Refer to Removing &Replacing the Battery) 2. Unscrew the four Back Cover mounting screws located on the Back Cover of the radio.
Note: It is not necessary to remove the stud mount antenna jack from the radio. 11. Remove the Speaker wire connector from the Main Board connector. SP-300 HAND HELD Figure 9-Main Board Removal & Installation Figure 9A-Main Board Removal & Installation Figure 9B-Main Board Removal & Installation...
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MAXON SP-300 HAND HELD To replace the Main Board 1. Reverse the steps taken to remove the Main Board. 2. When installing the Main Board into the chassis insure that the LED light guide is aligned properly. 3. When installing the Main Board into the chassis,...
3. When the solder on all terminals is liquefied, gently remove the component. Excessive force may cause the PCB pads to separate from the board if all sol- der is not completely liquefied. Page -19- May 2001 MAXON SP-300 HAND HELD...
MAXON SP-300 HAND HELD 4. It may be necessary to remove excess solder using a vacuum de-soldering tool or Solder wick . Again, use great care when de-soldering or soldering on the printed circuit boards. It may also be necessary...
8. For cloning other radios, repeat steps 3 through 7. SP-300 HAND HELD ALIGNMENT PROCEDURE The SP-300 U/V Receiver is by design, broad band, cover- ing UHF(440 to 470 MHz) and VHF(148-174MHz) and should require no special alignment, unless repairs are per- formed on the receiver portion.
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MAXON SP-300 HAND HELD 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.
TEST EQUIPMENT SETUP AUDIO GENERATOR RADIO DC POWER SUPPLY RADIO DC POWER SUPPLY 1. S.S.G. : @ 1kHz Audio: SP-300 HAND HELD WATT METER 20dB AUDIO MODULATION- METER OSCILLOSCOPE SPECTRUM ANALYZER 154.625445681125661 FREQUENCY COUNTER VOLT METER 3K Dev @ 1K (25 kHz Channel Spacing) 1.5K Dev @ 1K (12.5 kHz Channel Spacing)
MAXON SP-300 HAND HELD CONTROL CIRCUIT REF # Q401 Q403 Q404 Q405 Q406 Q407 Q408 Q410 Q411 Q412 Q413 NOTE: Q402 and Q409 are not fitted on this model series. MAIN CIRCUIT REF # 18.0 18.0 ~3.0 NOISE NOTE: Q9, 10, 15, 19, 20, 23 and 28 - 32 are not fitted on this model series.
NOTE: IC4, 403 and 405 are not fitted on this model series. IC401 AUDIO AUDIO IC407 IC408 IC410 IC411 AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO AUDIO Page -27- May 2001 MAXON SP-300 HAND HELD IC402 AUDIO...
MAXON SP-300 HAND HELD SP-300 SERIES UHF RF SECTION PARTS LIST REF # DESCRIPTION REPLACEMENT MODULES FRONT ENDASSY, UHF (SEE NOTE 1) VCOTX/RX ASSY, UHF (SEE NOTE 1) POWERAMPASSY, UHF (SEE NOTE 1) COMPONENTS CAP,CER,470PF,10%,50V,X7R,0603 CAP,TA,10UF,293D106X06R3A2T6.3V CAP,CER,470PF,10%,50V,X7R,0603 CAP,CER,470PF,10%,50V,X7R,0603 CAP,CER,470PF,10%,50V,X7R,0603 CAP,TA,4.7UF,20%,10V,3216...
SQ IN INPUT MUTE AF OUT FIL IN FIL OUT FAST INTEGRATER NOISE AMP AF LEVEL LM386 AUDIO AMP REVISIONS DESCRIPTION DESCRIPTION 03/01 TITLE SP-300 Series SYSTEM ELECTRICAL BLOCK DIAGRAM DOCUMENT SIZE 060-***-**** NUMBER SCALE SHEET PAGE -47- May 2001...
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