AAO2101845

1 OWNER’S MANUAL FRS RADIO 21-1845 INTRODUCTION With RadioShack’s base station FRS radio, you can stay in constant communication with your family throughout your home. In addition, they’re great for office use as well. Your radio has 14 channels and 38 different QUIET codes. If someone else is using the channel you selected and you do not want to hear that person, select another channel, or use the QUIET feature. You can talk with a person who has a FRS radio if both radios are tuned to the same channel and QUIET code. Your radio has auto-squelch, which means you will not hear anything on a channel unless someone is transmitting nearby on the same channel. You can turn off auto-squelch to hear weaker, distant transmissions. You can connect an optional speaker/microphone and earphone to the radio. The VOX operation brings you convenient hands-free use. Your transceiver has these features: Selective Channel and QUIET ---- You can select the channel from one of the 14 FRS channels and one of the 38 QUIET by using two arrays of dip switches. PLL Controlled Circuitry ---- provides accurate and stable channel selection. QUIET (Continuous Tone Control Squelch System) ---- helps reduce interference from other systems in the area operating on the same frequency. Built-in Modulation Limiter Circuit ---- automatically adjusts for a wide variety of voice levels to ensure an understandable transmission. External Earphone and Microphone ---- Let you transmit or receive message by pressing or releasing Push-To-Talk button on the headset or use VOX option for hands-free operation. Fixed Telescopic Antenna ---- Let you have a better performance of communication. We recommend you record your transceiver’s serial number here. This number is on the transceiver’s back panel. Serial Number_______________________ 2 Your transceiver might cause TV or radio interference even when it is operating properly. To determine whether your transceiver is causing the interference, turn off your transceiver. If the interference goes away, your transceiver is causing it. Try to eliminate the interference by: • Moving your transceiver away from the receiver. • Contacting your local RadioShack store for help. FUNCTION AND LOCATION OF THE CONTROLS 1. Volume Control. Rotate this control rightwards to turn on your radio and adjusts the volume, until you get a comfortable listening level. 2. CALL You can cause a ringer sound on all radios tuned to the same FRS channel and/or the privacy code as your radio. To send a page, press and hold down the CALL button. 3. Talk button To talk, hold down the Talk. Speak into the microphone in a normal tone of voice when the TX indicator lights. When you finish speaking, release the Talk button. 3 4. VOX Button To active/deactivate VOX function, press and release the VOX button. When VOX on led indicator lights, it indicates the VOX function is activated. When VOX function is activated, the unit transmitter will automatically be opened when the user speaks. It will continue to transmit until the user finishes. Then, the unit will go into the receive mode. 5. VOX Sensitivity Rotary this control to adjusts the VOX sensitivity. When there is too much background noise, it is better to turn this control leftwards to select Lo sensitivity. 6. Transmit LED Indicator It will light when you transmit. 7. Power LED Indicator It will light when the unit is turned on. 8. VOX LED Indicator When VOX on led indicator lights, it indicates the VOX function is activated. 9. MON Button To hear everything happening on a channel, including weak transmission, hold down MON button. Release the MON button to turn the auto-squelch back on. 10. External Mic/Spk Jack Connect an optional speaker/microphone or earphone in this jack. 11. Power Jack Just plug the station into the DC outlet of included DC adapter, then connect the adapter to a standard AC outlet. 12. Fixed Telescopic Antenna Adjust antenna will let you have a better performance of communication. 13. Two arrays of dip switches (at the bottom) Let you select one channel from 14 FRS channels and one of 38 QUIET frequencies by using these two arrays of dip switches. 4 SETTING CHANNEL FREQUENCIES AND CTCSS CODES On the station bottom, you will find two arrays of dip switch. These switches are used to set the channel frequency, and CTCSS code.
Setting for 38 CTCSS Code The first array of 6-digit dip-switch is used to set 38 CTCSS codes. Please find below table for setting. CTCSSCTCSS CodeFreq.(Hz) Dip Switch Setting CodeFreq.(Hz) Dip Switch Setting without CTCSS000000 0167.000000120131.8010100 0271.900001021136.5010101 0374.400001122141.3010110 0477.000010023146.2010111 0579.700010124151.4011000 0682.500011025156.7011001 0785.400011126162.2011010 0888.500100027167.9011011 0991.500100128173.8011100 1094.800101029179.9011101 1197.400101130186.2011110 12100.000110031192.8011111 13103.500110132203.5100000 14107.200111033210.7100001 15110.900111134218.1100010 16114.801000035225.7100011 17118.801000136233.6100100 18123.001001037241.8100101 19127.301001138250.3100110 5
Setting for Channel Frequencies The second array of 4-digit dip switch is used to set any one of the 14 channel frequencies. Please find below table for setting. Dip Switch SettingChannelFrequency (MHz) 0000FRS 1462.5625 0001FRS 1462.5625 0010FRS 2462.5875 0011FRS 3462.6125 0100FRS 4462.6375 0101FRS 5462.6625 0110FRS 6462.6875 0111FRS 7462.7125 1000FRS 8467.5625 1001FRS 9467.5875 1010 FRS 10467.6125 1011 FRS 11467.6375 1100 FRS 12467.6625 1101 FRS 13467.6875 1110 FRS 14467.7125 1111 FRS 14467.7125 C. OPERATION 1. Plug the station with 9VDC 500mA adapter for power. 2. Rotate volume control to turn on the radio. Press the MON button and adjust to a comfortable listening level. 3. Press the Talk button to transmit or use VOX option for hands-free. The TX indicator lights green. 4. Select the desired channel and/or QUIET code. 5. To receive, simply release the Talk button. In VOX mode, the unit will receive…

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THEORY OF OPERATION 21-1845 This FRS transceiver provides accurate and stable operation. The basic functions consist of 8 main sections : ■ Power Supply Unit ■ Receiver Stage ■ Squelch Control ■ Transmit Stage ■ VCO and PLL ■ Micro-controller ■ CTCSS(QUIET) ■ CALL Power The unit is powered with an AC 117V adapter with output 9V DC. 1. 9V voltage is regulated to 5.0V by IC6 a low drop regulator LM2930 for the VCO & PLL power, as well as for CPU power, TX and RX power control circuitry. Q15 as a power switch for RX and TX. They are controlled by RX and TX CTL from CPU. 2. The power for the RF-power amplifier, is directly driven by 9V. 3. The power for the Audio amplifier section. Receive Stage RF signal is received through the antenna and is passed onto a low pass filter network and amplified by Q4. This allows only the required band signal to pass through to the SAW band pass filter (BPF) F1. The mixer Q5 converts the incoming signal down to 21.7MHz. This signal again passes to a 21.7MHz XTAL band pass filter F2. This gives a better channel selectivity. The selected 21.7MHz signal is amplified by IF amplifier Q6 before it is passed to the second converter IC2 MC3361. IC2 MC3361 is the second converter. This converts the 21.7MHz signal down to 450KHz. This 450KHz signal is sent to discriminator. The detected audio signal passes through Audio Amplifier unit IC8 LM324, the 300Hz high pass filter and volume control. The audio signal then is amplified by audio amplifier IC10 LM368, and then fled to the speaker. Squelch Control Squelch control circuitry consists of IC2 MC3361 and its related circuit. The squelch signal output from IC2 pin 9 pass through filter amplifier circuit composed by pin 10 and pin 11. The signal is amplified and detected by IC2 and generate a control voltage at pin 13 of IC2 for CPU to detect. VR1 is used to control the threshold of the squelch (squelch sensitivity). Pin 13 of IC2 is output a Lo to MCU IC5 pin 51 to indicate an incoming signal is detected. Transmit Stage When the PTT switch goes down, the transceiver is switched into transmit mode through the TX/RX exchange control. Q15 is turned on for the power to the transmitter. The voice is picked up by the condenser MIC and passes through the 300Hz high pass filter IC3 NJM3403 and is amplified by IC4 LM324 MIC amplifier circuit. The signal modulates with the carrier in the form of FM modulation. The modulated signal from the VCO goes into the power amplifier unit which consists of a buffer amplifier Q8, a driver amplifier Q7 and the RF power amplifier Q3. The signal then is finally radiated out through antenna. VCO and PLL PLL circuitry is composed of IC1 M64082 the high frequency PLL and VCO. The channel information from the CPU is sent to the shift register in IC1 from pin 2. A control voltage is generated through the low pass filter to the VCO from pin 8 and is used to control RF frequency from Q1. Q9 is the RX/TX exchange switch. RF signal from the VCO passes through the buffer amplifier Q2 and then is fed into PLL IC1. In receive mode, the signal is fed to the receiver first mixer Q5 to convert the received signal to 21.7MHz. In transmit mode, this signal modulations with the audio signal and is passed through to the transmit power amplifier unit for transmission. Microcontroller The Microcontroller MPD789405 is the main control of the whole transceiver unit. It is also used to drive the LCD to show the status of the unit. On the LCD, there is current working channel display, transmit indication, receive indication, QUIET indication, and low battery indication. The MCU scans the keypad to detect key pressed and released, then execute the function accordingly. CTCSS(QUIET) The CTCSS consists of transmit and receive section. In CTCSS transmit, a CTCSS signal is added to the audio and modulated for transmission. CPU pin OUT1, OUT2, OUT3 and OUT4 output a 16 stage of digital values. These digital values then are passed through a digital to analog converter R164 to R171. The output is a step waveform, and then is filtered by a low pass filter and mixed with the audio. The receive section consists of a CTCSS decoder circuit which is used to separate the audio signal and a CTCSS signal for the existing of a CTCSS signal. The CTCSS signal is filtered and amplified by IC2 MC3361 and reshaped as a square wave by IC9 LM324. The signal then is input to the CPU and is determined the CTCSS singal value for the valid CTCSS received. The unit CTCSS (QUIET) code is selected by the combination of CTCSS switches P40,P41,P42,P43,P44 and P45 input to MCU IC5. CALL When the CALL button is pressed, the transceiver is switched into transmit mode through the CPU control. IC306 MC14001 generates a ringer audio signal which is controlled by CPU. This 1.6KHz signal is amplified in the MIC amplifier unit and modulated for transmission. ADJUSTMENT PROCEDURE STEPITEMADJUSTMENTPROCEDURE 1TX FrequencyVC1Adjust VC1 to obtain demanded TX frequency. 2TXL11 L12 L13 Adjust L11, L12, L13 to obtain demanded TX power. 3TX. Dev. VR31. Inject an audio frequency (AF) -20dBm. 2. Adjust VR3 to obtain maximum TX deviation ≤2.5KHz. 3. Check MIC modulation sensitivity, and it should be 2.5~10mV. 4CTCSS Dev.Check CTCSS deviation if it is normal. 5RXCheck RX sensitivity if it is normal. 6RXL5 L1 Adjust L5 and L104 to obtain Max. Sensitivity. 7RXVR1Adjust VR1 to obtain demanded squelch sensitivity. ALIGNMENT PROCEDURES Important: The FCC requires that any frequency adjustment on a radiophone must be done by authorized person, who is the holder of a current first or second class radiotelephone license. This unit has been fully aligned at the factory before shipment and does not normally require further adjustment. When necessary, however, the unit may be aligned as indicated below. Do not adjust any circuit in this radiotelephone unless you understand the circuit operation and have experience in adjusting radiotelephone. Tampering with the radiotelephone may ups…

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ADJUSTMENT PROCEDURE STEPITEMADJUSTMENTPROCEDURE 1TX FrequencyVC1Adjust VC1 to obtain demanded TX frequency. 2TXL11 L12 L13 Adjust L11, L12, L13 to obtain demanded TX power. 3TX. Dev.VR31. Inject an audio frequency (AF) -20dBm. 2. Adjust VR3 to obtain maximum TX deviation ≤2.5KHz. 3. Check MIC modulation sensitivity, and it should be 2.5~10mV. 4CTCSS Dev.Check CTCSS deviation if it is normal. 5RXCheck RX sensitivity if it is normal. 6RXL5 L1 Adjust L5 and L104 to obtain Max. Sensitivity. 7RXVR1Adjust VR1 to obtain demanded squelch sensitivity. ALIGNMENT PROCEDURES Important: The FCC requires that any frequency adjustment on a radiophone must be done by authorized person, who is the holder of a current first or second class radiotelephone license. This unit has been fully aligned at the factory before shipment and does not normally require further adjustment. When necessary, however, the unit may be aligned as indicated below. Do not adjust any circuit in this radiotelephone unless you understand the circuit operation and have experience in adjusting radiotelephone. Tampering with the radiotelephone may upset the alignment and lower its performance. Test Equipment Required The following equipmentis requred for the alignment. Regulated DC power supply, 0~12V,1A or higher. Audio signal generator,10Hz~3KHz Digital multimeter Deviation meter Frequency counter,0~500MHz high impedance Oscilloscope RF power meter, 0.5W High frequency standard generato,>500MHz Tracking generator,>500MHz Distortion analyzer Audio level meter T-coupler Alignment drivers, etc.

ENGINEERING STATEMENT For Type Certification of Radio Shack; a Division of Tandy Corporation Model No: 21-1845 FCC ID: AAO2101845 I am an Electronics Engineer, a principal in the firm of Hyak Laboratories, Inc., Springfield, Virginia. My education and experience are a matter of record with the Federal Communications Commission. Hyak Laboratories, Inc. has been authorized by Radio Shack; a Division of Tandy Corporation, to make type certification measurements on the 21-1845 transceiver. These tests made by me or under my supervision in our Springfield laboratory. Test data and documentation required by the FCC for Type Certification are included in this report. The data verifies that the above mentioned transceiver meets FCC requirements Type Certification is requested. ______________________________ Rowland S. Johnson Dated: November 29, 1999 A. INTRODUCTION The following data are submitted in connection with this request for type certification of the 21-1845 transceiver in accordance with Part 2, Subpart J of the FCC Rules. The 21-1845 is a portable, battery operated, UHF, frequency modulated transceiver intended for 12.5 kHz channel family radio service applications in the 462.5625-467.7125 MHz band. It operates from a 117 Vac supply. Output power rating is 0.5 watts ERP. B. GENERAL INFORMATION REQUIRED FOR TYPE CERTIFICATION (Paragraph 2.983 of the Rules) 1. Name of applicant: Radio Shack, a Div. of Tandy Corp. 2. Identification of equipment: FCC ID: AAO2101845 a. The equipment identification label is a separate exhibit. b. Photographs of the equipment are included as a separate exhibit. 3. Quantity production is planned. 4. Technical description: a. 11k0F3E emission b. Frequency range: 462.5625 - 467.7125 MHz. c. Operating power of transmitter is fixed at the factory 0.5 W ERP. d. Maximum power permitted is 0.5 watts, and the 21- 1845 fully complied with that power limitation. e. The dc voltage and dc currents at final amplifier: Collector voltage: 5.8 Vdc Collector current: 130 mA f. Function of each active semiconductor device: See Appendix 1. g. Complete circuit diagram is submitted as a separate exhibit. h. A draft instruction book is submitted as a separate exhibit. i. The transmitter tune-up procedure is included as a separate exhibit. 2 B. GENERAL INFORMATION REQUIRED FOR TYPE CERTIFICATION (continued) j. A description of circuits for stabilizing frequency is included in the Theory of Operation. k. A description of circuits and devices employed for suppression of spurious radiation and for limiting modulation is included in the Theory of Operation. l. Not applicable. 5. Data for 2.985 through 2.997 follow this section. C. RF_Power_Output (Paragraph 2.985(a) of the Rules) The 21-1845 has a permanently attached built-in antenna without provisions for a coaxial connector. Therefore RF power output was calculated as shown in Table 1. (The transmitter was tuned by the factory according to the procedure of Exhibit 4.) TABLE 1 Operating Freq., MHz Power watts into a dipole antenna 462.5625 0.49 D. MODULATION CHARACTERISTICS 1. A curve showing frequency response of the transmitter is shown in Figure 1. Reference level was audio signal output from a Boonton 8220 modulation meter with one kHz deviation. Audio output was measured with a Audio Precision System One integrated test system. 2. Modulation limiting curves are shown in Figure 2, using a Boonton 8220 modulation meter. Signal level was established with a Audio Precision System One integrated test system. The curves show compliance with paragraphs 2.987(b). 3 D. MODULATION CHARACTERISTICS (continued) 3. Figure 3 is a graph of the post-limiter low pass filter which provides a roll-off of 60Logf/3 dB where f is audio frequency in kHz. Measurements were made following EIA RS-152B with an Audio Precision System One integrated test system on the Boonton 8220 modulation meter audio output. 4. Occupied_Bandwidth (Paragraphs 2.989(c) of the Rules) Figure 4 is a plot of the sideband envelope of the transmitter output taken with a Tektronix 494P spectrum analyzer. Modulation corresponded to conditions of 2.989(c)(1) and consisted of 2500 Hz tone at an input level 16 dB greater than that necessary to produce 50% modulation at 2380 Hz, the frequency of maximum response. Measured modulation under these conditions was 2.2 kHz. The plots are within FCC limits. The horizontal scale (frequency) is 10 kHz per division and the vertical scale (amplitude) is a logarithmic presentation equal to 10 dB per division. Unmodulated carrier reference is 0 dBm. E. SPURIOUS EMISSIONS AT THE ANTENNA TERMINALS (Paragraph 2.991 of the Rules) The 21-1845 has a permanently attached antenna. There is no connector for an external antenna. Therefore, no antenna terminal conducted measurements were made. F. DESCRIPTION OF RADIATED SPURIOUS MEASUREMENT FACILITIES A description of the Hyak Laboratories' radiation test facility is a matter of record with the FCC. The facility was accepted for radiation measurements from 25 to 1000 MHz on October 1, 1976 and is currently listed as an accepted site. 4 FIGURE 1 MODULATION FREQUENCY RESPONSE MODULATION FREQUENCY RESPONSE FCC ID: AAO2101845 FIGURE 1 5 FIGURE 2 AUDIO LIMITER CHARACTERISTICS AUDIO LIMITER CHARACTERISTICS FCC ID: AAO2101845 FIGURE 2 6 FIGURE 3 AUDIO LOW PASS FILTER RESPONSE AUDIO LOW PASS FILTER RESPONSE FCC ID: AAO2101845 FIGURE 3 7 FIGURE 4 OCCUPIED BANDWIDTH ATTENUATION IN dB BELOW MEAN OUTPUT POWER Required On any frequency more than 50% up to and including 100% of the 25 authorized bandwidth, 12.5 kHz (6.25-12.5 kHz) On any frequency more than 100%, up to and including 250% of the 35 authorized bandwidth (12.5-31.25 kHz) On any frequency removed from the assigned frequency by more 43+10LogP = 40 than 250% of the authorized (P = 0.49W) bandwidth (over 31.25 kHz) OCCUPIED BANDWIDTH FCC ID: AAO2101845 FIGURE 4 8 G. FIELD STRENGTH MEASUREMENTS OF SPURIOUS RADIATION Field intensity measurements of radiated spuriou…

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