Cat. No. 19-1126 OWNER’S MANUAL HTX-242 TWO-METER MOBILE TRANSCEIVER Please read before using this transceiver.
INTRODUCTION Your HTX-242 Two-Meter Mobile Transceiver is an exciting addition to Radio Shack’s growing line of high-quality amateur radio equipment. It offers some of the most advanced, and most requested, features available in a mobile transceiver. Be sure to read this entire manual to understand how to use all the radio’s features. ! You must have a Technician Class or higher Amateur Radio Operator’s License and a call sign issued by the FCC to legally transmit using this transceiver.
Programmable Frequency Step—lets you set the frequency step for tuning or scanning to 5, 10, 12.5, 20, 25, 50, or 100 kHz. Extended Band Coverage —receives from 136 to 174 MHz and lets you extend transmit coverage to include 2-Meter ham, MARS (Military Amateur Radio Service), and CAP (Civil Air Patrol). Dual VFO (Variable-Frequency Oscillator) and Duplex Modes— two independent VFOs let you quickly select between two directlyentered frequencies.
CONTENTS Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Unpacking the Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . 6 Connecting the Microphone . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mounting the HTX-242 in a Vehicle . . . . . . . . . . . . . . . . . . . 7 Connecting an Antenna . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 Connecting to your Vehicle’s Power . . . . . . . . . . . . . . . . . . .
Advanced Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Frequency Offset Defaults . . . . . . . . . . . . . . . . . . . . . . . . . Turning Auto Duplex On and Off . . . . . . . . . . . . . . . . Changing the Default Offset . . . . . . . . . . . . . . . . . . . . Reversing the Offset . . . . . . . . . . . . . . . . . . . . . . . . . . Overriding the Duplex Offset . . . . . . . . . . . . . . . . . . . . Using the Dual VFOs for Duplex Operation . . . . . . . . . . . .
INSTALLATION Unpacking the Transceiver As you unpack the transceiver, check to be sure you have all the items shown in this illustration. Connecting the Microphone Plug the microphone’s connector into the microphone jack, secure the microphone holder to either the left or right side of the transceiver, then clip the microphone to the holder.
Mounting the HTX-242 in a Vehicle When you select a mounting location for the HTX-242, be sure: • You can easily reach it • No wires or cables will interfere with the vehicle’s operation • It is not directly in front of heating vents • All wires will reach their connection points Cautions: • To avoid damaging your vehicle’s electronic systems, contact your vehicle’s manufacturer before you install the HTX-242 to find out about the proper transceiver mounting locations, antenna locations, and power
Connecting an Antenna You can connect a variety of antennas for both mobile and basestation use (see “Using the HTX-242 as a Base Station” on Page 10). Each type of antenna has its benefits. Choose one that best meets your needs. When deciding on a mobile or base-station antenna and its location, consider the following: • The antenna should be as high as possible on your vehicle or house.
Connecting to your Vehicle’s Power Follow these steps to power the HTX-242 in your vehicle. 1. Connect the black wire to your vehicle battery’s negative (–) terminal or to a metal part of the vehicle’s frame. Be sure the metal part is not insulated from the vehicle’s frame by a plastic part. 2. Connect the red wire to a source of voltage that turns on and off with the ignition and that can handle the transceiver’s 10-amp maximum power draw.
Using the HTX-242 as a Base Station Although we designed the HTX-242 primarily for use as a mobile transceiver, you can also use it as a base station. To do so, you need these items: • 13.8-Volt DC regulated power supply that can supply at least 10 amps continuous power • Base station antenna • 50-ohm coaxial antenna cable and connectors Follow these steps to connect the HTX-242 as a base station. 1. Mount the base station antenna according to its instructions.
Using the HTX-242 with Packet Radio You can connect your HTX-242 directly to a packet radio terminal node controller, as shown below. Note: You can purchase an 8-pin plug that matches your HTX242’s MIC jack at your local Radio Shack store (Cat. No. 279-440). Connecting an External Speaker (Optional) You can connect an external speaker to your HTX-242. Use an 8-ohm communications or PA speaker that can handle 5 or more watts of power (such as Radio Shack Cat. No. 21-549).
UNDERSTANDING THE HTX-242 This section explains some of the HTX-242’s features. See “Basic Operation” on Page 16 for instructions about how to use these features. Dual VFO Modes The VFO (Variable-Frequency Oscillator) modes let you directly select a frequency anywhere within the HTX-242’s operating range. Your HTX-242 has two VFOs: VFO-A and VFO-B. You typically use the VFOs to tune to frequencies you have not stored into one of the HTX-242’s memory channels (see “Memory Channels” on Page 13).
Subaudible Tone (CTCSS) Features Subaudible tones, also known as CTCSS (Continuous Tone-Coded Squelch System) are low-frequency tones that are mixed with a transmission. They are used by many repeaters to limit interference from other nearby radio transmitters. When a repeater uses a subaudible tone, it does not react to any transmission that does not include that tone. Your HTX-242 includes all 38 standard subaudible tones. You can set your HTX-242 to include any of these tones with your transmissions.
Understanding the Display One or more of the following indicators appear when you turn on and use your HTX-242. VFO-A or VFO-B — appears when you select one of the VFO modes. See “Dual VFO Modes” on Page 12. VFO-A-T VFO-B — appears when you select the DUP-A mode (transmit on VFO-A and receive on VFO-B). See “Using the Dual VFOs for Duplex Operation” on Page 27. VFO-A VFO-B-T — appears when you select the DUP-B mode (receive on VFO-A and transmit on VFO-B).
+ or – — indicates the duplex offset direction. See “Overriding the Duplex Offset” on Page 26. DTMF — appears when you turn on DTMF squelch. See “Using DTMF Page” on Page 33. HIGH or LOW — indicates the transmit power level. See “Setting the Power Level” on Page 17. ON-AIR — appears when you transmit. See “Transmitting” on Page 22. — appears when you turn on the Channel 1 alarm. Flashes when there is a transmission on Memory Channel 1 and the alarm is turned on.
BASIC OPERATION Turning On/Off Your HTX-242 To turn your HTX-242 on or off, press POWER. When you turn it on, all display elements briefly turn on and the HTX-242 sounds five tones. Then it returns to the last-used settings. Resetting the HTX-242 When you first use your HTX-242, if it displays PLL Err or EEP Err, or if you ever want to reset the HTX-242 to the factory defaults and clear all memory, follow these steps. ! Important: This procedure clears all stored information. 1. Turn off the HTX-242.
Setting Volume and Squelch SQUELCH sets the minimum signal level that must be present for the HTX-242 to amplify the signal through the speaker or to stop when scanning. Follow these steps to set the squelch. 1. Rotate SQUELCH fully counterclockwise. 2. Set VOLUME so you can hear the background hiss between transmissions. Note: If you do not hear hissing, turn TUNE/M-CH to select a frequency that does not have communications in progress. 3. Slowly turn SQUELCH clockwise until the hissing stops.
Selecting a Frequency You can select a frequency in any of three ways: • Direct entry • Tuning • Scanning Directly Entering a Frequency 1. Press VFO to select either VFO-A or VFO-B. 2. Enter the last five digits of the frequency. For example, to enter 145.050, simply press 45050. Notes: ! • The HTX-242 rounds the last digit down to 5 or 0. • The HTX-242 does not accept entries outside its range.
Scanning for a Frequency 1. Press VFO to select either VFO-A or VFO-B. 2. Press F. Then press ▲ to scan up or ▼ to scan down. Notes: ! • You can set the HTX-242 to scan in 5, 10, 12.5, 20, 25, 50, or 100 kHz steps. The default is 20 kHz. See “Setting the Frequency Step” on Page 19. • You can program up to five frequencies for the HTX-242 to skip when scanning. See “Storing Scan Skip Frequencies” on Page 20.
Setting the Scan Options Storing Scan Skip Frequencies You can store up to five frequencies for your HTX-242 to skip when scanning. This lets you prevent the HTX-242 from stopping on beacon or packet repeater frequencies. 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR. The HTX-242 displays SC and the current scan resume setting. 4. Repeatedly press ▲ until the HTX-242 displays S1 and the first scan skip frequency (or –––.––– if no frequency is stored). 5.
Setting the Scan Resume Delay When you set the scan resume condition to cr (carrier), the HTX242 resumes scanning after the carrier drops. The scan resume delay option lets you set the HTX-242 to pause before resuming so you can hear replies. The factory default is 2 seconds. Follow these steps to change the scan resume delay. 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR. 4. Repeatedly press ▲ until the HTX-242 displays Sd and the current scan resume delay (0.
Receiving Transmissions To receive a transmission, turn on the HTX-242, adjust the volume and squelch, and tune to the frequency you want to monitor. The HTX-242 displays BUSY, and the signal-strength indicator shows the relative signal strength when it receives a signal. Note: If BUSY appears but you hear nothing from the speaker, be sure the DTMF page and tone-squelch features are turned off and SQUELCH is set correctly. To turn off DTMF page, press DTMF once.
Manually Transmitting DTMF Tones To transmit DTMF tones, follow the steps for transmitting. Then, while holding down PTT, press the digits on the microphone to transmit the tones. ! Note: If auto-reply is turned on, you must hold down PTT while you transmit. If auto-reply is off, you can release PTT after you enter the first digit. The HTX-242 transmits for 1 second after you enter the last digit. See “Using Auto-Reply” on Page 34. Transmitting DTMF Tones from Memory 1.
Limiting Transmit Duration When you communicate on the 2-meter band, you should keep your transmissions as brief as possible. Most repeaters have builtin timers that limit single transmissions to 3 minutes or less. You can set the transceiver to stop transmitting and sound a beep if a single transmission exceeds the selected time (none, 1, 2, 3, 5, 7, 10, or 15 minutes). Follow these steps to select the transmission time-out setting. 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3.
ADVANCED OPERATION Frequency Offset Defaults When you select a frequency, the HTX-242 defaults to the following frequency offsets if auto duplex is turned on: Receive Frequency Below 144.600 MHz 144.600 to 144.905 MHz 144.910 to 145.205 MHz 145.210 to 145.505 MHz 145.510 to 146.005 MHz 146.010 to 146.375 MHz 146.380 to 146.605 MHz 146.610 to 146.995 MHz 147.000 to 147.395 MHz 147.400 to 147.595 MHz 147.600 to 147.995 MHz 148.
Changing the Default Offset Follow these steps to change the default offset for the VFO modes. ! 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3. Press SHIFT. The HTX-242 displays oS and the current offset (in MHz). 4. Rotate TUNE, press UP or DOWN on the microphone, or directly enter the step using the microphone’s keypad to select an offset default (from 0 to 38 MHz). 5. Press SHIFT or PTT to save the setting.
Using the Dual VFOs for Duplex Operation Follow these steps to use one VFO to transmit and the other to receive. 1. Press VFO to select VFO-A. 2. Select a frequency. 3. Press VFO to select VFO-B. 4. Select a frequency. 5. Press DUP. When the HTX-242 displays: VFO-A-T VFO-B it transmits on the VFO-A frequency and receives on the VFO-B frequency. When it displays: VFO-A VFO-B-T it transmits on the VFO-B frequency and receives on the VFO-A frequency.
USING MEMORY CHANNELS The HTX-242 has 40 standard memory channels and one callingfrequency memory, where you can store frequently-used frequencies, along with all settings, for quick access. Storing a Frequency 1. Press VFO and tune to a frequency you want to store. Set all duplex and subaudible tone settings (see “Using Subaudible Tones” on Page 36), the transmit power setting, and the DTMF option. 2. To store the frequency in the calling-frequency memory, press and hold F for at least 1 second.
7. Press ▲. The HTX-242 displays rC and the current receive subaudible tone. 8. Rotate TUNE, or press UP or DOWN on the microphone, to change the receive subaudible tone. 9. Press ▲. The HTX-242 displays tC and the current transmit subaudible tone. 10. Rotate TUNE, or press UP or DOWN on the microphone, to change the transmit subaudible tone. 11. For the calling-frequency memory, press CALL to save all settings. For a standard memory, press ▲. The HTX-242 displays Sn.
Tuning to a Standard Memory Channel 1. Press MR. 2. Rotate M-CH, or press UP or DOWN on the microphone, to select the desired memory channel. Using the Calling-Frequency Memory Press CALL. The HTX-242 recalls all settings saved in the callingfrequency memory. Notes: ! • If you rotate TUNE, press UP or DOWN, or directly enter a frequency, the HTX-242 returns to the last-used VFO. • To return to the mode selected before you used the callingfrequency memory, press CALL again.
Scanning Memory Channels To set the HTX-242 to scan memory channels, press and release MR. Then press and hold MR for at least 1 second. .flashes, and the HTX-242 scans memories that have the scan option turned on (see “Enabling/Disabling Scanning for Memory Channels” on this page). The HTX-242 stops when it encounters a transmission. It resumes scanning according to the saved scan settings (see “Setting the Scan Options” on Page 20). To resume scanning immediately, press MHz.
USING DTMF AND SUBAUDIBLE TONES Your HTX-242 has 10 DTMF (Dual-Tone, Multiple Frequency— another name for touch tones) memories where you can store DTMF sequences. DTMF Memory 0 can hold a 7-digit DTMF paging sequence your HTX-242 must receive for DTMF paging. DTMF Memories 1-10 each hold 15 digits you can quickly transmit. Storing a DTMF Sequence 1. Hold down F for at least 1 second. FUNC flashes. 2. Press DTMF. The HTX-242 displays the sequence stored in the currently selected memory. 3.
Using DTMF Page DTMF page lets other operators page you. To turn on DTMF page, press DTMF so DTMF appears. The HTX-242 does not pass transmissions to the speaker until it receives the sequence you stored in DTMF Memory 0. If DTMF Memory 0 is empty, DTMF page does not operate. When you receive a DTMF page, the HTX-242 turns on the speaker and turns off DTMF page so all transmissions come through.
• Assuming all club members have DTMF page activated, to page everyone, transmit 465ABC. • To page West Side members, transmit 4654ABC. • To page Doug and Cary, transmit 46518ABC. • To page only one person, transmit the 7-digit sequence. Using Auto-Reply If you turn on the auto-reply feature, the HTX-242 automatically sends the sequence stored in the currently-selected DTMF memory when it receives a DTMF page. Follow these steps to turn on auto-reply. 1. Press VFO. 2.
Using DTMF Auto Send If you turn on the DTMF auto-send feature, the HTX-242 automatically sends the sequence stored in the currently-selected DTMF memory every time you press PTT. Follow these steps to turn on auto send. 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR. 4. Repeatedly press ▲ to select the dA option. Then rotate TUNE, or press UP or DOWN on the microphone, to set the option to on. 5. Press MR or PTT to save the setting. 6.
Using Subaudible Tones Some repeaters require you to transmit a subaudible tone to activate them. You can set your HTX-242 to transmit any of the 38 standard subaudible tones. You can also limit incoming reception by setting the HTX-242 to open the squelch only when someone transmits a subaudible tone you select. Valid Subaudible Tones Code XZ XA WA XB WB YZ YA YB ZZ ZA ZB 1Z 1A Freq. (Hz) 67.0 71.9 74.4 77.0 79.7 82.5 85.4 88.5 91.5 94.8 97.4 100.0 103.
5. Press ▲. The HTX-242 displays tC and the currently set transmit tone. 6. Rotate TUNE, or press UP or DOWN on the microphone, to set a different transmit tone. If you do not want a transmit tone, select oFF. 7. Press T-SQL or PTT to save the settings. Activating Subaudible Tone Transmit and Squelch 1. Press T-SQL once. T appears. The HTX-242 includes the selected transmit tone with your transmissions. 2. Press T-SQL again. T-SQL appears.
USING THE MENU Your HTX-242 has a menu that lets you select how some functions work. The previous sections included procedures that access this menu—this section provides an overview. Follow these steps to use the menu: 38 1. Press VFO. 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR. The first menu item appears. Then press to select the desired menu option. 4. Rotate TUNE, or press UP or DOWN on the microphone, to select the setting.
Menu Item SC Sd S1 S2 S3 S4 S5 Lb SL SH Ar Default Option Explanation/Available Settings Scan resume option. ti —time out in 10 seconds. Cr —resume after carrier drops. SE —do not resume scanning. Scan delay (delay before resume when 2.0 SC is set to Cr). 0.5, 1, 2, or 4. –––.––– Scan skip frequency 1 (frequency for HTX-242 to skip when scanning VFO). –––.––– Scan skip frequency 2. ti –––.––– –––.––– –––.––– 4 to oFF bp AS oN on dA oFF 20 21 20 20 Scan skip frequency 3.
TROUBLESHOOTING Error Codes Your HTX-242 has the following three built-in error codes. tF Err —appears if you try to transmit outside the allowed range (see “Extending the Transmit Frequency Range” on Page 16). PLL Err —appears if the HTX-242’s PLL (phase-locked loop) section malfunctions. If turning the HTX-242 off then back on does not correct this error, take it to your local Radio Shack store to arrange for service. EEP Err —appears if the HTX-242’s EEPROM checksum fails.
Replacing the Fuse Your HTX-242 (and vehicle) are protected by a 15-amp fuse in the HTX-242’s positive (red) power wire. If the HTX-242 does not turn on, even when you are sure the power wire is properly connected to a 12V DC power source, check the fuse and replace it, if necessary. 1. Snap open the in-line fuse holder. 2. Remove the fuse from the holder, and slide the fuse out of the end connectors. 3.
SPECIFICATIONS General Frequency Range (Factory) Transmit . . . . . . . . . . . Receive. . . . . . . . . . . . . Frequency Step . . . . . . . . . Frequency Stability . . . . . . Antenna Impedance . . . . . . Speaker . . . . . . . . . . . . . . . Microphone . . . . . . . . . . . . Operating Temperature . . . Dimensions (HWD) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 – 148 MHz . . . . . . . 136.000 – 174.000 MHz . 5/10/12.
Transmitter RF Power Output . . . . . . . . . . . . . . Maximum Deviation . . . . . . . . . . . . Hum and Noise . . . . . . . . . . . . . . . Audio Distortion . . . . . . . . . . . . . . . Audio Response . . . . . . . . . . . . . . . Spurious and Harmonic Emissions Frequency Error . . . . . . . . . . . . . . . Microphone Sensitivity . . . . . . . . . . CTCSS Tone Deviation . . . . . . . . . . DTMF Tone Deviation . . . . . . . . . . . Current Drain . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
SCHEMATICS 44
RF SCHEMATIC 45
DIGITAL SCHEMATIC 46
MICROPHONE SCHEMATIC 47
Radio Shack Limited Warranty This product is warranted against defects for 1 year from date of purchase from Radio Shack company-owned stores and authorized Radio Shack franchisees and dealers. Within this period, we will repair it without charge for parts and labor. Simply bring your Radio Shack sales slip as proof of purchase date to any Radio Shack store. Warranty does not cover transportation costs. Nor does it cover a product subjected to misuse or accidental damage.
