Page 2 - FEATURES; INTRODUCTION
2 Your HTX-242 Two-Meter Mobile Transceiver is an exciting addi-tion 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...
Page 3 - Using this Manual
3 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...
Page 4 - CONTENTS
4 CONTENTS Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 Unpacking the Transceiver . . . . . . . . . . . . . . . . . . . . . . . . . 6Connecting the Microphone . . . . . . . . . . . . . . . . . . . . . . . . . 6 Mounting the HTX-242 in a Vehicle . . . . . ....
Page 6 - INSTALLATION; Unpacking the Transceiver
6 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 trans-c...
Page 7 - Mounting the HTX-242 in a Vehicle
7 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 Use the supplied ...
Page 8 - Connecting an Antenna
8 Connecting an Antenna You can connect a variety of antennas for both mobile and base-station 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 loca-tion...
Page 9 - Connecting to your Vehicle’s Power
9 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. Co...
Page 10 - Using the HTX-242 as a Base Station
10 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 • 5...
Page 11 - Using the HTX-242 with Packet Radio; Connecting an External Speaker (Optional)
11 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 HTX- 242’s MIC jack at your local Radio Shack store (Cat. No. 279-440). Connecting an External Speaker (Opti...
Page 12 - UNDERSTANDING THE HTX-242; Dual VFO Modes
12 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 fea-tures. Dual VFO Modes The VFO (Variable-Frequency Oscillator) modes let you directly select a frequency anywhere within the HTX-242’s operat...
Page 13 - Repeater Operation; Memor y Channels
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 interfer-ence from other nearby radio transmitters. When a repeater uses a subaudible ...
Page 14 - Understanding the Display; BUSY
14 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-TVFO-B — appears when you select the DUP-A mode (transmit on VFO-A and receive on V...
Page 15 - DTMF
15 + 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 tran...
Page 16 - BASIC OPERATION; Resetting the HTX-242; PLL Err; Extending the Transmit Frequency Range
16 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 P...
Page 17 - LOW; Locking the Controls; LOCK
17 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 h...
Page 18 - Selecting a Frequency; Directly Entering a Frequency
18 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 . Tuning to a Fr...
Page 19 - Scanning for a Frequency; Setting the Frequency Step; St
19 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. Setting the Frequency Step The factory default frequency step is 20 kHz. Each time you rotate TUNE one click, or press UP or DOWN on the microphone, the fre- quency chan...
Page 20 - Setting the Scan Options; Storing Scan Skip Frequencies
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 ....
Page 21 - Setting the Scan Resume Delay; cr; Setting the Scanning Range; FUNC
21 Setting the Scan Resume Delay When you set the scan resume condition to cr (carrier), the HTX- 242 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...
Page 22 - Receiving Transmissions; Transmitting; HIGH; tF Err
22 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 b...
Page 24 - Limiting Transmit Duration; Turning the Keytone Beep On and Off
24 Limiting Transmit Duration When you communicate on the 2-meter band, you should keep your transmissions as brief as possible. Most repeaters have built-in 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 tra...
Page 25 - ADVANCED OPERATION; Frequency Offset Defaults; Turning Auto Duplex On and Off
25 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: The default offset is 600 kHz. For example, if you tune to receive 146.940 MHz, the HTX-242 automatically transmits at 146.340 MHz (600 kH...
Page 26 - Changing the Default Offset; Reversing the Offset
26 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 e...
Page 27 - Using the Dual VFOs for Duplex Operation
27 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-TVFO-B it transmits on the V...
Page 28 - USING MEMOR Y CHANNELS; Storing a Frequency; Changing Stored Settings; rF
28 USING MEMOR Y CHANNELS The HTX-242 has 40 standard memory channels and one calling-frequency memory, where you can store frequently-used frequen-cies, 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 subaudib...
Page 29 - Sn
29 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 ...
Page 31 - Enabling/Disabling Scanning for Memor y Channels
31 Scanning Memor y 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-24...
Page 32 - USING DTMF AND SUBAUDIBLE TONES; Storing a DTMF Sequence; Transmitting a DTMF Sequence
32 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 di...
Page 33 - Using DTMF Page; Using Group Calling
33 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 trans- missions 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...
Page 34 - on
34 • 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...
Page 35 - Using DTMF Auto Send
35 Using DTMF Auto Send If you turn on the DTMF auto-send feature, the HTX-242 automat-ically sends the sequence stored in the currently-selected DTMF memory every time you press P TT. Follow these steps to turn on auto send. 1. Press VFO . 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR ...
Page 36 - Using Subaudible Tones; Valid Subaudible Tones; oFF
36 Using Subaudible Tones Some repeaters require you to transmit a subaudible tone to acti-vate 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 subaudibl...
Page 37 - tC; Activating Subaudible Tone Transmit and Squelch; Setting the DTMF Page and Subaudible Tone Alert; ALT; ALT
37 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 P TT to save the settings. Activating Subaudible Tone Transmit and...
Page 38 - USING THE MENU
38 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: 1. Press VFO . 2. Hold F for at least 1 second. FUNC flashes. 3. Press MR ....
Page 40 - TROUBLESHOOTING; Error Codes
40 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) sec- tion malfunctions. If...
Page 41 - Replacing the Fuse
41 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...
Page 42 - SPECIFICATIONS; General; Receiver
42 SPECIFICATIONS General Frequency Range (Factory) Transmit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 144 – 148 MHz Receive. . . . . . . . . . . . . . . . . . . . . . . . 136.000 – 174.000 MHz Frequency Step . . . . . . . . . . . . . . 5/10/12.5/20/25/50/100 kHz Frequency Stability ...
Page 43 - Transmitter
43 Transmitter RF Power Output . . . . . . . . . . . . . . . . . . . 45 W (high)/10 W (Low) Maximum Deviation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 kHz Hum and Noise . . . . . . . . . . . . . . . . . . . . . . . . Better than 35 dBAudio Distortion . . . . . . . . . . . . . ...
Page 44 - SCHEMATICS
Page 45 - RF SCHEMATIC
Page 46 - DIGITAL SCHEMATIC
Page 47 - MICROPHONE SCHEMATIC