Comtek M-175 Operator's Manual

357 West 2700 South • Salt Lake City, Utah 84115 • Phone: (800) 496-3463 • Fax: (801) 484-6906 • http://www.comtek.com M-175 Personal Communication Transmitter

Printed in the U.S.A. 01-16-12 TABLE OF CONTENTS Introduction ........................................................... Setup ............................................................................... Controls .................................................................. Battery Removal / Replacement ...................................... Battery Charging ...................................................... Auxiliary Audio Input Operation ................................... Snap-On Belt Clip ................................................. Frequency Selection ............................................... Frequency Information .......................................... P-7 Option .............................................................. Optional Accessories ............................................... Trouble Shooting ..................................................... Specifications ......................................................... Warranty and Service .................................................. 1 2 3 4 5 6-7 7 8 9-10 11 12 13-14 15 16

professional quality, compact body-worn transmitter designed for reliable one-way remote communication. It’s ideal for many applications including: personal cueing, assistive listening, tour guide presentations, communication for on-the-job training, (requiring being some distance away or in a noisy environment), and other personal, one-way remote communication situations. For a natural sound, this transmitter incorporates the latest digital and analog technologies to produce high quality sound with low residual noise, wide dynamic range and extended frequency response. The audio processing circuit allows a choice of companded 2:1 audio processing when used with Comtek full fidelity receivers, or non-companded 1:1 audio processing on prescribed channels with Comtek and other lower cost popular receivers. Both audio processing systems have the same frequency response of 80 Hz to 10 KHz. Operating under F.C.C. Regulation Part 90, the M-175 transmitter has greater transmission range and reliability. M-175 Personal Communication Transmitter

the same as the associated COMTEK receiver’s channel. (Channels are indicated by the rotary channel selector switches on the back of the transmitter. See page 8.) b. Open the battery door cover on the transmitter (see page 4) and insert a new nine volt alkaline battery (Eveready E522 or equivalent). This type of battery will offer up to 14 hours of operation. Replace the battery before every use if the demand for fail-safe operation outweighs battery cost. The use of carbon batteries is not recommended. NOTE: If a rechargeable battery is to be used, ensure that it has been allowed to charge at least twelve hours to bring it to full charge (see page 5 for battery charger instructions). c. Connect the microphone to the transmitter by inserting the microphone plug into the receptacle on the top of the transmitter. The transmitter is operating when the transmitter power switch is turned on and the battery status/on indicator illuminates. NOTE: The 48-inch microphone cord also functions as part of the transmitter’s antenna system. For optimum performance, this cord should be fully extended. Coiling or bunching the microphone cord may reduce the range of the transmitter. The transmitter should be carried by the snap-on belt clip (included) or in a pocket or belt-clip pouch. d. In a situation where an extremely loud voice or a very soft voice is used, it is necessary to adjust the audio input gain control while observing the audio “voice” level modulation indicator. A full bright LED indicates full audio compression at 100% modulation. For best performance, the audio input gain should be adjusted for some low level LED luminescence during normal audio levels with occasional full bright peaks indicating 100% modulation. M-175 SETUP Page 2

the transmitter to the desired operating frequency. (See page 9 and 10 for frequency selection chart.) oBATTERY COMPARTMENT: The battery compartment features a hinged battery cover and an alignment system that ensures proper battery polarity. Battery installation and removal is facilitated by simply manipulating the bottom of the battery. p AUXILIARY AUDIO INPUT JACK: Allows transmitter to use line level, earphone level, or fixed AUX as an audio source. q AUDIO “VOICE” MODULATION INDICATOR: This indicator is used in making adjustment with the Audio Input Gain Control. r MIC / ANTENNA JACK: This jack accepts an electret type microphone having a 48” long cord with a micro-mini 2.5 mm mono plug. The microphone cord functions as part of the transmitter’s antenna system and must be in place for auxiliary audio input operation. If microphone function is not necessary, the optional microphone switch should not be on for this operation. s POWER / BATTERY STATUS INDICATOR: This LED indicator will illuminate continuously when the unit is on indicating normal operation. When the battery voltage drops below 6 volts, the LED will flash rapidly, indicating that a new battery is needed. t OPTIONAL MIC SWITCH: This switch turns off the microphone without turning off the transmitter carrier. u AUDIO INPUT GAIN CONTROL: This is a microphone and AUX level input gain control. This control is used with the “Voice” modulation indicator. v ON / OFF SWITCH: This switch turns the transmitter on and off.

The LED on the top of the transmitter indicates the status of the battery as well as indicating that the unit is turned on. When the transmitter is turned on, the LED illuminates. If the battery is low, the green LED will blink rapidly to warn you that the battery will soon be dead. Replace a low battery immediately. M-175 BATTERY REMOVAL / REPLACEMENT Pull back battery door latch and allow battery cover door to spring open. To remove battery, simply manipulate the bottom of battery out of the compartment and remove. To insert battery, face battery with negative terminal in line with large hole in battery compartment, press battery into compartment and close battery door until it snaps shut. Note: It is not possible to put battery in backwards. Battery indicator LED Battery Removal / Replacement

Battery Charging 1. Make sure that a seven cell 9 volt Ni-MH rechargeable battery is used with a minimum of 200 mAh capacity. (Alkaline batteries must not be charged.) 2. Make sure the M-175 is turned OFF. 3. Note that the red charging indicator on the charger is ON when the M-175 is plugged into the charger through the audio output jack. 4. When using the NBC 9-2C charger allow the battery to charge for 14 hours for a full charge. Unit must then be unplugged. When using the NBC 9-3-1 digital fast charger the charger will automatically end the charge cycle and the red LED will change to green. With the NBC 9-3-1 charger the unit may be left in the charger until the unit is used. 5. Periodically open the battery compartment on stored COMTEK units to check for battery leakage. If a battery is leaking, it must be discarded, and the battery compartment must be cleaned or returned to COMTEK’s service department for repairs. IMPORTANT NBC 9-2C 14-hour charger NBC 9-3-1 digital fast charger

Auxiliary Audio Input Operation The M-175 transmitter may transmit from a variety of audio sources such as digital media players, or any audio device having an auxiliary or earphone level audio signal. The auxiliary input cable supplied with the M-175 transmitter (CB-36 ST) will operate with any device having a mini 3.5 mm jack, stereo or mono, and with line level or earphone level output. To accommodate a variety of specialty applications, auxiliary input cables with RCA phono plug, 1/4” audio phone plug, and XLR connectors are available from COMTEK. Setup a. Connect the microphone to the transmitter by inserting the microphone plug into the receptacle on the top of the transmitter. Note: The microphone cord functions as part of the transmitter’s antenna system and must be in place for auxiliary audio input operation. If microphone function is not necessary, the optional microphone switch should not be on for this operation. b. Connect the proper auxiliary input cable to the audio source. Connect the right-angle mini plug end of the auxiliary input cable into the “AUX” input jack of the M-175 transmitter. Note: Check to ensure that the audio source is a line level, earphone level, or fixed AUX level output.

M-175 SNAP-ON BELT CLIP (Included) Belt clip removal c. Turn on the transmitter with program from the audio source being fed to the transmitter. Observe the audio “voice” level modulation indicator. A full bright LED indicates full audio compression at 100% modulation. For best performance, the audio input gain should be adjusted for some low level LED luminescence during normal audio levels with occasional full bright peaks indicating 100% modulation. d. When using the auxiliary audio input with the microphone plugged into the transmitter, priority should be given to the microphone gain adjustment. The mixing balance between the auxiliary audio and the microphone should be made with the volume control of the auxiliary audio source. Note: The optional microphone switch only affects the microphone. It does not affect the auxiliary audio input. M-175 AUX OPERATION (Cont.) / SNAP-ON BELT CLIP STEP 1: Hook belt clip retaining lip over front case ridge. STEP 2: Rotate belt clip down onto case. Apply pressure on both sides of clip, snapping clip retainers into slots. Clip retainer Retainer slot Belt clip removal indent Flex out and pull down with your thumb or a large coin (quarter) to unsnap belt clip from case.

The M-175 transmitter can operate on one of 88 available channels between 72-76 MHz. COMTEK channel designations indicate both standard non-companded channels and high-fidelity companded channels. Channels 1-88 are to be used only with receivers having 2:1 audio companding processing. Channel position 91-00 is to be used only with receivers having linear non-companded audio processing. COMTEK transmitters automatically transmit the proper modulation when set to either number channels 1-88 or channels 91-00 (A-J). After you have determined the channel on which you are going to operate, position the two rotary switches to indicate the channel. The left rotary switch is for tens and the right rotary switch is for ones, e.g. to select channel 41 (72.92 MHz), position the left rotary switch to point to 4 (X10), and position the right rotary switch to point to 1 (X1). Refer to frequency charts on pages 9 and 10 for selectable frequencies. Multiple Channel Operation When multiple transmitters are broadcasting in the same immediate area (within 100 feet), the RF signals will “mix” together generating additional signals. If these product frequencies are too close to a frequency which you are using, you will experience intermodulation interference. This condition is common to all radio receivers to some extent. Simultaneous operation of more than three channels requires frequency coordination to avoid intermodulation interference which could result in poor or unusable performance. To avoid this type of interference, you should select frequencies from one of the standard groups (see group frequency charts on pages 9 and 10), or use COMTEK’s frequency selection software available at www.comtek.com to determine appropriate frequencies or contact COMTEK to obtain a free copy. M-175 FREQUENCY SELECTION

GROUP 1 GROUP 2 GROUP 3 CHAN FREQ 72.02 MHz 72.22 MHz 72.72 MHz 74.61 MHz 75.62 MHz 75.72 MHz 01 11 31 45 70 75 CHAN FREQ 72.08 MHz 72.18 MHz 72.72 MHz 74.77 MHz 75.58 MHz 75.92 MHz 04 09 31 53 69 85 CHAN FREQ 13 25 54 57 81 87 72.26 MHz 72.58 MHz 74.79 MHz 75.25 MHz 75.84 MHz 75.96 MHz Transmitter Proximities For Multiple Channel Operation Frequency groups being transmitted should be separated by 2X the operating area; and for best performance, the group operating areas should have a 100 ft. minimum separation. transmitters Group 2 operating area transmitters transmitters Group 1 operating area Group 3 operating area Transmitter separation Transmitter separation 72-76 MHz STANDARD COMPANDED CHANNELS CHAN FREQ 72.02 MHz 72.04 MHz 72.06 MHz 72.08 MHz 72.10 MHz 72.12 MHz 72.14 MHz 72.16 MHz 72.18 MHz 72.20 MHz 72.22 MHz 72.24 MHz 72.26 MHz 72.28 MHz 72.30 MHz 72.32 MHz 72.34 MHz 72.36 MHz 72.38 MHz 72.40 MHz 72.42 MHz 72.46 MHz 72.50 MHz 72.54 MHz 72.58 MHz 72.62 MHz 72.64 MHz 72.66 MHz 72.68 MHz 72.70 MHz 72.72 MHz 72.74 MHz 72.76 MHz 72.78 MHz 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 CHAN FREQ 72.80 MHz 72.82 MHz 72.84 MHz 72.86 MHz 72.88 MHz 72.90 MHz 72.92 MHz 72.94 MHz 72.96 MHz 72.98 MHz 74.61 MHz 74.63 MHz 74.65 MHz 74.67 MHz 74.69 MHz 74.71 MHz 74.73 MHz 74.75 MHz 74.77 MHz 74.79 MHz 75.21 MHz 75.23 MHz 75.25 MHz 75.27 MHz 75.29 MHz 75.31 MHz 75.33 MHz 75.35 MHz 75.37 MHz 75.39 MHz 75.42MHz 75.46 MHz 75.50 MHz 75.54 MHz 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 CHAN FREQ 75.58 MHz 75.62 MHz 75.64 MHz 75.66 MHz 75.68 MHz 75.70 MHz 75.72 MHz 75.74 MHz 75.76 MHz 75.78 MHz 75.80 MHz 75.82 MHz 75.84 MHz 75.86 MHz 75.88 MHz 75.90 MHz 75.92 MHz 75.94 MHz 75.96 MHz 75.98 MHz 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 Automatic Non-Companded Channels 91 92 93 94 95 96 97 98 99 00 72.1 MHz 72.3 MHz 72.5 MHz 72.7 MHz 72.9 MHz 75.5 MHz 75.7 MHz 75.9 MHz 74.7 MHz 75.3 MHz

E 72.9 MHz H 75.9 MHz J 75.3 MHz GROUP 1 CHANNEL FREQUENCY 92 97 99 B 72.3 MHz G 75.7 MHz I 74.7 MHz CHANNEL FREQUENCY 93 96 C 72.5 MHz F 75.5 MHz GROUP 2 GROUP 3 CHANNEL FREQUENCY 91 92 93 94 95 96 97 98 99 00 A 72.1 MHz B 72.3 MHz C 72.5 MHz D 72.7 MHz E 72.9 MHz F 75.5 MHz G 75.7 MHz H 75.9 MHz I 74.7 MHz J 75.3 MHz Standard Non-Companded Channels (For PR-72b and PR-75) Note: Although the same frequencies appear in the companded and non-companded frequency charts, non-companded channels should not be used with companded receivers. In order to accommodate a greater variety of receivers, the M-175 transmitter incorporates the option to operate with receivers that have companded or non-companded audio processing. However, the M-175 transmitter must operate non-companded with non-companded receivers and companded only with receivers that incorporate companding processing. A mismatch will result in unacceptable audio performance. Basic Companding Theory The dynamic range of the audio signal is compressed in the transmitter at a 2:1 ratio. The receiver then expands the audio signal at a complementary 1:2 ratio to restore the dynamic range of the audio signal to the original level and also to provide additional noise reduction when no audio signal is present. M-175 FREQUENCY INFORMATION (Continued)

The optional MBS-216 mounting-bracket stand is an ideal way to conveniently position the M-175 Option P-7 transmitter for field use. The M-175 clip snaps into the mounting bracket locking the transmitter in place. The MBS-216 maintains a vertical antenna position, maximizing the performance of the M-175 Option P-7 transmitter. MBS-216 mounting bracket stand Included belt clip Auxiliary audio input jack BNC type connector FWA-72TL short top loaded whip antenna M-175 P-7 OPTION Page 11 FWA-72TL Antenna This short, top-loaded, omnidirectional antenna minimizes the size of the antenna required to operate in the VHF frequency range of 72-76 MHz. In order to maintain good propagational efficiency, this type of antenna has limited bandwidth. Two separate antennas must be used to cover the two operating frequency ranges of 72-73 MHz (antenna #1) and 74 to 76 MHz (antenna #2). Both antennas are supplied with the M-175 Option P-7 transmitter. CB-36 XLR (supplied)

2. NBC 9-3-1 Digital fast charger 3. NBC 9-3-12 Digital 12-station fast charger 4. NH9-200 Rechargeable batteries 5. BC-216 Snap-on belt clip (supplied with M-175) 6. P1 Universal pouch 7. SM-185 Unidirectional electret condenser microphone 8. PSC-HM Headworn unidirectional electret microphone Auxiliary Audio Input Cords 9. CB-36 STM Stereo mini 3.5 mm (supplied with M-175) 10. CB-36 RCA Phono plug (optional) 11. CB-36 ST1/4 Stereo 1/4” (optional) 12. CB-36 XLR XLR-F 3 pin connector (optional) M-175 OPTIONAL ACCESSORIES

If... Test indicator lamp doesn’t illuminate when units are turned on... Then... • If rechargeable batteries are used, ensure that they have been allowed to charge at least 14 hours to a full charge. Verify that the charging indicator lamps are illuminated when the charging plugs are plugged into the units. The units’ power switches must be in the “off ” position for charging. • If the test indicator lamp still does not illuminate after a full charge, verify that the system is operational by using a new alkaline battery. If the system is operational with alkaline batteries, the rechargeable batteries or charger may need to be replaced. • The M-175 transmitter must be returned to COMTEK for service if the test indicator lamp does not illuminate when new alkaline batteries are used. Transmitter Audio Problem If... There is no visual indication on the “voice” modulation level indicator when speaking into the microphone of the M-175 transmitter... Then... • Turn up the microphone gain setting clockwise until the voice modulation indicator illuminates with speech level. • Make sure the optional muting switch is in the “mic on” position. • Check the CM-183RT microphone for a broken or frayed microphone cord that may cause intermittent operation. • Test the modulation indicator with the auxiliary audio input using a line level signal and the CB-36ST auxiliary audio input cable to verify normal operation. If the auxiliary audio input activates the voice modulation indicator normally, the CM-183RT microphone may need to be repaired or replaced. • The M-175 transmitter must be returned to COMTEK for service if the auxiliary input test does not activate the voice modulation indicator. M-175 TROUBLE SHOOTING

1. Excessive Distances Operating at distances greater then 200 ft. may cause some intermittent noise. 2. Channel Selection For operation with non-companded receivers (such as PR-75 or PR-72), the M-175 transmitter must be set to one of 10 non-companded channels 91-00. For high-fidelity operation, the companded channels 1-88 must be used with companded receiver PR-216/72MHz model. (See page 9 for Frequency Information.) 3. Gain Problem Check the microphone gain setting on the M-175 transmitter for normal operation with the “voice” modulation indicator (See page 2 section d.) Low modulation will render poor signal-to-noise ratio. 4. Channel Interference Monitor the receiver with the headphone plugged in and with the transmitter turned “OFF” on the channel that the transmitter is tuned to. If interference noise is heard, a new clear channel must be selected. 5. Transmitter Power and Receiver Sensitivity Check the M-175 transmitter with the PR-75 or PR-216/72MHz receiver for normal R.F. sensitivity. This can easily be done by range checking the receiver and transmitter with the microphone cord antenna removed from the transmitter. Tune the receiver and transmitter to a clear channel and place the transmitter on a non-metallic table. Remove the microphone cord antenna from the transmitter, and turn on the transmitter. Plug the headphone cord into the receiver, and turn the receiver on. Then walk away from the transmitter while listening for noise build-up just before the squelch action takes place. A distance of 10 to 15 feet should be obtained with the PR-75 or PR-72 and 20 to 30 feet with the PR-216/72MHz receiver. If the receiver and transmitter do not pass this test, both receiver and transmitter must be returned to COMTEK for service. M-175 TROUBLE SHOOTING (Continued)

type microphone - 3000 ohm • Aux/Line input impedance - 10 k ohm at 0 dBV nominal Connectors: Microphone - Micro-mini mono 2.5 mm Auxiliary - Mini stereo 3.5 mm Audio: Tip and sleeve Battery Charging: Tip and sleeve Controls and Indicators: • Synthesized channel selection switches • Power On/Off switch • Optional microphone switch • Audio input gain control • Power/Battery status indicator • Audio (voice level) modulation indicator • Manual/Automatic compand switch Frequency Response: 80 Hz to 10 kHz Audio Distortion: Less than 1% at 80% modulation Modulation Limiter: Soft compressor with 30 dB linear overload protection; attack time - less than 1 ms, recovery time - 10 ms Frequency Modulation: 10 kHz deviation companded Operating Radio Frequency: ity: 88 synthesized channels in the 72-76 MHz band. Out-of-Band Emissions: Better than 50 dB below carrier R.F. Stability: 20 ppm XTL controlled Digitally synthesized RF Power Output: 40 mW to antenna system FCC Compliance: Type Accepted under FCC Part 90 Antenna System: Body-worn microphone cord. Current Drain: 35 mA average current Battery: • 9 volt alkaline Eveready 522 or equivalent for up to 14 hours of use • Rechargeable 9 volt Ni-MH 200 mAh battery for up to 7 hours of operation • Rechargeable 9 volt Lithium Polymer 500 mAh battery for up to 14 hours of use Dimensions: 1 1/16" x 2 1/4" x 3 1/2" (27 mm x 57 mm x 89 mm) Weight: 5 ounces (140 grams) NOTE: Specifications subject to change without notice or obligation

Warranty COMTEK transmitters and receivers are warranted to be free from defects in workmanship and material under normal stand-alone use and conditions for a period of two years from date of original purchase. Items such as headphones, earphones, neckloops, and cords are warranted to be free from defects in workmanship and material for a period of 90 days from the date of original purchase. Batteries are not covered by this warranty. Damage due to abnormal use, extreme conditions, misuse, use of the product as a component of another product, ill treatment and unauthorized modification and repairs are not covered by this warranty. COMTEK is not liable for any consequential or punitive damages arising out of any failure of the equipment to perform as intended. COMTEK shall bear no responsibility or obligation with respect to the manner of use of any equipment sold by it. COMTEK SPECIFICALLY DISCLAIMS AND NEGATES ANY WARRANTY OF MERCHANTABILITY OR FITNESS OF THE PRODUCT FOR A PARTICULAR PURPOSE INCLUDING, WITHOUT LIMITATION, ANY WARRANTY THAT THE USE OF SUCH EQUIPMENT FOR ANY PURPOSE WILL COMPLY WITH APPLICABLE LAWS AND REGULATIONS. Service Policy Warranty repairs must be done by COMTEK. Only factory technicians are authorized to perform warranty service on the M-175 receiver. Before returning the M-175 for service, a Return Authorization Number should be obtained from the service department by calling 1-800-496-3463 or 1-801-466-3463. Return the unit to the factory with the original or comparable packing. COMTEK will pay for insurance and ground return shipping costs in the United States for all warranty service. 357 West 2700 South • Salt Lake City, Utah 84115 • Phone: (800) 496-3463 • Fax: (801) 484-6906 • www.comtek.com E-mail: [email protected]