DR175
COMPACT RECEIVER
OPERATING INSTRUCTIONS
and trouble-shooting guide
Digital Code Squelch
LECTROSONICS, INC.
Rio Rancho, NM
INTRODUCTION
Thank you for selecting the Lectrosonics system.
The DR175 represents over 70 years of combined experience in the design of RF
and audio devices and sets new standards for RF performance and flexibility. This
receiver utilizes a “maximal ratio combining” technique, providing a very effective
type of diversity reception. This is the first high performance receiver on the market
to utilize this technique to combine the outputs of two separate receivers without
hard-switching. The result is seamless audio reproduction without dropouts and
superb, noise-free operation, even in weak overall signal conditions.
This is a “true diversity” receiver in the purest sense. The audio outputs of two
separate receivers are mixed via a non-switching circuit that blends the two audio
signals together in an optimum ratio. The ratio of this mixture is controlled by a circuit
that monitors the comparative signal to noise ratios in both receivers and then “pans”
back and forth to regulate the mixture. The receiver with the least high frequency
noise is favored in the resultant blend.
The DR175 receiver was designed for professional users who demand outstanding
performance and flexibility. It is compatible with all Lectrosonics high band transmitters.
TABLE OF CONTENTS
INTRODUCTION .................................................................................................. 2
FRONT PANEL CONTROLS AND FUNCTIONS ................................................ 3
REAR PANEL CONTROLS AND FUNCTIONS .................................................. 3
ANTENNA USE AND PLACEMENT ................................................................... 4
OPERATING INSTRUCTIONS ............................................................................ 5
INDICATOR QUICK REFERENCE ...................................................................... 5
TROUBLESHOOTING ......................................................................................... 6
DR175 REPLACEMENT PARTS and ACCESSORIES ...................................... 6
SPECIFICATIONS AND FEATURES ................................................................... 7
SERVICE AND REPAIR ....................................................................................... 8
RETURNING UNITS FOR REPAIR ..................................................................... 8
WARRANTY ......................................................................................... Back cover
2
Ratio Diversity Receiver
FRONT PANEL CONTROLS AND FUNCTIONS
MODULATION INDICATORS Two (2) LEDs indicate the audio level (modulation) of the incoming signal, which are
typically used for proper adjustment of the transmitter’s “MIC LEVEL” or “GAIN”. The -20 LED (green) lights during
normal modulation. The 0dB (red) LED indicates maximum modulation and that the transmitter audio input may be
“limiting.” Occasional flickering of this LED is normal. It should not stay on for long periods, however.
OFF/ON This switch turns the receiver power off and on.
CODE Lights when the transmitter is turned on and the internal code in the transmitter matches this particular
receiver. If the receiver is turned on after the transmitter, the code led will not come on. In this case, it will be necessary to turn the transmitter off and back on to enable the receiver. When the carrier signal from the transmitter is too
weak to produce a clean audio signal the receiver will squelch (no audio) but the code lamp will remain lit.
OPTI-BLEND LEDs The audio outputs of two separate receivers are mixed together in a “ratio” that is regulated by
comparing the signal to noise ratios in the two receivers. The mixture ratio of the two audio signals is indicated on the
front panel by two LEDs that vary in brightness. As a build-up of noise occurs in one receiver, the corresponding LED
for that receiver dims or goes out as the circuitry pans to the other receiver. Since the mixture ratio of the two audio
signals is determined by a comparison of their signal to noise ratios, the “blending” action occurs regardless of how
strong (or weak) the incoming RF signals are. This is the distinct advantage of this receiver design over any other
type of diversity system available.
AUDIO LEVEL This control knob adjusts the audio level of the XLR output on the rear panel.
GRN
RATIO
DIVERSITY
MODULATION
–20
0dB CODE
GRN RED
A B
AUDIO LEVEL
GRN
OPTI-BLEND
LECTROSONICS
OFF
ON
POWER
RED
DIGITAL
CODE
YEL
REAR PANEL CONTROLS AND FUNCTIONS
ANTENNA INPUTS These inputs connect to any 50 ohm antenna with a BNC type connector.
12 VDC IN This input connects to the supplied CH-12 AC adapter for powering the receiver from a 110/120V AC
source. The receiver may also be powered from external 12 volt DC sources using the correct plug (Switchcraft S760 power plug). The center pin is positive. (+).
AUDIO OUT This XLR type connector supplies a balanced, low impedance output at microphone level. The audio
signal is present on pins 2 and 3, while pin 1 is ground. The output level of this jack is controlled by the AUDIO
LEVEL control on the front panel of the receiver. Pin 2 is “hot” in terms of polarity.
ANT B ANT A
1
AUDIO OUT
Rio Rancho, NM – USA
2
3
12V DC IN
3
ANTENNA USE AND PLACEMENT
There are two antennas included with this receiver. The A170 AC is a whip antenna that connects to either terminal
on the rear panel of the DR175 receiver.
Position the antennas so that they are not within 3 or 4 feet of large metal surfaces. If this is not possible, try to
position the antennas so that they are as far away from the metal surface as is practical. It is also good to position the
receiver so that there is a direct “line of sight” between the transmitter and the receiver antenna. In situations where
the operating range is less than about 50 feet, the antenna positioning is much less critical.
A wireless transmitter sends a radio signal out in all directions. This signal will often bounce off nearby walls, ceilings,
etc. and a strong reflection can arrive at the receiver antenna along with the direct signal. If the direct and reflected
signals are out of phase with each other a cancellation may occur. The result would be a “drop-out.” A drop-out
sounds like either audible noise (hiss), or in severe cases, may result in a complete loss of the carrier and the sound
when the transmitter is positioned in certain locations in the room. A drop-out normally sounds like “hum” or “hiss.”
Moving the transmitter even a few inches will change the sound of the hum or hiss, or eliminate it. A drop-out situation may be either better or worse as the crowd fills and/or leaves the room, or when the transmitter or receiver is
operated in a different location.
The DR175 receiver offers a sophisticated diversity design which overcomes drop-out problems in almost any imaginable situation. In the event, however, that you do encounter a dropout problem, first try moving the antenna at least 3
or 4 feet from where it was. This may alleviate the drop-out problem on that antenna. If drop-outs are still a problem,
try moving the antenna to an entirely different location in the room or moving the antennas in closer to the transmitter
location. By observing the OPTI-BLEND LEDs on the front panel, you can determine which antenna is suffering
weak signals.
Lectrosonics transmitters radiate power very efficiently, and the receivers are very sensitive. This reduces drop-outs
to an insignificant level. If, however, you do encounter drop-outs frequently, call the factory or consult your dealer.
There is probably a simple solution.
RANSMITTER
PHASE
CANCELLATION
REFLECTIVE SURFACE
INDIRECT SIGNAL
DIRECT SIGNAL
LECTROSONICS
DIRECT SIGNAL
RECEIVER
INDIRECT SIGNAL
MULTI-PATH DROPOUT
4
Ratio Diversity Receiver
OPERATING INSTRUCTIONS
1) Connect the power supply.
2) Attach and place the antennas.
3) Connect the audio cable.
4) Set the front panel AUDIO LEVEL control fully counter-clockwise and set the POWER switch to ON. Check to
see that the red POWER LED lights up.
5) Adjust the transmitter “gain”. THIS IS PERHAPS THE MOST IMPORTANT STEP IN THE SET UP PROCEDURE.
See your transmitter manual (Operating Instructions section) for specific directions on the proper gain adjustment
of your particular transmitter.
6) After adjusting the transmitter gain, set the AUDIO LEVEL to a comfortable listening position.
7) Operate the system and adjust the receiver output level as required for your equipment. The input levels on
different VCR’s and PA equipment vary, which may require that you set the OUTPUT ATTENUATOR control in an
intermediate position. Try different settings and listen to the results. If the output of the receiver is too high, you
may hear distortion or a loss of the natural dynamics of the audio signal. If the output is too low, you may hear
steady noise (hiss) along with the audio.
INDICATOR QUICK REFERENCE
CODE LED - Lights when the transmitter is turned on and the internal code in the transmitter matches this particular
receiver. If the receiver is turned on after the transmitter, the code led will not come on. In this case, it will be necessary to turn the transmitter off and back on to enable the receiver. When the carrier signal from the transmitter is too
weak to produce a clean audio signal the receiver will squelch (no audio) but the code lamp will remain lit.
POWER - This red LED lights up when the receiver is properly connected to a power supply and switched on.
MODULATION -- The audio level is indicated by these two LEDs, -20 and 0dB. The normal operating level occurs
when the -20 (green) LED is lighting up with the audio. The 0dB LED (red) lights up when the audio level is high and
the signal is being compressed in the transmitter. An extremely high audio level may cause distortion. If neither LED
lights up when audio is being produced through the system, the audio level is too low, which may produce audible
background noise (hiss) in the audio. The audio level is adjusted with the transmitter GAIN or MIC LEVEL control.
OPTI-BLEND LEDs -- These green LEDs indicate the blending action of the panning circuit in response to the
comparison of signal to noise ratios in the two receivers. The audio from either receiver is being mixed into the blend
when the corresponding LED lights up. The brightness of these LEDs varies in proportion to the amount of audio
being utilized from the associated receiver.
Rio Rancho, NM – USA
5
TROUBLESHOOTING
Before going through the following chart, be sure that you have a good battery in the transmitter and that the transmitter power LED is indicating normally.
SYMPTOM POSSIBLE CAUSE
NO POWER LED 1) Receiver switch in “OFF” position
2) External 12 Volt power disconnected
3) CH-12 AC adapter disconnected
NO CODE LED 1) Transmitter not turned on
2) Transmitter battery dead
3) No microphone on transmitter
4) Receiver antenna not connected
CODE LED ON BUT NO SOUND
AND NO MODULATION LEDS
MODULATION LED’s ON 1) Receiver LEVEL control turned down
BUT NO SOUND 2) Audio cable disconnected
1) Transmitter switch in “MUTE” position
2) Transmitter microphone not connected
3) Possible malfunction in the audio section of the
transmitter (See transmitter manual)
4) Check transmitter modulation LEDs for possible
transmitter problem
3) Recorder or sound system off, or not properly adjusted
DR175 REPLACEMENT PARTS and ACCESSORIES
Part No. Description
CH-12 110 Volt AC adapter for DR175 receiver.
A-170 AC 1/4 wave whip on a right angle BNC connector.
A-185 Coax Remote, folded-dipole antenna with coaxial cable.
A-185-BNC Telescoping 1/4 wave whip on a swiveling BNC connector.
A-200 Remote dipole antenna with aluminum mounting block;
supplied with one built-in telescoping whip and one
detachable telescoping whip.
6
Ratio Diversity Receiver
SPECIFICATIONS AND FEATURES
Operating frequencies: 150 to 216MHz, crystal controlled
Sensitivity: -110dBm for 20dB Sinad (0.7uV)
Signal/noise ratio: 96dB flat; 99dB A-weighted
Squelch quieting: Greater than 109dB
AM rejection: Below the noise at all input levels
Modulation acceptance: Greater than ±15kHz
IF Selectivity: 150kHz interference bandwidth; -30dB @ ±200kHz
Third order intercept: +5dBm
Diversity technique: Dual receiver “opti-blend” audio combining
Audio outputs: XLR: 200 Ohm bal.; 100mV max.
Antenna inputs: Dual BNC female; 50 Ohm impedance
Controls: Front panel attenuator controls balanced outputs; Power switch
Indicators: Red LED for power “ON”; Dual modulation LEDs show
transmitter audio level; Dual “opti-blend” LEDs display mixture
ratio; Code ON LED
Power requirements: 12V DC (rear panel jack); 110V AC (using supplied CH-12
AC adapter)
Power consumption: 170mA max
Weight: 10.1 ozs
Dimensions: 3¼” wide, 1¼” high, 5¼” deep
Specifications subject to change without notice
Rio Rancho, NM – USA
7
SERVICE AND REPAIR
If your system malfunctions, you should attempt to correct or isolate the trouble before concluding that the equipment
needs repair. Make sure you have followed the setup procedure and operating instructions. Check out the interconnecting cords and then go through the TROUBLE SHOOTING section in the manual
We strongly recommend that you do not try to repair the equipment yourself and do not have the local repair shop
attempt anything other than the simplest repair. If the repair is more complicated than a broken wire or loose connection, send the unit to the factory for repair and service. Don’t attempt to adjust any controls inside the units. Once set
at the factory, the various controls and trimmers do not drift with age or vibration and never require readjustment.
There are no adjustments inside that will make a malfunctioning unit start working.
LECTROSONICS service department is equipped and staffed to quickly repair your equipment. In-warranty repairs
are made at no charge in accordance with the terms of the warranty. Out of warranty repairs are charged at a modest
flat rate plus parts and shipping. Since it takes almost as much time and effort to determine what is wrong as it does
to make the repair, there is a charge for an exact quotation. We will be happy to quote approximate charges by phone
for out of warranty repairs.
RETURNING UNITS FOR REPAIR
You will save yourself time and trouble if you will follow the steps below:
A. DO NOT return equipment to the factory for repair without first contacting us by letter or by phone. We need to
know the nature of the problem, the model number and the serial number of the equipment. We also need a phone
number where you can be reached 8 am to 4 pm (Mountain Standard Time).
B. After receiving your request, we will issue you a return authorization number (R.A.). This number will help speed
your repair through our receiving and repair departments. The return authorization number must be clearly shown on
the outside of the shipping container.
C. Pack the equipment carefully and ship to us, shipping costs prepaid. If necessary, we can provide you with the
proper packing materials. UPS is usually the best way to ship the units. Heavy units should be “double-boxed” for
safe transport.
D. We also strongly recommend that you insure the equipment, since we cannot be responsible for loss of or damage
to equipment that you ship. Of course, we insure the equipment when we ship it back to you.
Mailing address:
Lectrosonics, Inc.
PO Box 15900
Rio Rancho, NM 87174
USA
Shipping address:
Lectrosonics, Inc.
581 Laser Rd.
Rio Rancho, NM 87124
USA
Telephones:
Regular: (505) 892-4501
Toll Free (800) 821-1121
FAX: (505) 892-6243
World Wide Web: http://www.lectrosonics.com Email: sales@lectrosonics.com
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Ratio Diversity Receiver
Rio Rancho, NM – USA
9
LIMITED ONE YEAR WARRANTY
LIMITED ONE YEAR WARRANTY
The equipment is warranted for one year from date of purchase against defects in
materials or workmanship provided it was purchased from an authorized dealer. This
warranty does not cover equipment which has been abused or damaged by careless
handling or shipping. This warranty does not apply to used or demonstrator equipment.
Should any defect develop, Lectrosonics, Inc. will, at our option, repair or replace any
defective parts without charge for either parts or labor. If Lectrosonics, Inc. cannot
correct the defect in your equipment, it will be replaced at no charge with a similar new
item. Lectrosonics, Inc. will pay for the cost of returning your equipment to you.
This warranty applies only to items returned to Lectrosonics, Inc. or an authorized
dealer, shipping costs prepaid, within one year from the date of purchase.
This Limited Warranty is governed by the laws of the State of New Mexico. It states the
entire liablility of Lectrosonics Inc. and the entire remedy of the purchaser for any
breach of warranty as outlined above. NEITHER LECTROSONICS, INC. NOR
ANYONE INVOLVED IN THE PRODUCTION OR DELIVERY OF THE EQUIPMENT
SHALL BE LIABLE FOR ANY INDIRECT, SPECIAL, PUNITIVE, CONSEQUENTIAL,
OR INCIDENTAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE
THIS EQUIPMENT EVEN IF LECTROSONICS, INC. HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES. IN NO EVENT SHALL THE LIABILITY OF
LECTROSONICS, INC. EXCEED THE PURCHASE PRICE OF ANY DEFECTIVE
EQUIPMENT.
This warranty gives you specific legal rights. You may have additional legal rights which
vary from state to state.
LECTROSONICS, INC.
581 LASER ROAD
RIO RANCHO, NM 87124 USA
November 1, 2001
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