Cadco DC2000 User manual

B R O A D B A N D E Q U I P M E N T
Operating Manual
for the
DC2000 Digital Agile Down
Converter
2363 Merritt Drive Garland, Texas 75041
Phone [phone] FAX [phone]

2
Table of Contents
Important Notices 3
Suggestions for Headend Racking and Maintenance 5
Forward: Features and Options 6
Setup & Operating Instructions: DC2000 7
Setup & Operating Instructions: Dual RS232 Option 13
Panel Views, Front and Rear 18
Questions, Problems, etc. 19
Problem Troubleshooting Guide 20

3
Important Notices
Shipping Loss or Damage
Before signing the Common Carrier’s delivery receipt, count the number of cartons and
inspect each for visible damage. If the number of cartons does not agree with the receipt or
there is damage, make note of these discrepancies on all copies of the receipt before signing.
Immediately unpack the equipment and inspect for concealed damage. If damage is found,
notify the carrier immediately. We suggest you keep the shipping carton and packaging
material should the equipment ever need to be returned.
After filing you claim, notify CADCO for assistance on repair or replacement disposition.
CAUTION - Unauthorized Repair
Unauthorized repair, modification or disassembly during the warranty period may cancel the
warranty. Should field repairs or modifications be desired, CADCO technicians may be able
to provide helpful suggestions, saving you both time and money.
Notice of Proprietary Data and Changes
Data, drawings, designs represented and all other material contained herein are the
proprietary property of CADCO Systems, Inc., and may not be reproduced or duplicated in
any form without written authorization by CADCO Systems, Inc. All material is subject to
change without notice or obligation.
Equipment Return
Should you desire to return the equipment for service, please call CADCO prior to
shipping. Enclosing as much information as possible on the reason for return and the
work desired will expedite service and help to insure your satisfaction. If possible, pack
the equipment in the original carton and materials. If the original packaging material is
no longer available, pack the equipment in cushioning material sufficient to provide a
minimum of 1.5 inches separation between the carton and the equipment. No Return
Authorization number is required. Include your return address, telephone number and
method of return shipment. Ship the equipment prepaid to the address in this manual.

4
Reasons for using CADCO Factory Service:
CADCO services exclusively CADCO equipment
Designed and manufactured your CADCO equipment
Knows CADCO equipment better than any other service provider
Technicians are trained on all CURRENT and PAST technical product
information
Technicians use specialized testing and alignment tools designed for
CADCO equipment
Technicians may often help with a specialized application
Toll-free factory sales and service hotline
Factory service rates are very competitive and in many cases less
expensive than non-factory service stations
Guarantees factory service for two years
Is known for fast, friendly customer service

5
Suggestions for Headend Racking and Maintenance
For prolonged equipment life and operating stability, CADCO makes the following
recommendations:
All headends should be installed in an environmentally controlled dust-free room
having a nominal temperature of 80 F (26 C) and 60% humidity. The room
should be protected from rodents and insect pests.
All equipment should be mounted in standard equipment racks or cabinets
All equipment should be rack spaced at one panel height, 1.75 inches (4.44cm).
There should be nothing between the equipment preventing air circulation.
Please make certain headend wiring and current capacity has adequate safety
margins. Never cascade AC powering strips. Use separate outlets. If AC power
is subject to fluctuation we recommend a constant voltage transformer be used.
Beware of ground loops and be certain all wiring is bonded and properly
grounded. Consult a codebook as needed.
All equipment racks should be electrically bonded together and earth grounded
All equipment interconnecting RF cables should be a minimum of double
shielded and quad shielded is recommended. Poorly shielded cable causes cross-
modulation picture degradation between equipment.
Always use the coax connector intended for the coaxial cable used. Be certain it
is installed as recommended by the manufacturer. Connectors should be RFI
shielded.
RF Input and RF Output cables should be on opposite sides of the equipment
rack. Never bundle input and output RF cables together.
Operate each up-converter at the RF output level recommended. If it is
necessary to reduce the RF Output level, always operate the equipment as
recommended and reduce the RF
Equipment RF test points are only relative indicators of the actual RF output
level. All RF operating level measurements should be made at the RF Output of
each unit.
When the headend is initially placed in service, create a record of all operating
parameters for each channel’s equipment. Referring to these records during
routine maintenance provides a helpful record of operating changes.

6
FORWARD
INTRODUCTION
CADCO Systems thanks you for purchasing the Model DC2000 Digital Agile Low Noise
down converter. The DC2000 contains the latest in CATV electronics, including
synthesized crystal-referenced phase-locked-loop oscillators, microprocessor control,
hybrid amplifiers and saw-filtered output. In addition to these features, the DC2000 has
Frequency Input with 25 KHz frequency tuning allowing for more accurate tuning then
channel-by-channel tuning. This gives better flexibility and will work with all Cable
standard and HRC systems.
FEATURES
Digital Tuner for Digital and Analog Input Signals
Totally Microprocessor Controlled with Self-Diagnostic Monitoring
Selectable Input Frequency
Frequency: 7MHz through 756 MHz
SAW-filtered Output Centered on 44MHz
Defeatable Automatic Gain Control (AGC) for Manual Gain Control (MGC)
+40dBm Digital Signal / +37dBm Analog Signal Output Using Low-Distortion Hybrid
Amplifiers
Non-volatile Channel Memory
Synthesized Oscillators
Crystal Referenced
Phase Locked
Digital LED Readout
Surface Mount Technology (SMT) Construction
RF Muted During Tuning
AVAILABLE OPTIONS
Dual RS232 Control for Daisy Chain Capability

7
General Setup and Operating Instructions
CADCO DC2000 Digital Agile Down Converter
NOTE: Power measurements for digital signals referenced throughout this manual refer to
envelope power , and are better measured with a power meter than with a spectrum
analyzer.
Position the CADCO DC2000 Digital Agile Down Converter in its installation mount or
rack
Locate the antenna lead or cable drop that will provide the input signal for the DC2000
Agile Down Converter.
Ensure that the input signal provides an adequate signal. The recommended input level for
best performance from the CADCO DC2000 Agile Down Converter without optional pre-
amplifier is from 0dBmV to +10dBmV, with optional pre-amplifier is from –10dBmV to
0dBmV.
Connect the input-source cable drop or antenna lead to the F-connector on the rear panel of
the DC2000 marked “RF INPUT”.
Connect the output of the DC2000 to a 75 load, normally a channel combiner, via an RF
cable connected to the F-connector marked “IF OUTPUT” on the rear panel of the
DC2000.
Connect the CADCO DC2000 to a proper AC electrical source. The correct electrical input
type for the unit is marked on the rear panel, directly under the entrance of the power cord
into the unit.
NOTE: CADCO power supplies are designed so that, under certain power line or
heat buildup conditions, the unit shuts off. An indication is no RF output, although
the POWER LED on the front panel remains illuminated. If this occurs, unplug the
power cord and wait at least two (2) minutes before reapplying power. Upon
reapplying power, you should again have RF output. If the unit fails to provide RF
output again, or should the unit return to shutdown mode, telephone your distributor
for assistance or call CADCO Systems direct at 800-877-2288. Remember: CADCO
recommends a 1.75” air circulation space between each piece of rack-mounted
equipment.

8
Input Channel Selection
Select the desired input frequency using the front panel controls. If the units input frequency
is a Channel it should be tuned to the Center Frequency of the desired Channel. Example:
Channel 3 is input as 63.000 instead of 61.250. See Appendix for Channel Tuning Charts.
NOTE: The CADCO DC2000 Agile Down Converter has a built-in delay in the input frequency
tuning circuits. In order to change frequency, hold the input select switch in the up- or down-position for at least
three seconds
When the circuit is defeated, frequency selection will proceed normally. Frequency display
will start moving higher in frequency when front panel selector switch is raised and
frequency will start moving lower when front panel selector switch is lowered. Each flip of
the switch will move the frequency 25kHz. Holding switch in either position will keep the
display moving up or down frequency and the rate of frequency change will increase until
the 1 MHz Display LED is changing at a rapid rate. Once frequency is selected and select
switch is released for 5 seconds the 3 second delay circuit reactivates.
NOTE: The FREQUENCY LOCK LED on the front panel display may also
blink during input-frequency tuning.
Connect a Spectrum Analyzer (recommended) or a Field Strength Meter to the F-connector
marked “IF OUTPUT” on the rear panel of the DC2000 Agile Down Converter. If the unit
is already connected to another device, disconnect that device from the unit.
To use the DC2000 in AGC (Automatic Gain Control) configuration, ensure that the rear
panel AGC/MGC switch is in the AGC position. To use the DC2000 in MGC (Manual
Gain Control) configuration, ensure that the rear panel AGC/MGC switch is in the MGC
position.
MGC Operation
Using the front panel control marked “MANUAL GAIN,” adjust the IF output of the unit.
The recommended output level is +25dBmV as measured at 44 MHz of the haystack.

9
MGC Setup And Operation
If you are using the DC2000 for DOCSIS (cable modem). Return path operation uses it
should be operated in Manual Gain Control (MGC) only. Manual Gain Control is needed to
keep the DOCSIS (cable modem) from chasing the Automatic Gain Control (AGC).
If you are using the DC2000 for off-air or other antenna receive applications the MGC may
cause you to experience fluctuations in the output levels due to wind on the receive antenna
etc… Off-air using should be in AGC not MGC.
To use the DC2000 for Manual Gain Control determine the signal input level from the input
signal source to the DC2000. Keep in mind that the output level of the DC2000 will be
reduced approximately by the difference from 0dBmV and the level of your input signal.
That is, if you have in input level of -10dBmV, the maximum output level from the DC2000
will be approximately +15dBmV as measured from the top of the haystack.
Switch the MGC switch on the back panel of the DC2000 to “ON.”
With a spectrum analyzer, look at the input source and notice the typical Input Signal.
See
Figure 0.0 (A minimum of 40dBmV from the top of the haystack to the noise floor
should be present for acceptable.)
Figure 0.0

10
Connect the input source to the RF input of the DC2000.
Figure 0.1
Connect a Spectrum Analyzer (recommended) or a Field Strength Meter to the F-connector
marked “IF OUTPUT” on the rear panel of the DC2000 Agile Down Converter.
This Output has a center frequency of 44 MHz.
Using the front panel control marked “MGC LEVEL,” adjust the RF output of the unit
until a carrier-to-noise level is achieved which is close to the carrier-to-noise level of the
input signal. Again, by using the same measurement technique as described in Step c.,
above, the level between the pilot carrier and the noise measured at 1MHz should be very
close to the same. See Figure 0.1