Coaxial Dynamics 86735 User manual

Coaxial Dynamics
A CDI INDUSTRIES, INC. COMPANY
SPECIALISTS IN RF TEST EQUIPMENT & COMPONENTS
6800 Lake Abram Drive
Middleburg Heights, OH 44130
Telephone: [phone]
Fax: [phone]
Web Site: www.coaxial.com
E-mail: [email protected]
Instruction Manual
Model 86735
RF Air-Cooled
Coaxial Load

LIMITED WARRANTY
We take pride in manufacturing products of the highest quality and we warrant them to
the original purchaser to be free from defects in material and workmanship for the period of one
year from date of invoice.
Additionally, products of our manufacture repaired by us are warranted against defects in
material and workmanship for a period of 90 days from date of invoice, with the provisions
described herein.
Should a product, or a portion of a product of our manufacture prove faulty, in material
or workmanship, during the life of this warranty, we hereby obligate ourselves, at our own
discretion, to repair or replace such portions of the product as required to remedy such defect. If,
in our judgment, such repair or replacement fails to be a satisfactory solution, our limit of
obligation shall be no more than full refund of the purchase price.
This warranty is limited to products of our own manufacture. Equipment and
components originating from other manufacturers are warranted only to the limits of that
manufacturer's warranty to us. Furthermore, we shall not be liable for any injury, loss or
damage, direct or consequential, arising out of the use, or misuse (by operation above rated
capacities, repairs not made by us, or any misapplication) of the equipment.
Before using, the user shall determine the suitability of the product for the intended use;
and the user assumes all risk and liability whatsoever in connection therewith.
The foregoing is the only warranty of Coaxial Dynamics and is in lieu of all other
warranties expressed or implied.
Warranty returns shall first be authorized by the Customer Service Department and shall
be shipped prepaid.
86735 Rev. Dec. 2000 - 2 - Coaxial Dynamics

INTRODUCTION
This manual gives you specific information on the installation, operation and service
Model 86735 Series Air-Cooled Coaxial Load. Most of the loads are field serviceable, but we
recommend their return to us for repair. Mistakes can be costly compared to the low cost for our
trained personnel to make the repairs and return the load to new performance specifications.
Labor and packaging costs are minimal. We take the load completely apart, clean and inspect all
parts, repair/replace as necessary, reassemble, power test, VSWR test and package the load for
shipment. If new parts are required in the load (such as resistors etc.), this will be an additional
cost. The average turn-around time on repairs is approximately 10 working days and generally
will depend on your needs. When sending in repairs, please include: your company name and
address, the operating frequency you use, fax number, telephone number and your name in case
we need to talk to you about the load or obtain shipping instructions. We can accommodate
most shipping methods.
SHIP TO: Coaxial Dynamics
6800 Lake Abram Drive
Middleburg Heights, Ohio, USA 44130
For information call: 1-800-COAXIAL (1-800-262-9425)
86735 Rev. Dec. 2000 - 3 - Coaxial Dynamics

TABLE OF CONTENTS
MODEL 86735
SECTION PAGE
Warranty .............................................................................................................2
Introduction.........................................................................................................3
Precautions..........................................................................................................6
I. Description and Leading Particulars
1-1 Purpose and Application of Equipment........................................7
1-2 Equipment Supplied .....................................................................7
1-3 Equipment Required But Not Supplied........................................7
1-4 General Description......................................................................7
1-5 Electrical Description ...................................................................7
1-6 Mechanical Description................................................................8
1-7 General Principle of Operation.....................................................8
1-8 Operating and Adjustment Controls.............................................8
II. Test Equipment and Special Tools
2-1 Test Equipment Required .............................................................9
2-2 Special Tools Required.................................................................9
III. Preparation for Use and Reshipment
3-1 Unpacking Equipment ................................................................10
3-2 Pre-Installation Inspection..........................................................10
3-3 Pre-installation Test....................................................................10
3-4 Installation ..................................................................................10
3-5 Location.................................................................................10,11
3-6 Mounting ....................................................................................11
3-7 Connections ................................................................................11
3-8 Ducting ..................................................................................11,12
3-9 Adjustments................................................................................12
3-10 Preparation for Reshipment .......................................................12
IV. Theory of Operation
4-1 General .......................................................................................13
4-2 Control Circuits ..........................................................................13
86735 Rev. Dec. 2000 - 4 - Coaxial Dynamics

TABLE OF CONTENTS (cont’d)
MODEL 86735
SECTION PAGE
V. Maintenance
5-1 Cleaning......................................................................................14
5-2 Lubrication .................................................................................14
5-3 RF Circuit (including resistor replacement)..........................14,15
VI. Diagrams
Schematic Diagrams .................................................................... 16-18
Parts List ............................................................................................19
VII. Specifications...........................................................................................20
VIII. Illustrations
Model 86735 RF Coaxial Air-Cooled Load .................................cover
Vertical Side Panel Displaced............................................................21
Access Panels Displaced/Resistor Assembly ....................................22
PRECAUTIONS
86735 Rev. Dec. 2000 - 5 - Coaxial Dynamics

CAUTION
Do not block air grills;
blocking air flow can cause unit to fail!
OWARNINGO
Do not attempt any service or parts replacement without first
disconnecting all AC power and RF power. Failure to do so
may result in serious or fatal electrical shock.
CAUTION
Do not apply more than rated power to unit. Damage will occur
before thermal protectors can activate interlock circuit if large
overloads are applied.
1CAUTION1
When using any cleaning solvents or solutions, assure that there is
adequate ventilation to protect personnel from breathing any
irritable or possibly toxic fumes.
OPERATING TEMPERATURE
WARNING
CARE SHOULD BE TAKEN TO OPERATE UNIT BELOW STATED
MAXIMUM AMBIENT OPERATING TEMPERATURE.
OPERATION ABOVE RATED AMBIENT
TEMPERATURE MAY CAUSE MOTOR THERMAL
PROTECTION TO SHUT OFF FAN, WHICH MAY
CAUSE DAMAGE TO UNIT.
PROVISIONS ARE MADE TO TRIP THE INTERLOCK
IN THE EVENT OF OVERHEAT, BUT THE INTERLOCK
MUST BE PROPERLY CONNECTED TO THE RF SOURCE
FOR THIS FUNCTION TO OPERATE.
NEVER OPERATE WITH INTERLOCK
DISCONNECTED OR MALFUNCTIONING.
SECTION I
86735 Rev. Dec. 2000 - 6 - Coaxial Dynamics

DESCRIPTION AND LEADING PARTICULARS
1-1. Purpose and Application of Equipment. The Model 86735 Coaxial Load is designed to
safely dissipate a maximum of 35,000 watts of electrical energy over a frequency range of
DC to 220 Mhz.
1-2. Equipment Supplied. The Model 86735 Coaxial Load is supplied with standard RF
connectors. Their designations are:
3 1/8 EIA Swivel flange: ....................................Model 86735-1
3 1/8 Unflanged recessed: ....................................Model 86735-2
3 1/8 Unflanged flush: ....................................Model 86735-3
The standard power supply voltages and their designators after the Model # are:
-110: 110-120VAC, single phase, 50/60 Hz
-230: 208-230VAC, single phase, 50/60 Hz
-380: 380VAC, single phase, 50 Hz
1-3. Equipment Required But Not Supplied. The Model 86735 Coaxial Load is complete as
supplied, but the user must furnish AC Mains input, RF input, interlock control cable and
ground cable appropriate to each installation.
1-4. General Description. The Model 86735 Coaxial Load is enclosed in a single aluminum
case which is painted with a durable acrylic finish. Power connection is made through an
IEC connector on the rear panel of the enclosure (200-240 volt models use a multi-contact,
twist-lock style connector on the rear panel). This panel also contains a 4-screw barrier
terminal strip for connection of the interlock circuit and a 1/4-20 UNC-2B stud for
attachment of the ground. The RF connector is located in the center of the top panel.
1-5. Electrical Description. The Model 86735 contains a 50 ohm non-reactive resistor
assembly capable of dissipating 35,000 watts of applied electrical energy at sea level at
frequencies between DC and 220 Mhz with a maximum VSWR of 1.15 to 1. No
provisions are made for tuning the resistor assembly and all operating controls relate to the
operation of the blower assembly. The blower control circuit consists of three switches
wired in parallel to control the blower motor contactor. Power is supplied to this contactor
and to the "Blower On" lamp whenever the equipment is attached to the correct power
supply and the main power switch is "ON" or when one of the fan thermostats senses a
temperature equal to or greater than 120°(±7°) F. The transmitter interlock circuit
consists of two thermal switches wired in series to control the interlock relay. Power is
supplied to this relay whenever the equipment is attached to the correct power supply and
neither of the overtemperature thermal switches senses a temperature equal to or greater
than 250°(±7°) F. A lamp is provided to indicate when one or more of the
overtemperature switches opens. It is labeled "OVERHEAT", indicating a change in state
of the interlock.
86735 Rev. Dec. 2000 - 7 - Coaxial Dynamics

SECTION I (cont’d)
DESCRIPTION AND LEADING PARTICULARS
1-6. Mechanical Description. The Model 86735 RF Coaxial Load is a 50 ohm non-reactive
resistor assembly which is cooled by forced ambient air. The blower assembly is a 3/4 HP
direct-drive centrifugal blower. The blower moves air from floor level into a closed
plenum surrounding the resistor assembly. Air then enters the resistor assembly and flows
downward through it to the transition duct and then out of the enclosure via the discharge
grill. This places the RF input connector at the coolest point in the air stream and affords
exceptionally quiet operation.
1-7. General Principle of Operation. After ascertaining that the Model 86735 is connected to
the correct power supply, connect the transmitter interlock circuit and RF source. Turn the
main power switch ON to start the fan and enable transmitter. Operate transmitter as
desired.To stop operation, it is necessary to first turn off the transmitter, then the main
power switch on the Model 86735. The fan may continue to run for some time. This
depends upon the power level at which the load was operating and upon the ambient air
temperature. This feature is necessary to prevent damage to the load. The Model 86735
can be operated in a "Standby" or "Reject" mode with the blower off. Current draw in this
mode is 60 milliamperes. To operate in this mode, connect the unit as before and leave the
main power switch on the front panel "Off". It is highly recommended that the normally
open pair on the interlock terminal board be used to control a user-supplied alarm circuit.
This pair will close on power failure or overheat, and the alarm, if independent of the AC
power supply for the unit, will notify the operator of a fault.
1-8. Operating and Adjustment Controls. The only operating control is the main power
switch. No field adjustments are necessary or possible.
86735 Rev. Dec. 2000 - 8 - Coaxial Dynamics

SECTION II
TEST EQUIPMENT AND SPECIAL TOOLS
2-1. Test Equipment Required. No test equipment is required for routine maintenance. In
some circumstances it may be desirable to determine the temperature differential (outlet air
minus inlet air) and ambient air temperature which the equipment is experiencing. We
recommend the John B. Fluke Mfg. Co. Model 52 or equivalent instrument for this
function.
2-2. Special Tools Required. Although no non-standard tools are required for routine
maintenance, we recommend the technician have the following specialized tools available:
1 Torx T-15 driver
1 Tee handle hex key, 7/32" bit
1 Power screwdriver with 7/32" hex key & torx T-15 bit
86735 Rev. Dec. 2000 - 9 - Coaxial Dynamics