Alabama Telecommunications Contractor Examination

What is the nominal characteristic impedance of the coaxial cable used in MATV and cable television distribution systems?

• A50 ohms
• B75 ohms
• C100 ohms
• D300 ohms

In a master antenna television (MATV) system, what does the headend do?

• AIt receives, processes, and combines the incoming signals before they enter the distribut…
• BIt terminates the last outlet on each riser
• CIt supplies 120-volt power to every subscriber outlet
• DIt replaces the need for any amplifiers in the building

A two-way splitter is installed in a 75-ohm distribution system. What is the approximate insertion loss seen at each output port?

• AAbout 0.5 dB
• BAbout 3.5 dB
• CAbout 7 dB
• DAbout 14 dB

A headend delivers +20 dBmV to a riser. The run to the first tap loses 6 dB in cable, a two-way splitter costs 3.5 dB, and the drop loses 4 dB. What level reaches the outlet?

• A+2.5 dBmV
• B+6.5 dBmV
• C+10.5 dBmV
• D+13.5 dBmV

Why is RG-11 sometimes used instead of RG-6 for long coaxial runs in a building distribution system?

• ARG-11 has lower attenuation per 100 feet, so it preserves more signal on long runs
• BRG-11 is rated for 300-ohm systems
• CRG-11 does not require connectors
• DRG-11 carries the return path only

How does coaxial cable attenuation behave as the carried frequency increases?

• AAttenuation increases as frequency increases
• BAttenuation decreases as frequency increases
• CAttenuation is identical at all frequencies
• DAttenuation depends only on connector type

Unused ports on a splitter or tap in a coaxial distribution system should be:

• ALeft open so the system runs cooler
• BCapped with a 75-ohm terminator
• CShorted with a jumper between center conductor and shield
• DFilled with sealant only

In a tapped feeder design, what does a higher tap value (for example 23 dB instead of 8 dB) mean?

• AMore signal is removed from the feeder at that tap
• BLess signal is removed from the feeder at that tap
• CThe tap will not pass the return path
• DThe tap requires no terminator downstream

What is the main drawback of correcting a weak MATV signal by simply adding more amplifier gain?

• AAmplifiers amplify noise and distortion along with the signal, so carrier-to-noise perfor…
• BAmplifiers cannot be used in commercial buildings
• CAmplifier gain reduces the impedance of the cable
• DAmplifiers only work below 50 MHz

Under the National Electrical Code, where must the outer conductive shield of a coaxial cable entering a building be bonded or grounded?

• AAt the farthest outlet from the entrance
• BAs close as practicable to the point of entrance
• COnly at the roof antenna mast
• DAt any convenient panel within 100 feet

For a one- or two-family dwelling, the NEC limits the length of the bonding conductor or grounding electrode conductor serving a coaxial system to a maximum of:

• A6 feet
• B10 feet
• C20 feet
• D50 feet

Which coaxial cable listing is required where cable is installed in a plenum used for environmental air?

• ACATV
• BCATVR
• CCATVP
• DCATVX

A subscriber reports intermittent picture break-up traced to signal ingress on the drop. Which installation defect is the most likely cause?

• APoorly prepared or loose F-connectors that leave the braid unsealed
• BUse of a 75-ohm terminator on an unused port
• CUse of compression connectors instead of crimp connectors
• DBonding the shield at the point of entrance

What is the purpose of adding tilt (or an equalizer) in a coaxial distribution system?

• ATo compensate for the greater cable loss at higher frequencies
• BTo convert the system from 75 ohms to 50 ohms
• CTo physically slope the cable for drainage
• DTo block the return path from reaching the headend

In coaxial distribution, what does the term "drop" refer to?

• AThe vertical elevation change of the cable route
• BThe cable running from the tap or splitter to the individual subscriber outlet
• CThe reduction in signal caused by an amplifier
• DThe point where the coax enters the headend rack

Why is quad-shield coaxial cable specified for drops routed near high-power radio transmitters or heavy electrical equipment?

• AIt provides greater shielding effectiveness against ingress and egress
• BIt changes the cable impedance to reject interference
• CIt eliminates the need for grounding the shield
• DIt carries a higher voltage on the center conductor

An antenna is rated 9 dBd. What is its approximate gain expressed in dBi?

• A6.85 dBi
• B9 dBi
• C11.15 dBi
• D18 dBi

Which antenna type is directional, using a driven element with a reflector and one or more directors?

• AHalf-wave dipole
• BYagi
• CIsotropic radiator
• DGround-plane vertical

What does a VSWR of 1.5:1 on an installed antenna system indicate?

• AAn acceptable match, with a small portion of forward power reflected back down the line
• BA perfect match with zero reflected power
• CAn open or shorted feedline
• DThat the antenna gain has increased by 1.5 dB

Approximately what is one full wavelength, in feet, at 150 MHz?

• A3.3 feet
• B6.6 feet
• C9.8 feet
• D19.7 feet

Two antennas on a microwave path are cross-polarized — one vertical, one horizontal. What is the effect?

• ASubstantial signal loss because the polarizations are mismatched
• BA gain increase of about 3 dB
• CNo effect, because polarization does not matter above 1 GHz
• DThe link automatically converts to circular polarization

For a given frequency, increasing the diameter of a parabolic dish antenna generally produces:

• AHigher gain and a narrower beamwidth
• BHigher gain and a wider beamwidth
• CLower gain and a narrower beamwidth
• DNo change in gain or beamwidth

Why are transmission-line grounding kits installed on coaxial feedlines running up a tower?

• ATo divert lightning-induced current on the line shield to the tower ground system before…
• BTo increase the gain of the antenna
• CTo hold the line against the tower in place of hoisting grips
• DTo match the antenna impedance to the radio

When routing coaxial transmission line up a tower, why must the manufacturer's minimum bend radius be observed?

• AExceeding it deforms the dielectric and shield, raising VSWR and loss permanently
• BIt only affects the color coding of the jacket
• CTight bends increase the antenna gain
• DBend radius applies only to fiber, not coax

What is the purpose of a line sweep test performed after installing an antenna and its feedline?

• ATo verify return loss or VSWR across the operating band and locate faults along the line
• BTo measure the concrete strength of the tower foundation
• CTo confirm the tower's painting and lighting compliance
• DTo measure wind speed at the antenna elevation

Which structural standard establishes design criteria for antenna supporting structures, antennas, and their mounts?

• AANSI/TIA-222
• BANSI/TIA-568
• CASTM C143
• DAWS D1.4

Before adding new antennas and lines to an existing tower, what must normally be confirmed?

• AThat a current structural analysis shows the tower can carry the added loading
• BThat the new antennas are the same color as the old ones
• CThat the crew has climbed that tower before
• DThat the added antennas weigh less than 100 pounds total

Why is hardline (rigid or corrugated) coaxial transmission line preferred over flexible coax for long tower runs?

• AIt has significantly lower attenuation and better power handling
• BIt does not require weatherproofing at connectors
• CIt can be bent to any radius without damage
• DIt has a 300-ohm impedance for antenna feeds

What is the accepted way to weatherproof an outdoor coaxial connector at an antenna?

• ASeal the connection with butyl mastic and overwrap with electrical tape in overlapping la…
• BLeave it open so condensation can drain
• CFill the connector body with grease and leave it uncovered
• DWrap it only with duct tape

A point-to-point link is failing even though both antennas are aligned. Trees have grown along the middle of the path. What is the most likely cause?

• AObstruction of the Fresnel zone along the path
• BIncorrect concrete strength in the tower foundation
• CExcess grounding at the equipment shelter
• DUse of 75-ohm terminators at the radios

What does mechanical downtilt of a sector antenna accomplish?

• AIt aims the main beam downward to concentrate coverage closer to the tower
• BIt increases the antenna's rated gain
• CIt converts the antenna to circular polarization
• DIt eliminates the need for a structural analysis

Which document governs the marking and lighting of a new antenna structure that exceeds 200 feet above ground level?

• AFAA obstruction marking and lighting requirements based on a filed FAA Form 7460-1 study
• BASTM C31 field sampling procedures
• CThe National Electrical Code Article 250
• DThe manufacturer's antenna pattern sheet

A tower foundation requires 486 cubic feet of concrete. How many cubic yards should be ordered before any waste allowance?

• A12 cubic yards
• B18 cubic yards
• C27 cubic yards
• D54 cubic yards

A drilled pier for a monopole is 4 feet in diameter and 25 feet deep. Approximately how many cubic yards of concrete are required?

• A8.7 cubic yards
• B11.6 cubic yards
• C14.5 cubic yards
• D23.3 cubic yards

What is the primary effect of increasing the water-cement ratio of a concrete mix?

• ACompressive strength and durability decrease
• BCompressive strength increases
• CSet time is unaffected and strength rises
• DAir content is automatically corrected

Which ASTM test method is used to measure the slump of freshly mixed concrete?

• AASTM C31
• BASTM C39
• CASTM C143
• DASTM C231

Concrete compressive strength is normally specified and accepted at what age?

• A3 days
• B7 days
• C28 days
• D90 days

Under OSHA steel erection rules, before a contractor may begin erecting steel on a foundation, the concrete must have attained:

• AAny measurable strength, as judged by the crew
• BAt least 75 percent of the intended minimum compressive design strength, or sufficient st…
• C100 percent of design strength in every case
• D50 percent of design strength within 24 hours

What is the minimum concrete cover normally required over reinforcing steel in concrete cast against and permanently exposed to earth?

• A3/4 inch
• B1 1/2 inches
• C2 inches
• D3 inches

What is the main purpose of intentionally entrained air in concrete exposed to weather?

• ATo resist damage from freezing and thawing cycles
• BTo increase compressive strength
• CTo make the concrete set faster
• DTo eliminate the need for curing

Which material is specified for filling the space between a base plate and its concrete foundation after a monopole or equipment frame is set and leveled?

• ANon-shrink grout
• BOrdinary mortar mixed on site
• CExpanding foam
• DDry sand tamped in place

What is the primary function of an anchor bolt template during a tower foundation pour?

• ATo hold the anchor rods in the exact pattern, elevation, and plumb required by the base p…
• BTo keep concrete from splashing on the rebar
• CTo measure the slump of the delivered concrete
• DTo act as permanent structural reinforcement

Under OSHA steel erection requirements, anchor rods (anchor bolts) may be repaired, replaced, or field-modified only:

• AWith the approval of the project structural engineer of record
• BAt the discretion of the erection foreman
• CIf the change is less than one inch
• DAfter the structure is fully erected

How many anchor rods must a column have at minimum under OSHA steel erection rules?

• ATwo
• BThree
• CFour
• DSix

Why is concrete for a drilled shaft normally placed by tremie or pump when water is present in the hole?

• ATo place concrete from the bottom up and displace water without washing cement from the m…
• BTo reduce the amount of concrete needed
• CTo eliminate the need for reinforcing steel
• DTo allow the concrete to set faster