What is the frequency of the VCO used in the first modulation step in the TX Unit?
8192kHz
What are not designed to break current, including load current from long bus sections?
Hot stick operated disconnect links
Parallel resistance is?
inverse
1/1/r1+1/r2+1/r3
What is Ohm's Law?
E = IxR
A measurement of -75dBm, F1A weighted equals? dBrnC
13dBrnc
-75 + 82 = 7
7 + 6 = 13dBrnc
When multiple frequencies at an input produce sum and difference frequencies at the output, this is called?
Intermodulation
Explain the function of an RTS
Relay Transfer Switch: used to transfer protection functions to the bus-tie trip circuit during an outage to any of the dedicated PCSs or lines
What is the BPA spec for total RMS harmonic distortion?
Shall not exceed one percent for a 1000Hz test tone at a full test tone of 0dBm0
What is non-linear of harmonic distortion?
a production of a harmonic
If baseband traffic is removed from either transmitter at your distant end and you have your receiver in the manual position what happens?
The receiver baseband circuit will drop 6dB
What is an acceptable value when measuring PAR?
92
How do you measure envelope delay?
perform a PAR test
Explain the function of a SER
sequential events recorder
T/F
Envelope delay has a greater effect on voice than it does on data?
False
Envelope Delay: when different frequencies travel at different speeds
What is the highest baseband frequency in a 960 channel FDM plan?
4028 kHz
What is the first step when completing maintenance on an NEC radio?
Call the distant end district to check the status of the other radios.
Place the maintenance switches into maintenance
This sends maintenance alarms to CSM and badger/open-i
What is the formula for power?
P = IxE
P = I2 x R
P = V2/R
If you remove the output cable from an FM Demod without locking on to the other receiver, what happens?
The receiver baseband drops 3dB
What is the frequency of the synchronizing pilot?
308kHz
Why is only one sideband transmitted in SSBSC multiplexing?
Lower power and bandwidth required
Is the impedence of the VF jackfield balanced or unbalanced?
balanced with reference to ground
Portable protective grounds are not required between phases to accomplish the visible three phase short provided the ground switch structure has above ground metallic structure interconnections between phases on what type of connections?
Series capacitors
Shunt capacitors
Who typically wears a red or orange vest while performing their duties?
Safety watcher
T/F
A zero transmission level point (TLP) is a point where full level power is 0dBm
True
Explain the three types of faults that can occur on a three phase power system.
Phase to phase
Phase to ground
Phase to Phase to ground
Explain the ROWS alarm and what is meant when it goes off
Remote operated warning system
Indicates remote operation of equipment in the substation yard
A safety watcher is required any time mechanical equipment is working closer than ? on circuits up to 345kV or ? on 500kV circuits.
15 ft
20 ft
db Conversions
1)dBm to dBa
2)dBa0
3)dBrnc
4)dBrnc0
1)Add 85 for pure tone, 82 for F1A weighting, 77 for 601A/F1A weighting
2) Calculate dBa then subtract the tlp
3) Calculate dBa then add 6
4) Calculate dBrnc then subtract the tlp
If a piece of high voltage equipment is cleared and isolated but not grounded is MAD still applicable?
Yes
A BPA employee who has an electrical workers permit and access to energized facilities is a?
Qualified Electrical Employee
What is the minimum approach distance for a fiber optic splice box?
24 inches
0 dBm equals?
1mW
Your western electric 3A test set meter reading is 23 at a tlp of -8dBm. What is the reading in dBrnc0?
31 dBrnc0
23 -(-8) = 31
What is the level of the pilot at the BB Mon out point on the receiver?
-42.9 when locked on
What is phase jitter
The continuing movement back and forth in the phase of the received signal.
What is frequency displacement?
A shift in frequency of the received signal vs. the transmit.
What is the full test tone level at the FM DEM BB out Mon point?
-35dBm
What is the baseband test tone frequency at crossover?
2568 kHz
When making a measurement of a test tone you have accidentally double terminated the test point, what will your reading be?
3dB low
What are the lights on the mimic bus? What do they mean?
White - provides an indication of the ability to close the PCB
Amber - indicates the line is hot
Red - indicates the breaker is closed
Green - indicates the breaker is open
What is the BPA specification for frequency stability of the readio transmitter?
+/- .005%
What is meant by intrinsic or idle noise?
White noise
the noise present on a channel when not used
noise coming from a bad power supply
Voltage Identification
1)Orange
2)69kv
3)Black
4)115kv
5)Red
13.8kv
green
500kv
yellow
230kv
What is an acceptable level for attenuation distortion or frequency response?
+/- 1dB at 300-3400hz
On the HF line unit what is the tlp of the T jack?
-46dBm
The HF line unit low pass filter attenuates frequencies above what frequency?
4200hz
T/F
In the non-sync mode, the free-running 128khz is measure at the F jack on the front of the channel unit?
True
What is the maximum number of channels that can be supplied by a single 84842 sync unit?
300
When making measurements at the T or R jack on the HF line unit, what impedance settings should you use on your frequency selective level meter?
75 ohms terminated
What is the free running frequency stability of the channel unit?
1 x 10 to the 6
In the channel unit, how many modulation steps are there to change VF to HF?
2
What signal is provided by the sync unit to synchronize frequency generation in the channel unit?
128khz
What is the maximum number of channel shelves that can be supported by a single HF line unit?
7
In the channel unit, the first modulator mixes the VF input with what carrier frequency?
8192khz
A received signal enters the channel unit and passes through how many demodulation steps for HF to VF conversion?
2
How many channels are there in 16 supergroups?
960
T/F
Noise from a power supply or ring generator can cause phase jitter?
True
What is an acceptable amount of phase jitter?
10 degrees
What is the BPA specification for the 308khz synchronizing pilot?
+/- .5hz
Thermal noise is also known as?
White Noise
Noise that is introduced during the conversion of analog to digital and back is called?
Quantization noise
Which filter gives the best measurement of 60hz noise?
3-khz flat
The c-message filter is calibrated so that with 0dBm at 1khz into the measuring instrument the reading is?
+90dBrnC
The number of dB the signal is above noise is referred to as?
Signal to noise ratio
Which circuit determines which receiver to lock on to during a mute condition?
The common circuit
Over what range of temperatures must the RF equipment work?
0 to 50 degrees C
What intermodulation plus idle noise would be allowed in the worst 3.1khz slot on a baseband consisting of 10 hops?
55dB s/n
What is the formula for power?
P = IxE
P = I2 x R
p = V2/R
The term 30dB would tell you what?
The relationship of two powers to each other
The correct symbol for decibel is?
dB
The difference (in dB) between the RF received level and the practical threshold (squelch or mute point) is called?
Fade Margin
The difference between signal strength at a given point and a reference level is?
Level
Interfering effect of noise, C message weighted is?
dBrnC
F1A weighting refers to?
a handset
Reading a 58 on your Western Electric 3A test set at a +7tlp equals ? dBrnC0
51 dBrnC0
In the channel unit, the second modulator carrier is?
Switch selectable
Reading a -58 dBm, F1A weighted on a flat meter at a +7tlp is equal to ? dBa0
-58 + 82 = 24
24 - (+7) = 17
To measure the level of voice and music we use a ? meter?
VU
At a -4 dBm test point your flat meter reading is -68dBm, F1A weighted. The dBrnC0 reading is?
-68 + 82 = 14
14 + 6 = 20
20 -(-4) = 24 dBrnC0
The ratio between 2 powers is?
dB
The actual amount of power above or below a reference of one milliwatt?
dBm
What is the basic bandwidth of a voice circuit?
300--3400hz
What is attenuation distortion?
A change in amplitude of the signal versus the frequency.
How do we measure attenuation distortion?
After establishing a reference level, sweep the channel from 200hz to 4000hz, noting any differences in the amplitude in the 300-3400hz range greater than +/- 1dB
If you measure the 308khz pilot on the baseband and it's -7dBm0 then its?
3 dB hot
When a clearance holder releases a clearance on a line or equipment that is ready for service the dispatcher or switchman must be assured that?
All workers and ppe are in the clear
All portable protective grounds have been removed
The released line or equipment is ready for service
All isolating devices and ground switches within the limits of the clearance have been left as found
T/F
A P/AR reading of 82 is within specs for a BPA channel with 2 hops?
False
Another name for "go and return" crosstalk is?
Turnaround
The highest supergroup accommodated by the 46A3 is?
16
What is the impedence at the mod/demod jacks for the VF jackfield?
600 ohms
Receiver Baseband Level Checks
Go
***Lock onto the receiver not under test
Baseband OSC @ 2568khz +2dBm
RF Generator set to receive frequency
Besel the RF Gen with the Spectrum Analyzer
Reset the BB OSC to -26.8 below the beleled level
Output normal AGC into the RX SMA
Read 35.2dBm +/-0dB
What is the free running frequency stability of the sync unit?
1 x 10 to the 6
Receiver Continuity Pilot Alarm Point
Go
*** Verify you are locked onto the receiver not under test
Set RF Gen to output normal AGC
Tune FSVM to 4715khz and set the output so that you read -42.9dBm at the BB Mon port
Create Pilot alarm (-6dBm +/- 1 from norm)
Clear Pilot alarm (-3.5dBm +/- 1 from norm)
-45.4 to -47.4 dBm
Reading you would get if the test tone was 0dBm?
dBa0
AGC or NDF alarm
GO
Verify you are outputting normal AGC
reduce RF generator until NDF alarm occurs
Measure voltage difference for 0.6vdc +/-.1 for alarm
0.4vdc +/-.1 for clear
What is impulse noise?
Short duration spikes or noise burst typically lasting 1 m.s. or less.
On the HF line unit, what is the tlp of the R jack?
-64dBm
What is a phase hit?
A sudden change in the phase of the receive signal vs. the transmit signal lasting longer than 4 m.s.
What must a workman do to verify the circuit is de-energized before applying portable protective grounds?
Perform a "buzzing test" on each phase with the metal head of a live line tool or with a "voltage detector".
dB above -90dBm at 1000hz C message weighted:
dBnrC
According to the 46A3 manufacterer specs, what is the maximum permissible VF return loss?
26 dB minimum
According to the 46A3 manufacturer specs, the maximum per channel carrier leak is?
-42dBm0
dBrn is a measure of the number of ? of interference above the reference noise level?
dB
The primary analog microwave backbone radios operate in what frequency range?
8 ghz
What is delay distortion or envelope delay?
A change in delay over the circuit versus frequency.
Interference F1A weighted above reference:?
dBa
Noise power, psophometrically weighted is?
pWp
The difference between 2 powers?
level
Which sideband is used for supergroup 0, group 1, channel 10?
lower
What does the weighting curve show?
The interfering effect of other frequencies in a voice channel compared with a reference frequency of 1000hz
What does a caution tag represent?
Equipment or controls that are unsafe or hazardous
What does a hold order represent?
Control points associated with a hold order
What does a work permit represent?
power system equipment or circuits that are being worked on
What does a do not operate tag represent?
Isolating devices that are the limits of a clearance
Electrical barriers are?
used to prevent contact with energized parts
T/F
Qualified electrical employees may enter an area guarded by a yellow and black rope?
True
What is a dropout?
Short term decrease in signal level orf more than 12db lasting for longer than 4m.s.
T/F
A tone of 1khz causes more interference than do other frequencies?
True
At what power level does 1khz tone cause zero interference? (144 weighted)
-90 dBm
Reference noise is?
1) a noise that creates the same interfering effect as a 1000hz -90-dBm tone
2) a noise that creates zero dBrn in a voice channel
Power is ?
a definite amount of work done over time
rate at which energy is used
What is the frequency range for the 8 ghz microwave radio?
