References:
- IRTS sample exam paper 2022 "Amateur Radio Licence Exam In Accordance with ECC/REC/T/R 61-02 HAREC Standard"
Ireland's AC outlet voltage is about 220 volts, that's about 170v RMS.
Power = V x I, I = 2.9A
My answer: A - 3A
Correct!
Valve refers to vacuum tubes. Capacitors don't usually generate heat.
My answer: A - Large value resistors to discharge the capacitors when switched off.
Correct!
3. Consideration for keeping high voltage away from possible human contact when installing a resonant half-wave dipole
I'm fairly certain hazardous voltage can appear throughout the entire length of dipole, however I am unsure what a low pass filter does to a transmitting dipole.
My answer: D - All are equally important; the voltages are the same at all points.
Correct answer: A - the location of the ends of the dipole
Check out the wikipedia article on dipole antenna. The highest of voltages show up at the end of a half-wave dipole antenna:
How half-wave dipole works on receive:
- The incoming RF wave pushes electrons back and forth.
- Consequently, the ends of the dipole are charged.
- The electrical field induces a standing wave of voltage.
- The oscillating current flows down the transmission line and to the receiver.
No idea what a guy rope is, assuming it's just a regular rope.
My answer: D - secure it so that the mast falls away from nearby structures when the rope fails.
Correct answer: B - Secured to the ground, more than 60% of mast's height away from the base.
"Guy rope" is a tensioned cable, adding stability to a free standing structure.
Secure the rope to the ground more than 60% of mast's height away from the base adds to the leverage.
At a distance the mast and rope together will look like a short triangle.
5. What's the most important factor to consider to ensure ham radio station is compliant with radiation exposure limits?
The design of the final amplifier is likely more concerned about efficiency than the leakage.
Filtering at the output stages helps to eliminate undesirable interference but not hugely relevant to radiation exposure.
"Parasitic oscillations" is not relevant to radaition exposure.
The design and location of antenna sounds most appropriate.
My answer: C - the design and location of antenna.
Correct!
6. A 70-Mhz transmitter is causing harmonic interference to TV receiver at 210-Mhz, how to tweak the antenna to eliminate the interference?
I suppose the objective is to make the antenna less efficient radiating RF at 210-Mhz.
The installation of a coaxial stub gives the choice of quarter wavelength at 70 or 210 Mhz, open or closed circuit.
Clues:
- Microwave wave guides are not closed circuit.
- Subject of wave guide is 210 Mhz RF.
My answer: C - open circuit coaxial stub at quarter-wave of 210 Mhz.
Correct!
My answer: A - mixing frequencies in some part of the receiver circuit.
Correct!
My answer: C - passes signals within a frequency range
Correct!
Placing a capacitor in series with the transmitter output simply adds another phase in between the output voltage and current, it does nothing for interference.
Clue: ferrite rings are often seen on DC power supply cables.
Putting a ferrite ring on the hi-fi ssytem's loudspeaker (output) cables probably can help.
Placing a ferrite ring on the transmitter output cable probably won't help.
No idea what an open-wire feeder is, study it later.
My answer: B - putting a ferrite ring on the hi-fi system's loudspeaker output cable.
Correct!
There are two parallel capacitors and an inductor in between.
Capacitors introduce a phase between output voltage and current by introducing a lag in voltage.
Capacitor reactance (opposing AC current) decreases with frequency and capacity.
Inductor let DC (low frequency) pass.
My answer: B - low pass filter.
Correct!
Keep in mind:
- Current leads voltage in a capacitive circuit.
- That's why it takes me hours to charge up a super capacitor using AA batteries.
- Voltage leads current in an inductive circuit.
So for current to lead voltage in an AC circuit, the circuit needs to be capacitive.
My answer: C - capacitive circuit.
Correct!
Power doubles every ~3 dB.
20 - 10 - 5 - 2.5.
My answer: C - 2 watts.
Correct!
There's a capacitor (C) in parallel with an inductor (L).
Capacitors exhibit prominent capacitance below a resonant frequency and exhibit prominent inductance above a resonant frequency.
Inductors let DC (low frequency) pass.
My answer: A - current at the resonant frequency and below will be unaffected.
Correct answer: B
Resources to study:
- https://www.electronics-tutorials.ws/category/accircuits
- https://article.murata.com/en-eu/article/impedance-esr-frequency-characteristics-in-capacitors
Regarding impedance of resistors, inductors, and capacitors:
- Impedance to AC is like resistance to DC. Impedance (Z) is the result of both resistance (R) and reactive (X) components.
- Reactance (X) is always 90 degrees out of phase with resistance (R).
- The higher the reactance, the more out of phase current is.
- Reactance (X) can be either inductive or capacitive.
- Impedance (Z) squared = resistance (R) squared + reactance (X) squared
- Reactance (X) is always 90 degrees out of phase with resistance (R).
- The impedance of a resistor-inductor circuit increases with higher frequency and higher inductance.
- Reactance (X) of a inductor = 2 x pi x frequency x inductance (L)
- Inductors let DC through and impede AC.
- The higher the frequency, the higher the reactance.
- Reactance (X) of a inductor = 2 x pi x frequency x inductance (L)
- The impedance of a resistor-capacitor circuit increases with lower frequency and lower capacitance.
- Reactance (X) of a capacitor = 1 / (2 x pi x frequency x capacitance C)
- Capacitors let AC through and impede DC.
- The higher the frequency, the lower the reactance.
- Reactance (X) of a capacitor = 1 / (2 x pi x frequency x capacitance C)
- The impedance of a resistor-inductor-capacitor circuit???????????
- The impedance "triangle" of an inductor has a positive slope. The impedance "triangle" of a capacitor has a negative slope.
- Reactance (X) = inductive reactance - capacitive reactance
Regarding the correction of power factor:
- Improve AC circuit efficiency = reduce current = reduce the reactance.
- In an inductive AC circuit, inductors cause current to lag behind voltage.
- Add capacitors to slope the impedance "triangle" downward.
Regarding the frequency characteristics of capacitors:
- The impedance (Z) of an ideal capacitor equals to the reactance (X).
- Recap: Reactance = 1 / (2 x pi x frequency x capacitance C)
- The impedance increases with lower frequency and lower capacitance.
- Realistic capacitors have equivalent series resistance and inductance.
- After a certain frequency, the inductance causes the overall impedance to increase.
All about components in series and in parallel:
- Resistors
- Series: R = R1 + R2 ...
- Parallel: R = 1 / (1 / R1 + 1 / R2 ...)
- Inductors
- Series: L = L1 + L2 ...
- Parallel: L = 1 / (1 / L1 + 1 / L2 ...)
- Capacitors
- Series: C = 1 / (1 / C1 + 1 / C2 ...)
- Parallel: C = C1 + C2 ...
- Impedance
- Phew, too complicated.
Revisit the question:
- The circuit has an inductor and capacitor in parallel.
- Similar to resistance in parallel, reactance = R1 x R2 / (R1 + R2)
- Looking at a couple of extreme examples:
- DC flows through the inductor alone, bypassing the capacitor entirely, exhibiting minimal loss.
- High frequency AC flows through the capacitor alone, bypassing the inductor entirely, exhibiting minimal loss.
- In between, the parallel reactance (hence impedance) peaks at the resonant frequency. Therefore the answer is B - the current will be impeded at the resonant frequency.
My answer:
There are 10 nF and 5 nF of capacitance in series. 1 / (1 / 10 + 1 / 5) = 1 / (0.1 + 0.2) = approximately 3.3 nF, answering A.
Correct!
My answer:
- The upper side of the parallel circuit has a total resistance of 60 ohm.
- The equivalent resistance is 1 / (1 / 60 + 1 / 120) = 40 ohm.
- The current flowing through the battery is I = V / R = 6 / 40 = 0.15 amps.
- The ratio of current flowing between the upper and lower side of the circuit is 2 : 1.
- The current flowing through the upper side of the circuit is 0.1 amps.
- The ratio of current flowing through the two resistors is 33 : 27.
- The current flowing through the left resistor is 0.1 / (33 + 27) * 33 = 0.055 amps.
- The closest choice is C - 60 mA.
Correct answer: D
Resistors in serial divide voltage instead of current. I should have stopped at where I calculated the current flowing through the upper side of the circuit.
My answer: Electrolytic capacitor - B.
Correct!
- SSB uses about half the bandwidth of AM transmission, eliminating A.
- For voice transmission SSB does not significantly add to or remove from the fidelity of the audio, eliminating B.
My answer: SSB occupies about half the bandwidth of AM transmission - D.
Correct!
My answer: Its ability to receive weak signals - C.
Correct!
I don't actually recall how SSB transmitter circuit gets rid of the carrier. But in any case speech input is often fed to a modulator.
My answer: balanced modulator - B.
Correct!
Bandwidth of an FM transmission is twice its deviation. FM transmission has fixed bandwidth and it is independent from audio frequency, eliminating A and B.
My answer: twice the deviation frequency - D.
Correct answer: twice the sum of deviation frequency and audio frequency - B
Verified on SDR: FM transmission bandwidth is not independent from audio frequency, the higher the audio frequency the higher the bandwidth!
My answer: 50 ohms - B.
Correct!
22. Which type of feed line is appropriate for when antenna feeder must pass near conductive objects?
Twisted pair (is it the same thing as twisted lead?) let both wires share the same noise and it's commonly used in ethernet cables.
Individual wires without shielding are susceptible to electronic interference.
My answer: coaxial cable - D.
Correct!
ERP is effective radiating power.
My answer: directly proportion to antenna's gain - A.
Correct!
Remember the "open - short - load" calibration method of NanoVNA?
My answer: zero - A.
Correct answer: very high - D
No clue, ask folks from the radio club.
TODO FIXME
Clues:
- The 160m band propagates over the ground rather than being reflected by ionosphere.
- The 160m band is considered by some as being in the "medium wave" band.
- The higher the frequency, the higher its likelihood of penetrating all ionosphere layers.
- RF signals of higher frequencies are also susceptible to being absorbed by atmospheric conditions such as rain.
- The ionosphere layers are, from lowest to highest: D, E, F1, F2.
My answer: RF signal is absorbed by the D layer - B.
Correct!
- Frequency is definitely a factor, e.g. "band is open/closed".
- Mode of transmission is irrelevant to RF propagation, though some modes are more efficient for certain use cases.
- Angle of radiation is definitely a factor, e.g. near vertical incidence skywave.
- For NVIS, radiation angle is driven toward up direction when the antenna is placed closer to ground.
- Height of ionosphere is definitely a factor.
My answer: mode of transmission - B.
Correct!
Note the relatively short distance between the two stations.
- Ground wave is how RF signals on the 160m band usually propagate.
- Sporadic E happens for much higher frequencies, often 6m and above.
- Remember how I received the APRS beacons 500km away?
My answer: ground wave - A.
Correct!
My answer: MUF - B.
Correct answer: critical frequency - A.
Review the concepts of MUF and critical frequency:
- Critical frequency is the one below which RF is reflected and above which RF penetrates through at vertical incidence.
- CritFreq = sqrt(81 x ionisation density).
- Because the critical frequency is measured at vertical incidence, MUF is often much higher.
- MUF is a prediction ("usable"), first of all.
- As a rule of thumb, MUF = 3 x critical frequency.
- MUF = CritFreq / cos(angle of incidence).
My answer: the signal voltage - D.
Correct!
For AC, RMS is approximately 70% of peak voltage.
My answer: 7v - C.
Correct!
Keep in mind that the pass mark of the section A is 60%.
My result: 23 / 30 = 76%, pass!
My answer: november kilo 6 golf romeo - A.
Correct!
My answer: QTH - D.
Correct!
My answer: who's calling me - B.
Correct!
My answer: signal is fading - D.
Correct!
IDs:
- QRA - name
- QRB - distance
- QTH - location
Operational:
- QRP - low power
- QRV - ready
- QRS - slow
Interference:
- QRZ - who's calling?
- QRM - interference
- QRN - static
- QSB - fading
My answer: Mayday - C.
Correct!
My guess: 3.750Mhz - B.
Review this later on for all HF and VHF bands.
Correct answer: 3.760Mhz - D
Study HF band plan: https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf
My answer: 433.5Mhz - C
Correct answer: 433.775Mhz - D
433.5Mhz is the IARU region 1 (Europe & Africa) simplex calling frequency, it is not the amateur radio emergency network's simplex frequency.
References:
- HF band plan: https://www.iaru-r1.org/wp-content/uploads/2021/06/hf_r1_bandplan.pdf
- VHF band plan: https://www.iaru-r1.org/wp-content/uploads/2020/12/VHF-Bandplan.pdf
IARU regions:
- Region 1: Europe and Africa.
- Region 2: Asia and Australia.
- Region 3: North and South America.
General rule of frequency allocation from lowest to highest in each band:
- CW (200 Hz)
- QRP centre of activity is located toward the higher frequencies.
- Narrow-band and digital modes (500 Hz)
- Automatic stations are located toward the higher frequencies.
- Beacons (no bandwidth specified)
- All modes - digital, SSB (2700 Hz)
- All modes - SSB (2700Hz)
- QRP centre of activity is located toward the middle.
- Emergency and SSTV frequencies are located toward the higher frequencies.
HF emergency frequencies:
- 3760 kHz
- 7110 kHz
- 14300 kHz
- 18160 kHz
- 21360 kHz
Some time between May and July 2022 the sample example paper at https://www.irts.ie/dnloads/IRTS_Sample_Exam_Paper_2022.pdf changed to a new revision.
Start over with "IRTS HAREC Sample Examination Paper v1.1.6".
My answer: A - 3Amps.
Correct!
Keep in mind of the inverse square law.
My answer: C - position the antenna so that affected people are in the far field.
Correct!
A dipole antenna has high voltage at the poles and high current in the centre.
My answer: A - ends of the dipole.
Correct!
My answer: B - secured to the ground more than 60% of the mast's height away from the base.
Correct!
My answer: C - the design and location of the antenna.
Correct!
Sounds like improper equipment grounding or the presence of common mode current.
This is probably unrelated to grounding as the Q does not mention hazardous voltage's presence on the equipment.
My answer: D - fit a ferrite ring on computer's cables.
Correct answer: C - use a low-pass filter.
Actually, I don't understand the correct answer of this Q.
My answer: A - mixing of two frequencies somewhere in the receiver (that's the very definition of intermodulation).
Correct!
My answer: C - passes signals between two frequencies
Correct!
My answer: B - put a ferrite ring on the audio system's speaker cables.
Correct!
P = I^2 x R
My answer: D - 500W
Correct!
Remember how I charged up the ultracapacitor?
My answer: C - a capacitive circuit.
Correct!
My answer: B - fast fourier transformation.
Correct!
My answer: D - upper side band.
Correct!
My answer: B - current is impeded at resonant frequency.
Correct!
27 + 33 = 60, total current over both resistors = 100mA.
My answer: D - 100mA.
Correct!
Power doubles roughly every 3 dB. 7dB - 10W, 4dB - 5w, 1dB - 2.5w.
My answer: C - 2W.
Correct!
My answer: D - uses about half the bandwidth of AM.
Correct!
My answer: C - ability to receive weak signals.
Correct!
My answer: B - balanced modulator.
Correct!
My answer: B - twice of (peak deviation frequency + audio frequency).
Correct!
My answer: B - 50 ohm.
Correct!
My answer: D - coax.
Correct!
ERP is the effective radiating power.
My answer: A - proportional to the antenna's gain.
Correct!
My answer: B - match the impedance of transmission line to that of antenna.
Correct!
Remember the layers, from lowest to highest: D, E, F1, F2.
My answer: B - the signal is absorbed by the D layer.
Correct!
My answer: B - mode of the transmission.
Correct!
My answer: A - ground wave.
Correct!
Keep in mind that, the maximum usable frequency is usually 3 x the critical frequency.
My answer: A - the critical frequency.
Correct!
X - time, Y - amplitude.
My answer: D - the signal voltage.
Correct!
From highest to lowest: peek-to-peek, peek, RMS, average.
My answer: C - 7.07V.
Correct!
29/30 = 96%
My answer: A - November Kilo 6 Golf Romeo
Correct!
Keep in mind: QRA - name, QRB - distance, QTH - location.
My answer: D - QTH.
Correct!
Keep in mind: QRZ - who's calling? QSL - please ack.
My answer: B - who's calling?
Correct!
Keep in mind: QRM - interference, QRN - static, QSB - fading.
My answer: D - QSB means fading.
Correct!
My answer: C - Mayday
Correct!
Can I possibly remember these frequencies? lol
My answer: C - 3.630
Correct answer: B
My answer: C - permitted for use unless there's emergency communication in progress.
Correct!
My answer: C - OK.
Correct!
Keywords - offshore, island (land!).
My answer: B - EJ3PA
Correct!
My answer: C - 2E6J
Correct!
Keep in mind: the 160m band spans between 1810 KHZ and 2000 KHZ.
My answer: C - 1853 kHz.
Correct!
Keep in mind: the 80m band spans across 3.5 MHZ and 3.8 MHZ.
My answer: B - CW.
Correct!
Probably one of those WARC bands, including the newly allocated 60m band.
My answer: A - 18.068 - 18.168.
Correct answer: C - 50 MHZ - 52 MHZ.
My answer: D - 7 MHZ - 7.3 MHZ
Correct answer: B - 7MHZ - 7.2 MHZ
My answer: D - wait for DX station to QRZ.
Correct!
My answer: B - "Is this frequency in use, this is XXXXX. (wait and then) CQ from XXXXX."
Correct!
My answer: D - At the beginning and the end of the contact, and every 30 minutes.
Correct answer: C - At the beginning and the end of the contact, and frequently at short intervals.
Remember: readability, signal strength, and CW tone.
My answer: D - readable with difficulty, 5 on the S metre.
Correct!
My answer: C - CQ DX Japan from EI9ABC.
Correct answer: B - CQ Japan from EI8ABC.
My answer: A - general call for a contact.
Correct!
My answer: B - ComReg.
Correct answer: C - To IARU via IRTS liaison officer.
My answer: C - used for low power operation only.
Correct answer: D - should not be used at all.
53. When is the communication between ham stations permitted when stations are in different countries?
My answer: C - the two countries have to be IARU members.
Correct answer: B - permitted by default unless there is unless countries explicitly object.
Remember: A - DSB, F - FM, J - SSB. 1 - Digital, 3 - Analogue. E - Voice.
My answer: A - SSB speech.
Correct!
My answer: D - communicate with anyone on the ham radio frequencies.
Correct answer: C - communicate with ham radio stations on ham radio frequencies. TODO FIXME: but what about in case of emergency?!
M is England.
My answer: B - the holder of EI8XYZ, on a visit to England.
Correct!
My answer: D - no duration restriction.
Correct answer: A - between one and three months
Remember: station ID, time and date, mode, power, frequency, my location (if not at base).
My answer: A - power.
Correct!
Remember: throughout most bands the restriction is 400w, with some notable exceptions such as the 6m and 4m bands.
My answer: C - 50w
Correct answer: D - 25w
Review https://www.comreg.ie/?dlm_download=amateur-station-licence-guidelines first - it's only 32 pages long.
My answer: C - licenses once granted are in fact valid for life.
Correct!
20 / 30 = 66%