ASOC Exam: Last minute Study Aid
Ready Reference Tables
Q Codes
NATO Phonetics
RST Signal Report
Emission Classifications
Resistor Color Code
RF wave spectrum
Abbreviations
Common Q Codes (Radio Amateur): Communicating with Other Hams
Q Code Question Answer/Advice QRL Are you busy? I am busy (or I am busy with _________) QRK What is the intelligibility of my signals? The intelligibility of your signals is… QRM Are you being interfered with? I am being interfered with. QRN Are you troubled by static? I am troubled by static. QRO Shall I increase transmitter power? increase transmitter power. QRP Shall I decrease transmitter power? Decrease transmitter power. QRT Shall I stop sending? Stop sending. QRU Have you anything for me? I have nothing for you. QRV Are you ready? I am ready. QRX When will you call me again? I will call you again at… QRZ Who is calling me? You are being called by… QSB Are my signals fading? Your signals are fading. QSL Can you acknowledge receipt? I acknowledge receipt. QSO Can you communicate with…direct? I can communicate with…direct. QSP Will you relay to ______? I will relay to ______. QSY Shall I change frequency? Change frequency. QTC How many messages have you to send? I have ______messages for you QTH What is your location? My location is… QTH What is the correct time? The time is____
ICAO/NATO Phonetic Alphabet (officially the International Radiotelephony Spelling Alphabet)(Words are chosen for their distinct sounds to reduce errors.)
Letter Code Word Letter Code Word A Alfa N November B Bravo O Oscar C Charlie P Papa D Delta Q Quebec E Echo R Romeo F Foxtrot S Sierra G Golf T Tango H Hotel U Uniform I India V Victor J Juliett W Whiskey K Kilo X X-ray L Lima Y Yankee M Mike Z Zulu
Digits (India/HAM usage): 1 – Wun, 2 – Too, 3 – Thuh-ree, 4 – Fo-wer, 5 – Fi-yiv, 6 – Six, 7 – Sev-en, 8 – Ait, 9 – Nin-er, 0 – Zero
RST Signal Report (Readability, Strength, Tone)
Number Readability (R) Strength (S) Tone (T) – CW only 1 Unreadable Faint, barely perceptible Very rough, broad AC 2 Barely readable, occasional words Very weak Very rough AC, very harsh 3 Readable with difficulty Weak Low note, rough and broad 4 Readable, no difficulty Fair Rather rough note 5 Perfectly readable Fairly good Normal AC note 6 — Good Modulation good 7 — Moderately strong Pure AC, several musical notes 8 — Very strong Pure AC, slightly musical 9 — Extremely strong Pure AC, very musical notes
Emission Classifications (ITU)
Format: X Y Z (Modulation Type, Nature of Signal, Type of Information)
Code Modulation Type Nature of Signal Type of Information A1A Unmodulated carrier, morse (CW) Telegraphy (on-off keying) No subcarrier A3E Amplitude, full carrier, double sideband Telephony (analog) None J3E Amplitude, suppressed carrier, single sideband Telephony (analog) None F3E Frequency modulation Telephony (analog) None C3F Vestigial sideband, analog Vestigial sideband (analog) None H3E SSB, full carrier, telephony Telephony (analog) None
Example : J3E = SSB suppressed carrier, telephony
Resistor Color Code
Color Digit Multiplier Tolerance Black 0 1 — Brown 1 10 ±1% Red 2 100 ±2% Orange 3 1000 — Yellow 4 10,000 — Green 5 100,000 ±0.5% Blue 6 1,000,000 ±0.25% Violet 7 10,000,000 ±0.1% Grey 8 — — White 9 — — Gold — 0.1 ±5% Silver — 0.01 ±10%
Mnemonic : "BBROY of Great Britain had a Very Good Wife" (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White)
The radio spectrum is divided into several bands based on frequency:
Band Name Abbr. Frequency Range Propagation Use Very Low Frequency VLF 3–30 kHz Ground wave Navigation, military Low Frequency LF 30–300 kHz Ground wave NDB, AM broadcast Medium Frequency MF 300–3000 kHz Ground & sky wave AM broadcast, maritime High Frequency HF 3–30 MHz Sky wave (ionospheric) Shortwave, ham, aviation Very High Frequency VHF 30–300 MHz Space wave (line-of-sight) FM, TV, aviation, ham (144–146 MHz) Ultra High Frequency UHF 300–3000 MHz Space wave Mobile, TV, radar, satellite Super High Frequency SHF 3–30 GHz Space wave Microwave, satellite, radar Extremely High Frequency EHF 30–300 GHz Space wave Experimental, satellite
Air Band: VHF 118–137 MHz (civil aviation), UHF 225–400 MHz (military aviation)
Here is a non exhaustive list of commonly used ham radio abbreviations,
Abbreviation Meaning Abbreviation Meaning ABT About ANT Antenna AGN Again BK Break CFM Confirm CLR Clear CQ General call CW Morse code DE From DX Long distance contact GA Go ahead/Good afternoon GND Ground HW? How do you copy me? HI Laughter on CW K Please transmit KN Only the station I am working LP Log-periodic antenna or long path LSB Lower sideband MSG Message NIL Nothing heard or no copy OM Old man (amateur radio operator) PSE Please R Message received or correct RX Receiver SIG Signal SK This is my last transmission (stop keying) STN Station SWL Short waves listener TU Thank you TX Transmitter TCVR Transceiver UR Your USB Upper sideband WPM Words Per Minute WX Weather XCVR Transceiver XMTR Transmitter XTAL Crystal XYL Wife YL Young lady 73 Best regards 88 Love and kisses
Chapter I: Resistors, Capacitors, Inductors, Transformers
Key Points
Resistor: Limits current. Color code for value, tolerance, and (sometimes) temp. coefficient.Capacitor: Stores charge, blocks DC, passes AC. Series 1/C = 1/C1 + 1/C2 + ... ; Parallel C = C1 + C2 + ... .Inductor: Stores energy in magnetic field, opposes change in current. Series L = L1 + L2 + ... ; Parallel 1/L = 1/L1 + 1/L2 + ... .Transformer: Steps up/down voltage/current. Vp/Vs = Np/Ns = Is/Ip .Ohm’s Law: V = I × R , I = V/R , R = V/I .Power: P = VI = I²R = V²/R .Conductors vs Insulators: Conductors allow current (metals); insulators block (rubber, plastic, glass).Series/Parallel: Series adds resistances/inductances, reduces capacitances. Parallel adds capacitances, reduces resistances/inductances.
Mnemonic: "BBROY of Great Britain had a Very Good Wife" (Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White)
Chapter II: Semiconductors, Diodes, Transistors
Key Points
Semiconductor: Silicon, Germanium. Doping (N-type: extra electrons, P-type: extra holes).Diode: PN junction. Forward bias: conducts. Reverse bias: blocks. Symbol: →|—.Rectifiers: Half-wave (one diode), Full-wave (center-tap or bridge). Bridge uses four diodes, no center tap needed.Zener Diode: Breakdown in reverse for voltage regulation.LED: Emits light when forward biased. Longer lead = anode (+).Transistor (BJT): NPN/PNP. Terminals: Emitter (E), Base (B), Collector (C). Amplifies current.Configurations: Common Emitter (high gain, phase inversion), Common Collector (emitter follower, high current gain), Common Base (high frequency).Darlington Pair: Two transistors for very high current gain.
Diode Direction: Arrow shows conventional current flow (anode to cathode).
Chapter III: Amplifiers, Oscillators, Filters
Key Points
Amplifier Classes: A (linear, low distortion), B (push-pull, efficient), AB (compromise), C (RF, non-linear).Oscillators: Convert DC to AC (sine, square, sawtooth). Need positive feedback, loop gain ≥ 1, phase shift = 0° or 360°.Types: LC (tank circuit), Hartley (inductor tapped), Colpitts (capacitor tapped), Crystal (very stable), RC phase shift.Filters: Low-pass (pass bass), High-pass (pass treble), Band-pass (pass a range), Band-stop (notch).Operational Amplifier (Op-Amp): High-gain DC amp. Configurations: Inverting, Non-inverting, Summing, Integrator, Differentiator.
Mnemonic: "A for Audio, B for Better efficiency, C for Carrier (RF), AB for All-round Best."Filters: "BASS" = LOW pass, "TREBLE" = HIGH pass.
Chapter IV: Communication Systems
Key Points
Modulation: Superimpose audio (AF) on high-frequency carrier (RF) for transmission.Types: AM (amplitude varies), FM (frequency varies), PM (phase varies), SSB (single sideband).Superheterodyne Receiver: Converts incoming RF to fixed IF for easier filtering/amplification. Stages: RF amp → Mixer (with LO) → IF amp → Detector → Audio amp → Speaker.Receiver Characteristics: Sensitivity (weak signals), Selectivity (separate stations), Stability (stay on frequency), Fidelity (faithful reproduction), SNR (signal-to-noise ratio).Emission Classification: ITU codes (e.g., A3E for AM telephony, F3E for FM telephony, J3E for SSB).
Chapter V: Propagation of Electromagnetic Waves
Key Points
Propagation Modes: Ground wave (up to ~1 MHz), Sky wave (HF, ionospheric reflection), Space wave (VHF/UHF, line-of-sight).Ionosphere Layers: D (50–90 km), E (90–140 km), F1 (140–210 km), F2 (>210 km). F2 most important for HF sky wave.Skip Distance & Skip Zone: Skip distance = shortest distance skywave returns; skip zone = no signal between ground and skywave.Frequency Bands: HF (3–30 MHz, sky wave), VHF (30–300 MHz, space wave), UHF (300–3000 MHz, space wave).Critical Frequency: Highest frequency reflected vertically by ionosphere.Maximum Usable Frequency (MUF): Highest frequency for communication between two points via skywave.
Chapter VI: Fundamentals of Antennas
Key Points
Antenna: Converts RF to electromagnetic waves (transmit) and vice versa (receive).Types: Dipole (λ/2, omnidirectional), Yagi (directional, high gain), Log-periodic (wide frequency range), Collinear (stacked dipoles, higher gain).Parameters: Frequency, wavelength (λ = c/f ), impedance (typically 50 Ω), VSWR (ideal 1:1), gain (dBi/dBd), bandwidth, radiation pattern, polarization (vertical/horizontal/circular).Balanced vs Unbalanced Lines: Balanced (twin lead), Unbalanced (coax). Balun converts between.S-Meter: Indicates received signal strength (S1–S9, each 6 dB; S9+20 = 20 dB above S9).
Mnemonic: "Yagi = Yell And Get It" — it’s directional, high gain, and common for VHF/UHF.
Copyright © VU2JXM and specifc owners of material; with courtesy of IIH study material made using Perplexity AI.
