Ham Radio General cheat sheet

General class licensees may use all amateur bands above 30 MHz, plus the 80, 40, 20, 15, and 10 meter HF bands with certain sub-band restrictions.

On 80, 40, and 15 meters, General class phone privileges are limited to specific sub-bands (e.g., 3.800–4.000 MHz on 80m, 7.175–7.300 MHz on 40m, 21.275–21.450 MHz on 15m).

On 20 meters, General class operators may use phone in the 14.225–14.350 MHz segment; on 10 meters, phone is allowed 28.300–29.700 MHz.

The FCC requires identification at the beginning and end of each communication and at least every 10 minutes during a contact.

Third-party traffic is permitted with countries that have signed a third-party agreement with the U.S.; otherwise, only messages of a technical nature or emergency-related may be passed.

Amateur stations must not cause interference to and must accept interference from government and commercial stations on shared bands.

Maximum transmitter power is 1,500 watts PEP output; lower limits apply on certain bands (e.g., 200 watts on 30m).

Control operator responsibilities: the control operator must be at the control point and is responsible for the proper operation of the station.

Use "CQ" followed by your call sign to initiate a general call; respond to a CQ by transmitting your call sign only.

When calling a specific station, transmit the other station's call sign followed by your own call sign.

Use ITU phonetic alphabet (Alpha, Bravo, Charlie...) for clarity; avoid words that sound like call sign letters.

In a roundtable or net, transmit only when invited or when you have emergency traffic; use "break" or "break break" for priority.

RST system: Readability (1-5), Strength (1-9), Tone (1-9); tone is only used for CW, not phone.

For a distress call, use "MAYDAY" repeated three times followed by your call sign and location; for urgency, use "PAN PAN".

When operating split (transmit and receive on different frequencies), listen on the DX station's transmit frequency and call on the announced frequency.

Logging is not required by FCC for General class, but is good practice; some contests require logs.

The ionosphere consists of D, E, F1, and F2 layers; F2 layer is primarily responsible for long-distance HF propagation.

Maximum Usable Frequency (MUF) is the highest frequency that will be reflected by the ionosphere between two points at a given time.

The critical frequency is the highest frequency reflected vertically from the ionosphere; MUF = critical frequency / cos(theta) for oblique incidence.

Sporadic E propagation occurs when dense patches of ionization form in the E layer, allowing VHF contacts over 1,000 miles.

Tropospheric ducting occurs when temperature inversions cause VHF/UHF signals to bend and travel beyond the horizon.

Ground wave propagation is most effective on lower frequencies (160m, 80m) and follows the Earth's curvature.

The 10-meter band supports worldwide communication during high sunspot activity (high solar flux) via F2 layer.

Skip zone is the area between the end of ground wave coverage and the first returning skywave signal; it can be filled by NVIS on lower bands.

Use a dummy load for testing transmitters to avoid interference; it should present a 50-ohm impedance.

An SWR meter measures the ratio of forward to reflected power; an SWR of 1:1 is ideal, and above 2:1 may indicate a problem.

When using a linear amplifier, ensure it is properly tuned and that the drive power does not exceed the amplifier's ratings.

Use a speech processor to increase average power on SSB, but avoid over-processing which can cause distortion and splatter.

Set the AGC (Automatic Gain Control) to fast for CW and SSB, slow for AM; AGC prevents receiver overload on strong signals.

Use the RIT (Receiver Incremental Tuning) to fine-tune a received signal without changing your transmit frequency.

When operating mobile, use a properly fused power connection directly to the battery to reduce noise and voltage drop.

For digital modes, adjust audio drive so the ALC meter shows little or no deflection to avoid distortion.

Ohm's Law: E = I × R; I = E / R; R = E / I.

Power: P = E × I; P = I² × R; P = E² / R.

Series resistance: R_total = R1 + R2 + ...; parallel resistance: 1/R_total = 1/R1 + 1/R2 + ...

Capacitive reactance: Xc = 1 / (2πfC); inductive reactance: Xl = 2πfL.

Impedance in series: Z = √(R² + (Xl - Xc)²); phase angle = arctan((Xl - Xc)/R).

Resonance occurs when Xl = Xc, so f = 1 / (2π√(LC)).

Peak-to-peak voltage = 2.828 × RMS voltage for a sine wave; RMS = 0.707 × peak.

Conductance is the reciprocal of resistance: G = 1/R, measured in siemens.

Resistor color code: Black=0, Brown=1, Red=2, Orange=3, Yellow=4, Green=5, Blue=6, Violet=7, Gray=8, White=9; Gold=±5%, Silver=±10%.

Capacitors store energy in an electric field; types include ceramic (stable, low capacitance), electrolytic (polarized, high capacitance), and tantalum.

Inductors store energy in a magnetic field; inductance increases with more turns, larger core area, and higher permeability.

Diodes allow current in one direction; a silicon diode has a forward voltage drop of about 0.7V.

Transistors: bipolar junction transistors (BJT) have NPN or PNP polarity; field-effect transistors (FET) are voltage-controlled.

Transformers can step up or down AC voltage; turns ratio equals voltage ratio; impedance ratio equals square of turns ratio.

Potentiometers are variable resistors with three terminals; rheostats are two-terminal variable resistors.

Fuses protect circuits by melting when current exceeds rating; they are rated in amperes and voltage.

A half-wave rectifier uses one diode and produces pulsating DC at the input frequency; a full-wave bridge uses four diodes and doubles the ripple frequency.

A pi-network filter in a power supply reduces ripple; it consists of a capacitor, inductor, and capacitor.

Voltage regulators (e.g., 7805, 7812) maintain a constant output voltage; they require input voltage at least 2V above output.

An oscillator generates a signal; a Colpitts oscillator uses a tapped capacitor divider, and a Hartley uses a tapped inductor.

A mixer combines two signals to produce sum and difference frequencies; used in receivers for frequency conversion.

A class C amplifier is used for FM and CW because it is highly efficient but distorts the signal; class AB is used for SSB.

A dip meter measures resonant frequency of a tuned circuit by detecting a dip in current.

An SWR bridge uses a directional coupler to sample forward and reflected power.

Bandwidth of an FM signal is approximately 2 × (peak deviation + modulating frequency) by Carson's rule.

SSB (J3E) transmits one sideband and suppresses the carrier, reducing bandwidth to about 3 kHz.

CW (A1A) is on-off keyed continuous wave; bandwidth is typically less than 500 Hz.

Frequency modulation (F3E) has constant amplitude; amplitude modulation (A3E) varies amplitude.

Digital modes like FT8 use 8-FSK modulation with 50 Hz bandwidth; PSK31 uses phase shift keying with 31 baud.

The duty cycle affects average power: for CW it is 100% during key-down, for SSB it is lower, allowing higher PEP.

Splatter is caused by overmodulation or nonlinear amplification, producing unwanted sidebands.

The emission designator includes necessary bandwidth, modulation type, and nature of signal (e.g., 2K80J3E).

Half-wave dipole length in feet = 468 / frequency (MHz); quarter-wave vertical length = 234 / frequency (MHz).

Feed line impedance: coaxial cable commonly 50 ohms; ladder line 300–600 ohms; matching to antenna is important for low SWR.

Velocity factor of coaxial cable reduces physical length: physical length = electrical length × velocity factor.

SWR = (1 + √(Pr/Pf)) / (1 - √(Pr/Pf)) where Pr is reflected power and Pf is forward power.

A balun converts between balanced and unbalanced lines; a 1:1 balun is used for dipoles fed with coax.

Antenna gain is expressed in dBi (relative to isotropic) or dBd (relative to dipole); dBd = dBi - 2.15.

A Yagi antenna has a driven element, reflector, and directors; gain increases with more directors.

Feed line loss increases with frequency and length; use low-loss cable for VHF/UHF.

RF exposure limits are based on frequency and power density; the FCC requires evaluation of stations to ensure compliance.

Never look into an open waveguide or antenna feed while transmitting; RF can cause eye damage.

Use proper grounding: connect equipment to a common ground bus and to earth ground via a ground rod.

High voltage in amplifiers can be lethal; discharge capacitors before servicing.

Antennas must be installed so they cannot contact power lines; minimum safe distance is 10 feet from power lines.

Use a GFCI (Ground Fault Circuit Interrupter) for outdoor electrical outlets.

Battery safety: lead-acid batteries produce hydrogen gas; charge in a ventilated area; avoid short circuits.

Lightning protection: use a lightning arrestor on feed lines and disconnect antennas when not in use.