Ham Radio Technician flashcards

31 cards. Read the term and the definition here. The deck at the top of this page is optional.

Part 97 purpose

The FCC rule part governing the Amateur Radio Service. It defines the service as voluntary, noncommercial, and devoted to self-training, intercommunication, and technical investigation, with no pecuniary interest.

License term and renewal

An amateur license is valid for 10 years. Renewal may be filed within 90 days before expiration; after expiration a two-year grace period allows renewal, but transmitting is not allowed until the renewed license is granted.

Technician HF privileges

Technicians may use CW and data on the 80, 40, and 15 meter bands, limited to the Novice-class subbands. All amateur bands above 30 MHz are also available, with 1500 W PEP maximum output.

Station identification requirement

Transmit your FCC-assigned call sign at the start and end of each communication and at least every 10 minutes during it. Identification may be by voice, CW, or digital mode.

Third-party communication rule

A message sent by an amateur station on behalf of a third party. It is allowed only when the third party's country has a third-party agreement with the US, and never for business purposes.

Prohibited transmission examples

Obscene or indecent language, music except incidental to authorized retransmission, commercial advertising, and communications for hire or material compensation are prohibited under Part 97.

Control operator responsibility

The control operator is responsible for the proper operation of the station. The station must have a control point, and the operator must be able to disable the transmitter if necessary.

Phonetic alphabet usage

Use standard ITU phonetics such as Alfa, Bravo, Charlie to spell call signs and unfamiliar words. This reduces errors when signals are weak or noise is high.

RST signal report

R is readability on a 1-5 scale, S is signal strength on a 1-9 scale, and T is CW tone on a 1-9 scale. Phone contacts usually exchange R and S only.

Repeater offset standards

The standard offset is 600 kHz on the 2 meter band and 5 MHz on the 70 cm band. CTCSS tones or DCS codes may be required to access the repeater.

MAYDAY emergency call

The voice distress signal, derived from the French m'aidez. During a bona fide emergency, the FCC permits operation outside normal privileges, including on any frequency needed.

Q signal meanings

QRM means man-made interference, QRN means atmospheric noise, QSB means fading, QSL means acknowledgment, QSY means change frequency, QTH means location, and QRT means stop transmitting.

Net control station role

The net control station directs all traffic on the net. Participants check in with their call sign and follow the net control's instructions, using tactical call signs only if permitted.

Ohm's Law

V equals I times R, where V is voltage in volts, I is current in amperes, and R is resistance in ohms. Rearranged, I equals V divided by R, and R equals V divided by I.

DC power formula

Power in watts equals voltage times current, P = V × I. It can also be written as P = I squared times R, or P = V squared divided by R.

Series and parallel resistance

Series resistances add directly. For parallel resistances, the reciprocals add; two resistors combine as R1 times R2 divided by R1 plus R2.

Capacitive reactance formula

Xc equals 1 divided by 2 pi f C. Capacitive reactance decreases as frequency or capacitance increases, so capacitors pass higher frequencies more easily.

Inductive reactance formula

Xl equals 2 pi f L. Inductive reactance increases with frequency and inductance, so inductors oppose higher frequencies more strongly than lower ones.

LC resonance frequency

Resonance occurs when inductive and capacitive reactance are equal. The resonant frequency is 1 divided by 2 pi times the square root of L times C.

Decibel power ratio

For power, dB equals 10 log base 10 of P2 divided by P1. A 3 dB increase doubles power, and a 10 dB increase multiplies power by ten.

Wavelength formula

Wavelength in meters equals 300 divided by frequency in MHz. A half-wave dipole is about 468 divided by frequency in MHz, measured in feet.

Ionospheric layers

The D, E, F1, and F2 layers make up the ionosphere. The F2 layer supports long-distance HF skip, while the D layer absorbs lower HF signals during daylight.

SSB modulation

Single sideband is amplitude modulation with one sideband and the carrier suppressed. It concentrates power in a narrow bandwidth and is common for HF voice communication.

SWR meaning

Standing wave ratio measures how well the antenna impedance matches the feed line. A 1:1 ratio is ideal; above 3:1 may cause a transmitter to reduce power automatically.

Balun function

A balun matches a balanced antenna, such as a dipole, to an unbalanced feed line such as coax. A 1:1 balun is commonly used with coax-fed dipoles.

Half-wave dipole impedance

A center-fed half-wave dipole has a feed-point impedance near 73 ohms in free space. It radiates horizontally polarized signals when mounted horizontally.

Yagi-Uda antenna

A directional antenna with one driven element, a reflector, and one or more directors. Adding directors increases forward gain and narrows the radiation pattern.

Coax feed line loss

Coaxial cable loss increases with frequency and length. Ladder line and open-wire feeders have lower loss but require a balanced antenna and often an antenna tuner.

Narrowband FM deviation

Narrowband FM on the 2 meter and 70 cm bands uses about plus or minus 5 kHz deviation. Wideband FM, used for broadcast, uses much greater deviation.

CTCSS tones

Continuous Tone-Coded Squelch System uses subaudible tones to access a repeater. The repeater responds only when it detects the correct tone, reducing interference.

FT8 digital mode

A weak-signal digital mode using 15-second transmit and receive cycles. It decodes signals far below noise level and is popular for HF contacts with modest stations.