CB Radio

Technical Specifications

CB radio operates in the 11-meter band with 40 channels spaced at 10 kHz intervals. The band spans 26.965 MHz to 27.405 MHz—a relatively narrow slice of spectrum that became the most popular two-way radio service in history.

┌─────────────────────────────────────────────────────────────┐
│              CB RADIO TECHNICAL SPECIFICATIONS              │
├─────────────────────────────────────────────────────────────┤
│  Frequency Range:   26.965 - 27.405 MHz (11-meter band)    │
│  Channels:          40                                      │
│  Channel Spacing:   10 kHz                                  │
│  Bandwidth:         8 kHz (AM/FM), 3 kHz (SSB)             │
├─────────────────────────────────────────────────────────────┤
│  MODULATION MODES (FCC Authorized):                         │
│  ─────────────────────────────────────────────────────────  │
│  AM (A3E):          4 W carrier max                         │
│  FM (G3E):          4 W carrier max (authorized 2022)       │
│  SSB (J3E):         12 W PEP max                            │
├─────────────────────────────────────────────────────────────┤
│  ANTENNA (quarter-wave vertical at 27 MHz):                 │
│  ─────────────────────────────────────────────────────────  │
│  Length:            2750 / f(MHz) = ~102 inches = 8.5 ft    │
│  Half-wave dipole:  492 / f(MHz) = ~216 inches = 18 ft     │
│  Ground plane:      3-4 radials at 45°                     │
├─────────────────────────────────────────────────────────────┤
│  PERFORMANCE:                                               │
│  ─────────────────────────────────────────────────────────  │
│  Range (AM):        2-10 miles typical                      │
│  Range (SSB):       5-20 miles typical                      │
│  Range (skip):      50-300+ miles (ionospheric)            │
│  Ground wave:       Up to 20 miles under ideal conditions   │
└─────────────────────────────────────────────────────────────┘

All 40 CB Channels

Channels are NOT in sequential frequency order. The FCC assigned frequencies with gaps and non-sequential ordering. Some channels have conventional usage by operators, though these are informal conventions, not legal requirements.

Ch  Freq (MHz)   Use / Designation
─── ──────────── ───────────────────────────────────
 1   26.965     General
 2   26.975     General
 3   26.985     General
 4   27.005     General
 5   27.015     General
 6   27.025     Trucker traffic
 7   27.035     General
 8   27.055     General
 9   27.065     ★ EMERGENCY ONLY ★
10   27.075     Truckers weigh station
11   27.085     Calling channel (AM)
12   27.105     General
13   27.115     Marine / RV
14   27.125     Walkie-talkies (FRS/GMRS)
15   27.135     AM calling
16   27.155     SSB
17   27.165     North/South truckers
18   27.175     General
19   27.185     ★ EAST/WEST TRUCKERS (most popular)
20   27.205     General
21   27.215     General
22   27.225     General
23   27.255     General
24   27.235     General
25   27.245     General
26   27.265     General
27   27.275     General
28   27.285     General
29   27.295     General
30   27.305     General
31   27.315     General
32   27.325     General
33   27.335     General
34   27.345     General
35   27.355     SSB calling
36   27.365     SSB
37   27.375     SSB
38   27.385     ★ LSB CALLING (most popular SSB)
39   27.395     LSB
40   27.405     SSB

NOTE: Channels 36-40 are SSB-preferred. Channels 1-35
support AM; FM added in 2022 on all 40 channels.

CB Frequency Calculation

The base frequency is 26.965 MHz for Channel 1, with 10 kHz spacing—but the channel-to-frequency mapping has deliberate gaps and non-sequential ordering.

Frequency Formula (approximate):
─────────────────────────────────────────────────────────────
  f(N) = 26.965 + (N-1) × 0.010 MHz   (where N = channel)

  However, this is APPROXIMATE. Actual FCC frequencies have gaps:

  Ch 1-5:    26.965, 26.975, 26.985, 27.005, 27.015
             (gap at 26.995 — skipped!)
  Ch 6-10:   27.025, 27.035, 27.055, 27.065, 27.075
             (gap at 27.045 — skipped!)
  Ch 11-15:  27.085, 27.105, 27.115, 27.125, 27.135
             (gap at 27.095 — skipped!)
  Ch 16-20:  27.155, 27.165, 27.175, 27.185, 27.205
             (gaps at 27.145, 27.195 — skipped!)
  Ch 21-25:  27.215, 27.225, 27.255, 27.235, 27.245
             (out of order! Ch23 > Ch24 > Ch25 in frequency)
  Ch 26-30:  27.265, 27.275, 27.285, 27.295, 27.305
  Ch 31-35:  27.315, 27.325, 27.335, 27.345, 27.355
  Ch 36-40:  27.365, 27.375, 27.385, 27.395, 27.405

Total band occupancy: 26.965 to 27.405 = 440 kHz
Total channels: 40 × 10 kHz = 400 kHz used
Gaps: 40 kHz reserved (for future use, now abandoned)
─────────────────────────────────────────────────────────────

Channel Usage by Country

CB regulations vary significantly worldwide. The US 40-channel plan is the most widely adopted, but regional variations exist.

United States

US CB Channel Usage (47 CFR Part 95 Subpart D):
─────────────────────────────────────────────────
  Ch 1-35:    AM (A3E) — 4W carrier max
              FM (G3E) — 4W carrier max (since 2022)
  Ch 36-40:   SSB (J3E) — 12W PEP max
              LSB (Lower Sideband) preferred on 38-40
  Ch 9:       Emergency and roadside assistance ONLY
  Ch 19:      Highway/trucker information (unofficial)
  Ch 11:      Calling channel — establish contact, QSY
─────────────────────────────────────────────────
  No license required since April 28, 1983
  FCC type-accepted equipment required
  Power modifications illegal

United Kingdom

UK CB Radio:
─────────────────────────────────────────────────
  Standard 40 channels: Same as US (CEPT plan)
  Additional FM band:   27.60125 - 27.99125 MHz
                        (40 extra FM channels)
  Total:                80 channels available
  Modes:                AM, FM, SSB all legal
  Power:                4W AM/FM, 12W PEP SSB
  License:              License-free since Nov 2006
─────────────────────────────────────────────────

Europe (CEPT)

CEPT Countries (most EU nations):
─────────────────────────────────────────────────
  Standard:    40 channels (same frequencies as US)
  Modes:       FM dominant (AM less common)
  Power:       4W AM/FM, 12W PEP SSB
  License:     License-free in most countries
─────────────────────────────────────────────────

Germany

Germany — Extended CB allocation:
─────────────────────────────────────────────────
  Ch 1-40:     Standard CEPT channels
  Ch 41-80:    Additional German CB channels
               (27.415 - 27.805 MHz)
  Ch 52:       Digital mode allocation
  Ch 53:       Digital mode allocation
  Ch 76:       Digital mode allocation
  Ch 77:       Digital mode allocation
  Modes:       AM, FM, SSB, digital (on 52/53/76/77)
  Power:       4W AM/FM, 12W PEP SSB
  License:     License-free since 2018
─────────────────────────────────────────────────

SSB Operation

Single Sideband (SSB) is the most efficient mode for long-distance CB communication. By suppressing the carrier and one sideband, all transmitter power concentrates into a single sideband, providing 2-3x the range of AM at the same power level.

USB vs LSB

Sideband Selection:
─────────────────────────────────────────────────
  USB (Upper Sideband):
    - Default for HF amateur radio
    - Used on CB Ch 36-37
    - Carrier + upper sideband → suppressed carrier + USB

  LSB (Lower Sideband):
    - Traditional CB SSB preference
    - Used on CB Ch 38-40
    - Ch 38 is the de facto SSB calling frequency
    - Carrier + lower sideband → LSB + suppressed carrier

  WHY LSB ON CB?
    Historical convention from early SSB equipment.
    Ch 38 LSB is universally recognized as CB SSB calling.
─────────────────────────────────────────────────

SSB Advantages

• Power efficiency: 12W PEP SSB ≈ 36W equivalent AM output
• Bandwidth: 3 kHz vs 6-8 kHz for AM — less interference
• Range: 2-3x AM range at equivalent power
• Reduced QRM: Narrower bandwidth = fewer adjacent channel QRM

SSB Tuning

SSB requires precise frequency alignment. The BFO (Beat Frequency Oscillator) must be set to within ±50 Hz of the transmitted carrier frequency. When tuning in an SSB signal on AM, voices sound like "Donald Duck" until properly aligned.

SSB Operating Tips:
─────────────────────────────────────────────────
  1. Start on AM, establish contact
  2. Agree on SSB channel and sideband
  3. Switch to SSB mode
  4. Fine-tune clarifier/RIT until voice sounds natural
  5. USB for Ch 36-37, LSB for Ch 38-40
  6. Keep transmissions short — SSB is less tolerant
     of frequency drift than AM
─────────────────────────────────────────────────

Antenna Design

At 27 MHz, antenna dimensions become practical for home construction. The quarter-wave vertical is the most common CB antenna, used in mobiles, base stations, and portables.

Quarter-Wave Vertical

Quarter-Wave Vertical Antenna:
─────────────────────────────────────────────────
  Formula:  L = 2750 / f(MHz)
  At 27 MHz: L = 2750 / 27 = 101.9 inches
             L ≈ 102 inches = 8.5 feet = 2.6 meters

  Components:
    - Radiator:  ~8.5 ft vertical element
    - Radials:   3-4 ground radials at 45° downward
    - Feedpoint: Center of base, 50Ω coax feed
    - Matching:  Radial angles provide impedance match

  SWR Target:  < 1.5:1 across desired channels
  Bandwidth:   ~2 MHz at SWR < 2:1 (covers all 40 ch)
─────────────────────────────────────────────────

Half-Wave Dipole

Half-Wave Dipole:
─────────────────────────────────────────────────
  Formula:  L = 492 / f(MHz)
  At 27 MHz: L = 492 / 27 = 18.2 feet
             L ≈ 18 feet = 5.5 meters (total)

  Each arm:  9.1 feet from center feedpoint
  Feed:      50-75Ω coax (RG-58, RG-8X, or RG-213)
  Pattern:   Donut-shaped, horizontal polarization

  Advantage: Higher gain than quarter-wave (2.15 dBi)
  Best for:  Base station, horizontal mounting
─────────────────────────────────────────────────

Coaxial Cable

CB Coax Options:
─────────────────────────────────────────────────
  RG-58:    50Ω, thin (0.195"), lossy at 27 MHz
            Loss: ~3.3 dB per 100ft at 27 MHz
            Use: Short runs only (< 50ft)

  RG-8X:    50Ω, medium (0.242"), low loss
            Loss: ~2.0 dB per 100ft at 27 MHz
            Use: Best balance of loss vs. flexibility

  RG-213:   50Ω, thick (0.405"), very low loss
            Loss: ~1.4 dB per 100ft at 27 MHz
            Use: Base stations, long runs

  RG-6:     75Ω — NOT recommended (impedance mismatch)
            Requires 4:1 balun if used

  PL-259/SO-239 connectors: Standard CB UHF connector
  N-type:  Superior, weather-resistant (rare on CB)
─────────────────────────────────────────────────

Ground Plane Antenna

The ground plane is the most practical base station CB antenna. A vertical radiator fed against 3-4 radials angled downward at 45° provides an excellent match to 50Ω coax and good low-angle radiation for DX contacts.

Legal Limits (US - Part 95)

US CB Legal Requirements (47 CFR Part 95, Subpart D):
══════════════════════════════════════════════════════════════
  LICENSE:          Not required since April 28, 1983
  EQUIPMENT:        FCC type-accepted/certified only
  FREQUENCY:        26.965 - 27.405 MHz only

  POWER LIMITS:
    AM (A3E):       4 watts carrier maximum
    FM (G3E):       4 watts carrier maximum (2022+)
    SSB (J3E):      12 watts peak envelope power (PEP)

  PROHIBITED:
    × No external power amplifiers
    × No modifications exceeding type-accepted specs
    × No encryption or scrambling
    × No data transmission (limited exceptions)
    × No retransmission of broadcast signals
    × Channel 9: Emergency use only

  FCC ENFORCEMENT:
    First offense:    Warning or $10,000+ fine
    Repeat offense:   Equipment seizure, criminal penalties
    Jamming:          Federal crime (up to $100,000 fine)
══════════════════════════════════════════════════════════════

Operating Techniques

CB Lingo (10-Codes)

Common CB 10-Codes:
─────────────────────────────────────────────────
  10-1    Poor reception
  10-2    Good reception
  10-3    Stop transmitting
  10-4    Acknowledgment / OK
  10-5    Relay message
  10-6    Busy
  10-7    Out of service
  10-8    In service
  10-9    Repeat message
  10-10   Off the air
  10-12   Standby
  10-13   Advise weather
  10-20   Location ("What's your 10-20?")
  10-33   Emergency
  10-36   Correct time
  10-37   Wrecker/ tow truck needed
  10-39   Urgent — use caution
  10-40   No escort needed
  10-45   All units within range
  10-50   Break channel
  10-60   Channel 19
  10-62   Cannot copy
  10-63   Net directed to
  10-64   Message for...
  10-65   Net frequency
  10-70   Fire
  10-71   Proceed with caution
  10-77   Negative
  10-80   Highway patrol
  10-84   My address is...
  10-85   My address is...
  10-91   Talk on the side
  10-92   Your transmitter is out of tune
  10-94   Give me a long count
  10-96   Breaker one-nine (Channel 19 call)
  10-99   Wanted / Stolen
─────────────────────────────────────────────────

Call Signs and Handles

CB radio does not use formal call signs like amateur radio. Instead, operators adopt "handles"—pseudonyms that became a distinctive part of CB culture. Popular handles reference trucks, geography, or personal traits. Some operators use numbers (e.g., "Rubber Duck" or "Snowman").

Skip and DX

CB signals can propagate hundreds or thousands of miles via ionospheric skip, especially during solar maximum. This phenomenon, called "skip," allows worldwide communication but creates channel congestion. During skip conditions, Ch 19 and SSB channels can become extremely crowded.

• Ground wave: 5-20 miles, consistent, terrain-dependent
• Skip: 50-300+ miles, sporadic, solar-cycle dependent
• Sporadic-E: 500-1500 miles, summer months, 50 MHz+ primarily
• Solar maximum: Enhanced skip, worldwide contacts possible

The Decline and Modern Revival

Cell phones, the internet, and FRS/GMRS radios eroded CB's dominance from the 1990s onward. However, CB has experienced a significant revival since the 2010s:

• Truckers: Still widely used; Ch 19 remains active coast-to-coast
• Off-roaders: Jeeps, 4x4s, and overlanders for trail communication
• Preppers: Independent communication when infrastructure fails
• DX hobbyists: Long-distance skip contacts and contesting
• Vintage collectors: Restoring and operating classic Cobra, Midland radios
• Farmers/rural: Quick communication across property without licensing

CB vs. Other Services

Comparison:
─────────────────────────────────────────────────
  Service      License    Channels  Power    Freq
  ─────────────────────────────────────────────
  CB           No         40        4W       27 MHz
  FRS          No         22        2W       462 MHz
  GMRS         Yes        16        5W       462 MHz
  MURS         No         5         2W       151 MHz
  Amateur      Yes        Hundreds  1.5kW+   All
  Marine VHF   No*        57        25W      156 MHz
─────────────────────────────────────────────────
  * Marine VHF requires Ship Station License for
    vessels >65ft or for commercial use