Cross Band Repeat (CBR)

Note: This presentation was given last year at our club meeting. We have several good programs at club meetings on a variety of topics. If you haven’t been to a club meeting in awhile to hear some our programs, you are missing out on a great information resource.

As Amateur Radio operators, we are often in situations where we are involved in event or emergency communications where we need to be on a handheld transceiver (HT). However, depending on location and circumstance, we may not able to communicate with fellow ham operators either via simplex between HTs or from our HT with one of the local repeaters. Another situation may be that some people may be on one band, but not all people can be on that band. This is where cross-band repeat (CBR) with a mobile VHF/UHF rig comes in handy.

What Exactly is CBR?

  • Use of a dual-band, two-sided mobile radio with CBR capability to repeat TXs to/from adjacent HTs and regular repeater or other HTs on another band
  • Can involve a regular repeater or Simplex HTs on different bands
  • Can be UHF to VHF or VHF to UHF
  • Can be half-duplex or full-duplex
  • Half-duplex requires a dual-band, simultaneous RX HT

When Is It Useful?

  • Operating in a remote location with HTs and HTs are out of regular repeater range, but mobile rig is within range
  • Operating using an HT in a location that you do not have or cannot setup a mobile rig (another part of your house, a restaurant, or office building)
  • Operating in a group using HTs outside of normal repeater range (search/rescue, disaster, emergency)
  • Having group remote simplex HT operations on UHF band and some HTs are single-band VHF only (reverse is also true)

Scenario Diagrams

Full Duplex

  • Can use a dual-band or single-band HT
  • Single-band radios obviously limited to their band
  • HT TX and RX to CBR mobile using simplex on HT main band
  • Leaves HT sub-band open for monitoring other frequencies
  • CBR mobile TX BOTH HT and regular repeater TXs

Half-Duplex

  • Requires a dual-band HT with simultaneous RX
  • HT transmits to CBR mobile using simplex on its CBR frequency on HT main band
  • HT monitors regular repeater on its output frequency on HT sub-band
  • CBR mobile only retransmits HT TXs

Simplex

  • Can use dual-band or single-band HTs
  • All HTs are simplex and should be setup for full-duplex operation to account for single-band HTs
  • Mobile CBR setup for two-way full-duplex CBR operation

Do’s and Don’t’s

  • Do be aware of CBR mobile duty cycle
  • Do check with repeater trustee when involving a regular repeater
  • Do ID regularly and CBR mobile control operator must be nearby
  • Do not attempt in-band repeat on CBR mobile
  • Do not use National Simplex Call frequencies
    • VHF: 146.520 or UHF: 446.000
  • Do use CBR simplex range (UHF) or unused simplex (VHF) in Band Plan
    • UHF CBR simplex range: 445.750 – 445.975
    • VHF simplex ranges: 145.500-145.800, 146.400-146.440, 146.500-146.600, 147.400-147.440, and 147.500-147.600

Demonstration Videos

Yaesu FT-8900 and Yaesu VX-7

Kenwood TM-D710 and Yaesu VX-7


 

 

 

 

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