Friday, February 19, 2016

Crossband Repeater Function – Reducing Duty Cycle

One of the first things that I did when I received my multi-band mobile radio was to set it up to repeat a local 2m repeater to an unused 70cm channel so I could listen and talk from an HT from inside my home. 

This worked well, but I started to be concerned with the amount of time my radio was transmitting – albeit on low power – and frustrated with repeaters that had a longer squelch tail. I found myself unable to transmit, even though the conversation had paused, because my mobile radio was still transmitting the tail to the 70cm channel. 

Below are the general instructions on how I overcame theses issues.


  • This works when the repeater is strong enough for the HT to receive on its own.
  • This can have issues if others transmitting to the same repeater are close enough to be received by your mobile radio.
  • In this example I am contacting a 2m repeater and therefore using a 70cm frequency to communicate between the HT and my crossband repeater.
  • I used CHIRP software to configure my HT.
  • Not all HT's that I have tested can split between bands on a channel as described below. I have tested this successfully with Baofeng, Wouxon, Anytone, and Yaesu.

The Crossband Repeater

Figure 1

Step 1: Configure one side of the radio in SIMPLEX mode to transmit on the INPUT frequency of the repeater, complete with required tone. (note this is a 2m freq)

Step 2: Configure the second side of the radio in SIMPLEX mode to transmit on an unused frequency on the alternate band.

Step 3: Set your radio for crossband repeat. 

Some radios, such as my Wouxon UV-950P and Kenwood TM-V71a (above) can be set to repeat in only one direction. If your radio supports this, set it so that it only takes communications from the HT channel and repeats it to the 2m Repeater channel. This will eliminate issues caused by other transmissions into the repeater being picked up and retransmitted unnecessarily.

The HT and CHIRP

Figure 2

This setup will allow your HT to listen to the repeater directly, but transmit your output through your own Crossband repeater, thus reducing your radio’s duty cycle and eliminating issues with long squelch tails.

Step 1: Set the frequency for the OUTPUT of the repeater; your HT will be receiving the repeater’s output directly rather than from your own crossband repeater.

Step 2: Set the TONE for the 70cm frequency your using (in Crossband Repeater, Step 2) if applicable.

Step 3: Set the Duplex to SPLIT

Step 4: Set the Offset to the frequency of the 70cm channel you will be using (Crossband Repeater, Step 2)

Note: not all HT's can split between bands on a channel. I have used this technique with Baofengs, Wouxons, Anytones, and Yaesu radios.

If your HT does not allow the split, but can monitor two channels, simple set one channel to the repeater and the other to the 70cm frequency, and make sure when you key up that you are transmitting on the 70cm side.

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