You may have seen it in the user manual of your radio‚ in a radio advertisement‚ or talked about in an online forum. I’m talking about cross-band repeating. But what is it- how does it work- and most importantly- how can you use it. I’ll talk about this somewhat misunderstood radio feature- so let dig in.
Simply put, cross-band repeating is an effective way to extend the range of your handheld radio. The cross-band repeat function works by using using a dual band mobile or base radio to retransmit on one frequency band a signal received on another frequency band, and vice versa. A common use of the cross band repeat is to extend your range of a handheld radio by using the higher power of your dual band mobile transceiver to hit a distant repeater.
I think the best way to explain how it works is to use a practical example. Say you are volunteering for a public service event and you are stationed out in a remote location. You can reach the event repeater from the mobile radio in your vehicle but the handheld radio won’t hit it. That would be ok if you are always at your car‚ but your tasks take you away from the mobile radio so you either can’t always hear it or don’t want to have to run back to the car every time you need to make a transmission.
There is a big difference between full duplex repeaters and cross band repeating. Normally a repeater is a one to many type transmission- you transmit on the repeaters input and it simultaneously retransmits on the output. Everyone hears the transmission. With cross band repeating‚ you still are transmitting on a repeater
Pretty slick. So what do you need to cross band repeat? Not every radio has that capability so the first order of business is a dual band mobile radio with dual VFOs. Some examples of radios with that capability are the Yaesu FTM-400‚ Kenwood TM-V71A‚ and Icom ID-5100A. All of these are dual band dual VFO transceivers- a transceiver with the dual watch function isn’t enough as it still only has one VFO. There are other radios that offer the cross band capability‚ so check your user manual to see if yours has dual VFOs and if it supports a cross band repeat feature.
With cross band repeat- you can pick a simplex channel on your radio and every time your mobile hears a transmission from the repeater‚ it will retransmit it on your simplex frequency. When you transmit on your simplex frequency the mobile will retransmit the communication onto the repeater frequency.
So what do you pick as the simplex cross band frequency. First off‚ you don’t want to interfere with others and you don’t want other traffic to interfere with you. So don’t choose one of the UHF calling channels. I think the safest is to use a frequency that is designated for cross band or auxiliary use. To find that frequency‚ go to your state or region’s repeater coordinating body and look at their band plan. In it you will find a list of suitable frequencies.
For this video I’m going to demonstrate the cross band function on the Yaesu FTM-400XDR. The first step is to select the frequencies- choose VHF repeater frequency on the A band and your cross band frequency on the B band. The frequencies can be programmed into memory channels or you can set them up in the radio’s VFO. Make sure that tone encode and decode is enabled on both to reduce the chance of interference opening up the cross band link. Your handheld radio will also need the UHF simplex frequency programmed into it.
To enable cross band repeat, turn the radio off. Next disconnect the microphone. The Yaesu has a hot mic when it cross bands. While holding down the GM, F and DISP buttons, press the Power button momentarily to power up the radio. Release the GM, F and DISP buttons after you see the Yaesu logo on the display. The display should indicate that your radio is now in cross band repeat mode. To disable cross band repeat, turn the radio off, then repeat the process of holding down the GM, F and DISP buttons while powering the radio on. The display should no longer indicate that the radio is in cross band repeat mode.
Now that you are in cross band repeat mode‚ you’ll transmit on your simplex frequency as you normally do. The cross band radio will retransmit it onto the repeater’s input frequency. When you lift up on the push to talk the cross band radio will then transmit the repeaters output back to you via simplex. But all this switching and retransmitting causes a bit of a delay‚ so before you speak you will need to wait about a second for all the links to activate. When you are monitoring and wish to make a transmission you will need to wait for the signal to totally drop on your UHF side before you transmit. You’ll hear what I like to call the double kerchunk‚ first the repeater dropping and then the UHF link drop. So don’t be fast on the microphone- give plenty of time for all the links to activate and deactivate.
Now heres a couple of warnings about cross band repeating. First off- don’t try to cross band two repeaters together. The squelch tail and hang time on the repeaters will cause an endless loop in the cross band‚ locking up both repeaters until your disconnect the power on your transceiver.
Second- keep the power on your cross-band transceiver at the lowest level necessary to maintain communication. Most radios aren’t designed for 100% duty cycle and constant use of the cross-band can cause your rig to get quite warm. Keep the power low, and give it a rest when necessary. (If you’re using your mobile rig in the car, you may want to use an external battery so you can still start your car)
And Finally‚ there are a couple of legal issues concerning cross band repeating. Your cross band repeat transceiver is an auxiliary station and you are controlling it via remote control. So first off you will need some method to disable the station if it fails. If you are near the radio- such as using the cross band repeat from your car while you are roaming- you would be close enough to shut it off if need be. The second option is to enable the time out timer on the radio. This will kill the transmissions if they exceed 3 minutes.
The second issue is that Since you are unable to identify that transmission yourself (its the output of the repeater being sent to your handheld) this could be considered an unidentified transmission. To be completely legal in that regard you will need some type of automatic identification system. The Kenwood TM-D10 and V71A both have that capability‚ but unfortunately other models of radios don’t. I’m not advocating that you break the FCC rules‚ but history has shown that the FCC will turn a blind eye to cross band repeat as long as you don cause harmful interference so it is up to you on how and when you wish to use the cross band feature. I’m sure if you keep the transmit power low and use it on an itinerant basis- you be fine
So what are your experiences with cross-band repeating? Leave a comment below, I’ll filter through them and keep the conversation going. Maybe one will even show up on the next your questions answered video.