Cross Band Repeat. Why??

Hi guys, I have had the Wouxun KG-UV8D now for some time and it does cross band repeat.

I know I could do some research but this is a discussion forum so I thought I'd ask the question and hopefully get an answer in laymans terms

So what can I do with it? What practical uses does it have? How do you use it?

Please don't move to entry level radio section as this is a generic post about cross band repeat

Cheers!

With a handheld, not much. But I've worked hundreds of events where I couldn't hit the main repeater, or simplex to net control with just a handheld..

Fire up the dualband mobile in the car, put one side on the event repeater or simplex freq and the other on a simplex freq and voila, my 300mw handheld becomes a 50 or 45 watt mobile...

I have used this during events (bikeathons, marathons etc) and also have used it for disaster drills at the local airport.

Cheers for the quick reply there Gene

You could connect the HT to AC power at home, or DC power in your car, add an amplifier, (and perhaps a diplexer and a gain antenna for each band), and of course coax to tie it all together.
However, with the added expense of the amplifier, you might as well buy a mobile dual-band radio with cross band repeat.

John
Peoria, AZ

If you use a good antenna and a good location there are occasions where it could be used as a makeshift temporary repeater. If you put it in a tree on the top of a hill you have a good chance of getting through if both stations have line of sight to that tree. It is by no means comparable to a real repeater, but it might make the difference between getting through or not.

When I lived in a community I would walk my dog around the neighborhood. I could hear our club 2 meter repeater just fine but had difficulty having a decent conversation using my HT with a rubber duck. I bought a dual band HT and would set up the dual band radio, in my house, to cross band repeat. I would "talk" to my base radio on UHF, it would "repeat" over to VHF and when I unkeyed I could listen to the VHF just fine. My HT was set at 500mw and would be full quieting


Your dual band radio, that's capable of cross band repeating, essentially becomes a repeater repeater. It can be set up, according to your flavor of radio, to have different ways in which to cross band repeat.
Be sure to ID each TX frequency, to be legal, if you want to experiment. Option one is, for example, that your HT transmits to your cross band radio on 446.025mhz, the cross band radio then simultaneously transmits on 147.735mhz (input to 147.135mhz) and keys up the VHF repeater. You carry on your conversation and then unkey your HT, the cross band radio will then unkey and you listen to 147.135mhz on the HT and the cross band radio is NOT transmitting. This option is easiest since ALL transmitters are ID'd.

Option two is, the HT transmits on 446.025mhz and the cross band radio simultaneously transmits on 147.735mhz and the VHF repeater transmits on 147.135mhz. When you unkey your HT the cross band radio now transmits BACK to your HT on 446.025mhz. With this option the transmission FROM the cross band radio now has to be ID'd legally. It can be done but requires more of an effort to do so.

I hope I didn't confuse you, when I first started doing it someone tried to explain it to me and I had to draw it out on paper for it to make sense to me. I haven't used cross banding in many years but I consider a useful mode.

Very good description firefighter479! Identifying for option #2 can be very difficult if your radio doesn't have an ID function built into the radio. As you said option 1 is much easier and usually you can hear the repeater directly.
BB

Agreed - nice description, Firefighter!!! Key points of cross-band repeat are that your radio is receiving on VHF and transmitting that back out on UHF and doing the same thing in reverse.

An illustration: VHF Radio <--> X-band Radio (VHF/UHF) <--> UHF Radio

The VHF and UHF radios can talk to each other even though they are on different bands.

The uses for this can be many things - a hunter may have a HT on his person and a X-Band mobile in his vehicle on a hill so he can communicate to the outside world via HT. A person may want to use a HT X-band repeated through home base antenna. I use it when off-roading to keep in touch with people out in the desert via mobile X-Band in my motorhome to my HT. Stuff like that.

X-Band is more useful with a more powerful mobile but a HT with elevation and/or good antenna can be very useful too.

You could also take two crossbandable HTs and set them up for unidirectional cross banding. One ht receives vhf and repeats at low power on uhf. The other receives uhf (same frequency the other radio is transmitting on) and transmits high power on a different vhf frequency.

Place the two HTs on rooftops, peaks, etc 100 feet or greater away, and you've just created a split site 2 m repeater.

We do something very similar (though the distance between rx and tx is measured in miles) for 6m and 10m repeaters because duplexers are extremely expensive that low in frequency.


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firefighter479 said:

...I bought a dual band HT and would set up the dual band radio, in my house, to cross band repeat. I would "talk" to my base radio on UHF, it would "repeat" over to VHF and when I unkeyed I could listen to the VHF just fine. My HT was set at 500mw and would be full quieting

Click to expand...

I used this type of setup for a bicycle event, when I was the ham assigned to be on the ambulance. I had my mobile inside the ambulance, relaying 70cm to the 2m repeater input.

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I used to used cross band repeat with a pair of Kenwood radios, and then single Kenwood dual (or tri-) band radios, and it was handy for special events and while operating away from the vehicle. The problems began when fixed repeater squelch tails were lengthened to several seconds on some machines. Because the cross band repeating radio would not transmit until the "tail" dropped. the person trying to use the cross band repeater could never or rarely access the fixed repeater without waiting for the tail to drop.

My current dual band transceiver has the capability, but I have not used it more than a couple of times, and that was with both bands set to simplex frequencies.

To properly cross band, all radios in the system must be identified. Since none of these new crossband repeat HTs have an IDer, this function becomes useless and illegal for true crossband operation.

So, KD8DVR, I thought about the same thing and you are correct - must identify at least every 10 minutes. If one were using X-band repeat without going through a repeater (regular repeater) and one were to identify by voice every 10 minutes would that not then be legal?

I use X-band on my Kenwood mobile and have my call sent via morse every 10 minutes but as you said, no way to do it on the HTs.

WyoDuner said:

So, KD8DVR, I thought about the same thing and you are correct - must identify at least every 10 minutes. If one were using X-band repeat without going through a repeater (regular repeater) and one were to identify by voice every 10 minutes would that not then be legal?

I use X-band on my Kenwood mobile and have my call sent via morse every 10 minutes but as you said, no way to do it on the HTs.

Click to expand...

Here's what I'm talking about......

HT1 Transmit via UHF to RPT
RPT Receives on UHF and Retransmits on VHF
RPT Receives reply on VHF and retransmits back to HT1 on UHF
HT1 Receives Reply on UHF from RPT

Time to ID:

HT1 Identifies on UHF to RPT (ID legally made)
RPT retransmits receives ID on UHF and Retransmits ID on VHF frequency (Legal ID made)

RPT does NOT have capability to transmit its ID on UHF back to HT1

True, the UHF frequency is identified, but the transmitter used by the repeater does not have the capability to ID itself. Legally, all transmitters must ID.

So the ^^^ scenario is not legal.

Now:

HT1 Transmits on UHF to RPT
RPT receives UHF and retransmits on VHF
HT1 receives reply on VHF direct.

ID time:

HT1 Identifies on UHF (ID complete)
RPT receives ID from user on UHF and retransmits said ID on VHF (ID complete)
No further identification required, as the repeater only functions one way.

Hope that made sense

So the problem is giving a voice ID of the control Operator from the x-band to the HT on the UHF side of the link right? And because this is "difficult" most people dont do it and thereby thinks that it makes true x-band operation illegal.

But couldnt you, when it's time to ID, transmit on your dual band HT on whatever VHF frequency the x-band mobile is listening on, thereby sending the operators ID over the UHF link side of things, satisfying the ID requirement?

The ID doesnt have to be automatic. It can be done in voice by the control operator, and needs to be sent over each transmitter. So ID through the x-band repeater out on the 2m side as normal, but then switch your HT to the same 2m freq your x-band is receiving on and transmit your ID, which will carry it over the x-band's UHF side, and voila!

Steven KC9GMX

years ago, West Memphis, Ark fire had a lighting strike and their repeater was out for the count. So their plan B was go to a simplex channel. One of our radio techs took a Icxom W32 (they were cross bandable) and put it in the Mid Continent Building in west Memphis and deliver a uhf radio to the fire station. The setup worked GREAT. Fire thought they had a better system than their regular system. Well it ran for 5 or 6 hours till early morning than quit because the battery crapped out. West Memphis was having storms most of the night and needed something to get them going. Now the4 w32 had been wide banded, was not type certified but under the circumstances, who cared. But a cross band portable can have many uses in an emergency. Height is everything, get the antenna as high as it will go. A colorado group hosted a ballon with a w32 on the cable, for radio comms during a bike race. Well it covered west neb, eastern colorado, and western Kansas. Far outside the bike route. In both the cases, iding was by uses of the system, the system itself could not id.

for iding on the cross band system, I have use a yaesu vx7, running arts mode. id every 10 minutes, th id goes over the link, and uses id on their transmissions. now the taesu vx7 is iding as it sends out my call, which is set to the cross band frequency. all radios id this way.

teufler said:

for iding on the cross band system, I have use a yaesu vx7, running arts mode. id every 10 minutes, th id goes over the link, and uses id on their transmissions. now the taesu vx7 is iding as it sends out my call, which is set to the cross band frequency. all radios id this way.

Click to expand...

I think, I see what you are saying. Kind of like working the crossband repeater in reverse? Now, that vx-7 would have to be received on the 2m input to the repeater, to be retransmitted by the repeater on its uhf side back to the user's ht... (as pictured in my earlier example) As long as each transmitter in the group is physically identified, ie transmitting an ID (one way or another) then all is well.

At least in Canada, ID on cross band repeat is not a biggy. I really don't see the purpose of cross band repeat in an HT. Just another caution, most HT radios when plugged into AC transmitt the 60 hz hum. I use cross band from mobile to HT when I am in a location that the HT cannot even hear the repeater. But with crossbanding, can hear my mobile with the HT and transmit back to the repeater through the mobile. As stated, most amateur radio operators that have worked public service events have used cross band feature or they should know how it works. I have preset memories wilh PL so takes 10 secs. to set up.

robertmac said:

...Just another caution, most HT radios when plugged into AC transmitt the 60 hz hum....

Click to expand...

Only when that supply is unable to supply the full current required by the radio. (Such as using the wall wart that is meant to charge the battery.)

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