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Author Topic: Cross band repeat?  (Read 1023 times)
KK4MSE
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Posts: 7




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« on: December 15, 2012, 03:03:19 PM »

New Ham, first post.
What exactly is cross band repeat? I'm looking at the Yaesu FT-8900 as my next radio
purchase, it has this feature.
Thanks, KK4MSE.
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KB5ZSM
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Posts: 70




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« Reply #1 on: December 15, 2012, 03:29:54 PM »

You can set-up the radio to receive and transmit on two bands at one time. It retransmits what it hears on the other band and visa versa.For an example of use, you can have your 8900 in your car on a hilltop where its antenna has good range for receive and transmit. You could be in a valley below (vary short range do to terrain) with your handietalky and talk to your car on one band (say UHF) while your car repeats what your saying on the other band (say VHF). Now someone on the topside may respond to you on VHF and your 8900 would repeat it on the UHF side where you can hear it. I hope this makes sense as it's not easy to describe.
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AA4HA
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Posts: 1640




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« Reply #2 on: December 15, 2012, 03:46:26 PM »

It is really neat when you can use a single band portable to "talk in" to your mobile unit on something like 70cm and depending on how you have your FT-8900 set-up you can be working in 10m, 6m or 2m at a much higher power level.

If you were were off on some sort of event or in your yard you could extend your portable's battery time by running 1 watt on the portable and a much higher power level on the FT-8900 in a vehicle or as a base station radio.

Here is a good example of crossband repeat in action; http://www.youtube.com/watch?v=T0hP-u4bBRk
« Last Edit: December 15, 2012, 03:48:56 PM by AA4HA » Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
N4NYY
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Posts: 4820




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« Reply #3 on: December 15, 2012, 03:51:13 PM »

Pretty much nailed it. http://www.cvarc.org/tech/crossband.html
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KK4MSE
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Posts: 7




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« Reply #4 on: December 15, 2012, 04:09:22 PM »

So if I use the 8900 as a base, I can use my HT (FT-60R) to opporate remotely at reduced
power. Very cool feature. Thanks, KK4MSE.
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W6EM
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Posts: 900




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« Reply #5 on: December 16, 2012, 06:50:48 PM »

So if I use the 8900 as a base, I can use my HT (FT-60R) to opporate remotely at reduced
power. Very cool feature. Thanks, KK4MSE.


A couple of suggestions.  The 8900 is a very small radio.  And, can get very warm while transmitting all the time in crossband repeat service when you have a contact.  You might want to configure it for UHF low power (5W) transmit power and, 25W or less on whatever the VHF band you use with it when using crossband.

Especially if you separate the head from the radio box and put the box under a seat.
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AA4HA
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Posts: 1640




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« Reply #6 on: December 17, 2012, 08:07:27 AM »

So if I use the 8900 as a base, I can use my HT (FT-60R) to opporate remotely at reduced
power. Very cool feature. Thanks, KK4MSE.


A couple of suggestions.  The 8900 is a very small radio.  And, can get very warm while transmitting all the time in crossband repeat service when you have a contact.  You might want to configure it for UHF low power (5W) transmit power and, 25W or less on whatever the VHF band you use with it when using crossband.

Excellent point! You also have "reciprocity" coming into play. Your portable is only going to be talking in at a certain power level (1-5 watts), you just do not need 50 watts of talkback from your '8900 to your portable. If you cannot be heard by your '8900 it makes no sense that everyone within 30 miles can hear your re-transmission.

Cross band repeaters have been around for a pretty long time. In the language of the Batwing (Motorola) this used to be called "PAC-RT" where a police officer would have a UHF portable that would use a cross-band repeater in the trunk of the car to retransmit through a much higher power radio in the VHF-LOW (30-50 MHz) or VHF-HIGH (150-174 MHz) at power levels of up to 110 watts. http://www.onfreq.com/syntorx/pac.html
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Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
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