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eHam Forums => Mobile Ham => Topic started by: KC0WDZ on January 19, 2008, 06:38:36 AM



Title: Cross Band Repeat Confusion
Post by: KC0WDZ on January 19, 2008, 06:38:36 AM
I am new to the concept of cross band repeating. I have to ask, can you use the function to repeat on the same band? (VHF/VHF) Or can you only repeat VHF/UHF?


Title: Cross Band Repeat Confusion
Post by: W3LK on January 19, 2008, 06:47:39 AM
Cross band is just what it says - transmitting on one band and receiving on another, VHF to UHF or UHF to VHF.

73,

Lon - W3LK
Naugatuck, Connecticut


Title: Cross Band Repeat Confusion
Post by: K0BG on January 19, 2008, 08:02:07 AM
Before you decide you're going to do this, make sure you know what the FCC rules and regs are regarding cross band repeat. Done incorrectly, and you jeopardize you license.

Alan, KØBG
www.k0bg.com


Title: Cross Band Repeat Confusion
Post by: KA1OS on January 19, 2008, 08:19:24 AM
If you are talking about using a mobile rig or HT with cross-band capabilities then no, you can't repeat within bands (As Lon notes: It wouldn't be called 'cross-banding' in that case).

The main reason why your mobile or HT can't act like a same-band repeater is filtering. For in-band operation with most rigs, the filters are insufficient to keep the transmit signal out of the receiver and either deafening or damaging the circuit. You'll also observe the same sort of desensing if someone close to you transmits on a frequency near to which you are trying to receive (This is pretty common at hamfests). Repeaters get around this problem by running the signals through sharp, tightly tuned filters and sometimes, by using separate transmit/receive antennas. These filters are neither compact (VHF filters can be several feet tall) nor rapidly retuned without good test equipment.

Separating signals is much easier when the transmit and receive frequencies are far apart (e.g. 145MHz vs. 440 MHz). That is why mobiles and HTs can operate as cross-band repeaters with their smaller filters.


Title: Cross Band Repeat Confusion
Post by: KB1LKR on January 19, 2008, 10:07:34 AM
To K0BG's point: beware of ID and control requirements not only for the transmitter w/ you (often a 70cm HT) at the end of the RF chain, but (the trickier part...)also for the cross-band transmitter (often a 2m/70cm cross-band capable mobile) in the middle of the RF chain, (assuming you, not someone else, is its control operator).


Title: Cross Band Repeat Confusion
Post by: N2IK on January 22, 2008, 06:29:16 PM
You can avoid the id issues by one-way repeating. That is if you have dual receive HT and can hear the repeater from your location while sending on 440 simplex. If so, Kenwood and some other radios can be set to receive on 440 simplex and transmit on selected 144 frequency simplex( the repeater's input).  Nothing happens  on 440 when the repeater is keyed by the other side of the conversation. Kenwood calls this locked band repeating, I think.

When you id on the 440 side from your HT you are also IDing on the 144 side.

Does Yaesu do this also?

73 de Walt N2IK