View Full Version : cross band repeat
12-11-2002, 10:32 PM
How does "Cross band repeat" work, exactly?
What is meant be V/V V/U U/U?
Is it possible to use a hand held 2 meter only to trasmit to a rig capable of cross band repeat and have that retransmit on 2 meters? Or, will it only transmit on the 2nd band? How about receive, would the cross band repeat rig #retransmit to the hand held or would you have to rely on the hand held only for receive.
I would like to use a 2 meter ht in the yard, garage etc. to talk to a friend on 2 meter simplex.
I know this sounds like a repeater but, thats what I need to know. tnx
12-11-2002, 10:51 PM
That is a repeater, and even with a repeater you cannot receive and transmit on the same frequency at the same time; it requires two frequencies. With a single-band hand-held, you have no V/U, U/V or U/U options. (V/U means VHF/UHF, etc.)
If you set up a "system," including two cross-band duplex radios, you can do this with just the 2m hand-held. But that would take (1) 2m/UHF rig to repeat your signal on UHF in duplex, then (2) UHF/2m rig to receive that transmission and repeat your signal on VHF in duplex, on a different frequency than originally used by your hand-held.
With proper identification and using otherwise unoccupied frequencies, this is perfectly legal.
However, it would be cheaper, and simpler to buy a dual-band hand-held and a single V/U radio.
If you want an inexpensive way to greatly extend the range of your 2m hand-held when you're in the yard or garage, etc., install a well-elevated 2m omnidirectional "base station" antenna with a length of flexible coaxial cable that reaches those places. Plug the HT into that cable and walk around, using the "big" antenna.
This isn't far-fetched at all. I do it, myself. I have a 2m "base station" antenna on the roof with a length of hard line going down into the ham shack. From there, I can switch (using a standard coaxial switch) the feedline to my "main station" 2m FM rig, or to either of two flexible coaxial feedlines, one of which goes into the garage, and the other which goes to the backyard patio with about 40' of surplus cable and a connector. This allows me to "plug in" and walk out to the pool, or the spa, or the garden, while maintaining 2m contact with someone just as though I was on the "base" unit.
Total cost of doing so is the cost of a coax switch and some extra cable.
12-11-2002, 11:48 PM
You might try what is called a passive repeater. This involves two antennas connected to each other. If your friend is always going to be in a particular location (i.e. home QTH), you could put a vertically polarized beam up in the air (on top of your house, a tower, etc.) and then connect it to a small ground plane type of antenna located about 6 feet off of the ground in your back yard. Use at least RG8/U (or the more modern designated RG213/U) coax to connect these two antennas together. Of course, both antennas have to be for the band in use, in this case, 2 meters.
If your friend is going to be mobile, then you might be able to use a second ground plane or other omni directional antenna on top of the house. However, this may not prove as productive as using a beam.
What happens is that as you transmit, the signal is received by the ground plane and is reradiated by the beam up in the air. As your friend transmits, the beam receives the signal and it is retransmitted by the ground plane. This type of arrangement has been used to get signals into areas that are shielded by terrain, into tunnels, etc. I have used them on 900 MHz spread spectrum systems that normally have about a 1/4 mile maximum radius to be able to use hand-held digital readers up to as much as 3/4 mile away.
You can build both antennas for very little cost and the feedline cost shouldn't be that much. Of course, your friend may be too far away for this to work. But, it is definitely something that you can try. The nice thing about a passive repeater is that it doesn't require any power, is perfectly legal, and can be built for a minimum cost.
we have a gang that hangs out on 146.580 simplex and many of us use (or can use) cross band repeat....many of the newer, and older, dual band radios will do it ...i use an icom ic 2800 ...pick a 440 freq,(445-447 is listed as "shared by auxiliary and control links, repeaters and simplex") #listen to it for a couple weeks to be sure there is no activity, and a alinco dj s41 ht on 440....when the sig is received on .58 it is repeated by the 2800 on the 440 freq and the reverse takes place when i transmit on the 440 ht the 2800 transmits a signal on .58. #i set the power to the lowest setting on 440 and a low power setting on the 2800. #keep in mind that the transceiver is 'key down' for long peroids of time. ..from the legal end...you are in control,do not leave this set up on if you are not able to control it, and when you id, you id on both bands......also, many of the dual band radios will allow the tt pad on your ht to bring this function on/off remotely...... if cross band repeat is not clear, in the manual, for your radio, do a google search for the mods ...many are capable but they don't go into it in the manual.
hit the wrong button before i finished...this set up not only works around the property, but i also use it to go out on the hiking trails about 5 miles from the house, down to the store etc.
12-12-2002, 07:35 AM
"Cross-Band" repeat means exactly that.
Repeating from one band to another.
"In band repeating" Gets complicated and
expensive in a hurry. (Duplexers, High
quality receivers, etc)
To "cross band" repeat with an output on
two meters would normally mean you would need
a UHF H.T., and a Mobil or base station "dual band"
radio. In actual practice, It is best to also have
a dual band H.T. so you can properly monitor
and ID on your "Link" frequency, and output frequency, #if needed.
Most any decent two meter base station or mobil
antenna usually works out OK, UHF VSWR is normally
low enough to operate, Although the antenna pattern
on UHF is mostly high angle of radiation, It makes
no difference, As "cross band" operation is usually
just in your neighborhood anyhow. The wireless
use of a shirt pocket 100mw HT that can talk long
distances will sell you on how neat "cross band"
repeat really is! #NO wires attached! Output from
your base or mobil station at full power! #
Have fun! # #http://www.qrz.com/iB_html/non-cgi/emoticons/smile.gif