I am new to radios and wanted to know if there is such a thing as a bi-directional repeater. Meaning that you may transmit and recieve on a set of frequencies and recieve and transmit back the other way.
Lets say RX 464.xxx DPL 043 and then TX 457.xxx DPL 114 and go back the other way.
RX 457.xxx DPL 114 and TX 464.xxx DPL 043
Thanks for the info
Need Repeater information
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Jonathan KC8RYW
- Posts: 1747
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Sure, you can do this.
Like said above, you will need seperation cans, if they are sharing the same antenna. You don't want 25 watts from the Tx radio going right into the Rx of the other radio. This would just kill the Rx sections.
You could also use two different antennas, at different vertical heights. Not a very popular idea, though. You would still probably need filtering to prevent desense.
7 MHz is a nice seperation figure... the more difference in MHz means the less filtering.
I would call this a "simplex link" not a repeater. When I think of simplex repeater, I think of store-and-forward systems. Sort of like the ones you could buy at Radio Shack, that have a record/playback chip on them.
Make sure that there is NO courtesy tail used in this system, or else the other end will have to wait until the tail is gone before transmitting. This will get very annoying very quickly.
Usually, this sort of setup is used in a cross-band enviroment.
Ex: VHF to UHF. Or, LB to UHF. Etc. So, frequency seperation is far enough apart that only light duplexing is required.
This is usually done with GM300's/Maxtracs or other similar radios, and a RICK. There are a lot of plans at http://www.batlabs.com/ in regards to this sort of setup.
I still have to ask, though, why? Why not just program the mobile/portables for the other frequency? Unless you are working with crystalled radios, and, if that is the case, I feel your pain.
A little disclaimer... if this is for public safety I would recommend contacting a qualified 2-way shop for help.
Like said above, you will need seperation cans, if they are sharing the same antenna. You don't want 25 watts from the Tx radio going right into the Rx of the other radio. This would just kill the Rx sections.
You could also use two different antennas, at different vertical heights. Not a very popular idea, though. You would still probably need filtering to prevent desense.
7 MHz is a nice seperation figure... the more difference in MHz means the less filtering.
I would call this a "simplex link" not a repeater. When I think of simplex repeater, I think of store-and-forward systems. Sort of like the ones you could buy at Radio Shack, that have a record/playback chip on them.
Make sure that there is NO courtesy tail used in this system, or else the other end will have to wait until the tail is gone before transmitting. This will get very annoying very quickly.
Usually, this sort of setup is used in a cross-band enviroment.
Ex: VHF to UHF. Or, LB to UHF. Etc. So, frequency seperation is far enough apart that only light duplexing is required.
This is usually done with GM300's/Maxtracs or other similar radios, and a RICK. There are a lot of plans at http://www.batlabs.com/ in regards to this sort of setup.
I still have to ask, though, why? Why not just program the mobile/portables for the other frequency? Unless you are working with crystalled radios, and, if that is the case, I feel your pain.
A little disclaimer... if this is for public safety I would recommend contacting a qualified 2-way shop for help.
73 DE KC8RYW
Random Motorola Part Number:
SYN1894B - V3m Sprint-branded Battery Cover
Random Motorola Part Number:
SYN1894B - V3m Sprint-branded Battery Cover
looking for a cheap soloution
I have some crystalled expos and the limitation was to spend the least amount as possible. If the link or repeater idea was possible then I would not have to recrystal all of the expos, but it sounds like they will have to be done if we plan to use the expos.
The expo's can only have one DPL for both frequencies and some dummy that has more say has our other radios on two different DPL's on two frequencies...... oh well
It is almost cheaper to just buy some used GP300's or similar it sounds like.
The expo's can only have one DPL for both frequencies and some dummy that has more say has our other radios on two different DPL's on two frequencies...... oh well
It is almost cheaper to just buy some used GP300's or similar it sounds like.
BI-diecrtional Amps and radios YES
Di-Decrtional Yes . Has been
here for 15 years.
All the leaky feeder radio systems use one
normal repeater then are wired up to bi- diectional amps.
Full duplex radios can help out.
Given enough money anything is possible, even replacing the existing radios.
I am not exactly sure that I really understand your question clearly,
but it would seem that you want to extend the range of your radios.
There are two ways that this is done.
Many police cars use a mobile repeater.
This is a small tranciever connected to the police radio, in effect two radios tied together forming a repeater.
The problem with this is that the frequency seperation between one transmitter, and the other receiver require several meg of frequency seperation.
The other approach is a bi-directional amplifier. This works well in buildings, such as shopping centers, or airports, but requires
A rather large seperation between antennas.
The seperation in DB is in the neighborhood of 80-100 db.
These amplifiers do not use decoders, so you can use any number of PL codes.
They have very sharp filters so that only your channel would be amplified.
I think that you could buy very many new radios for the cost of any of these solutions.
Aloha, Bernie
I am not exactly sure that I really understand your question clearly,
but it would seem that you want to extend the range of your radios.
There are two ways that this is done.
Many police cars use a mobile repeater.
This is a small tranciever connected to the police radio, in effect two radios tied together forming a repeater.
The problem with this is that the frequency seperation between one transmitter, and the other receiver require several meg of frequency seperation.
The other approach is a bi-directional amplifier. This works well in buildings, such as shopping centers, or airports, but requires
A rather large seperation between antennas.
The seperation in DB is in the neighborhood of 80-100 db.
These amplifiers do not use decoders, so you can use any number of PL codes.
They have very sharp filters so that only your channel would be amplified.
I think that you could buy very many new radios for the cost of any of these solutions.
Aloha, Bernie
One of the local fire departments in my area has a bidirectional VHF repeater. Their entire area is far enough below a hill that the dispatch center can't hit them at all.
Any traffic on the dispatch frequency is repeated on the second (repeated) frequency, and vice versa. There's probably a priority algorithm (first come, first repeated, or something), but it works. Some of the dispatchers have been known to monitor the output side of it to be able to hear units that couldn't effectively reach dispatch from their areas.
Any traffic on the dispatch frequency is repeated on the second (repeated) frequency, and vice versa. There's probably a priority algorithm (first come, first repeated, or something), but it works. Some of the dispatchers have been known to monitor the output side of it to be able to hear units that couldn't effectively reach dispatch from their areas.