[Repeater-Builder] Re: Adding Remote Base to a Repeater
Dwayne, Gary is correct. To really comment with good solutions one needs to know: Repeater frequencies (as you've given) Remote base frequencies (suspect linking will be upside down from a repeater pair so will be txing near repeater input). What antenna seperation can you work with. Seems you need height to make the remote base work so does this mean the repeater and remote base antennas have to be close together??? One problem with cavities and notch filters are the seperation of frequencies for with a notch there also has to be a pass. Cavities are used a lot and do work if the frequencies allow it. 73, ron, n9ee/r --- In Repeater-Builder@yahoogroups.com, k4fmx [EMAIL PROTECTED] wrote: --- In Repeater-Builder@yahoogroups.com, skipp025 skipp025@ wrote: ldgelectronics ldgyahoo@ wrote: Yes, the tower spacing is vertical (not horizontal), yes the tx/rx on the repeater is 443.3 and 448.3 (5 MHz split) Don't get sideways over the vert/horz terms. We would be concerned with both the vertical and horizontal locations. Vertical distance is an easy best bang for the buck option. But horizontal distance and location per side of a tower is also quite handy. Ok, now to fill in some of the blanks I left out. This is why the group is so cool things I thought were meaningless turned out to be important. The repeater power is 20 watts, the remote base is 10 watts. Relative to the grand scheme of things... your power output is not that big of a problem to work with. The repeater is an Exec II. The remote base is a Kenwood TK-805 (just because I have a stack of them). The broadness of the TK-805 is part of the problem and this could all go away by switching to another Exec II for the remote base. I've seen a lot of tk-805d radios used as links... and they are very popular animals. It would be worth your while to include some band pass selection (cavities typical) in series with the radio. For the splits, we have both (high TX and low TX) here in Maryland. The overall plan is to connect the new repeater with the remote base to an existing hub repeater on 449.225 TX and 444.225 RX. Clint Eastwood called it a cluster $%^ in one of his movies. Keep in mind the closest frequency spacing from any transmitter to any receiver is your largest gorilla in the room. Skipp, I like the additional notch in the repeater duplexer trick. That alone may do it. I do a lot of close spaced in-band commercial radio repeating and the notch in the reciver antenna path is da dope to take out the unwanted visitor. If this is a fixed frequency remote used only for repeater linking... then you should also include a notch or suck out cavity on the remote radio, tuned to the repeater transmitter frequency. We would assume the remote radio to be operated half duplex? I did the T-to-T thing with 2 and 4 band pass cans. The loss was in the 5-6 db range with 2 cans on each side. Not really worth it. If it were 2db per side, I would live with it. Something is wrong with your setup... you should be able to do better than the 5-6 dB loss value. Since your power levels are relatively modest (vs what they could be) you could actually replace the band-pass cavities dual port-hole with simple suck out notch cavities on the unwanted frequencies as long as things don't get too crazy with choices of frequencies, power level and a few other considerations. Thanks again for all of the input. Sometimes just talking it through helps a bunch. Dwayne Kincaid WD8OYG Just think of the gas money you'll save by not having to drive to the repeater site to disable a locked up link/remote base system. cheers, skipp Dwayne, I am not sure what the actual setup is that you are trying to co- locate on the same tower. Maybe you could re list the frequencies? Here are a few facts about isolation that may help: Vertical separation of antennas on 450 Mhz of 10 feet gives almost 50 db of isolation. 20 feet vertical separation gives around 60 db of isolation. The spacing is figured from center to center of each antenna. Horizontal separation of 10 feet on 450 Mhz gives about 30 db of isolation. Horizontal separation of 100 feet on 450 Mhz gives about 50 db of isolation. It is much easier to get more isolation with a notch cavity than it is with a pass cavity. Combining with cavities will usually require an isolator on each transmitter in addition to the cavities. A pass cavity or a low pass filter is always required after an isolator to reduce 2nd harmonics generated by the isolator. When adding a second station on a tower you need to figure the isolation between each stations tx and rx the same as if you were building a repeater. With separate antennas the antenna
[Repeater-Builder] Re: Adding Remote Base to a Repeater
--- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: ldgelectronics ldgyahoo@ wrote: Yes, the tower spacing is vertical (not horizontal), yes the tx/rx on the repeater is 443.3 and 448.3 (5 MHz split) Don't get sideways over the vert/horz terms. We would be concerned with both the vertical and horizontal locations. Vertical distance is an easy best bang for the buck option. But horizontal distance and location per side of a tower is also quite handy. Ok, now to fill in some of the blanks I left out. This is why the group is so cool things I thought were meaningless turned out to be important. The repeater power is 20 watts, the remote base is 10 watts. Relative to the grand scheme of things... your power output is not that big of a problem to work with. The repeater is an Exec II. The remote base is a Kenwood TK-805 (just because I have a stack of them). The broadness of the TK-805 is part of the problem and this could all go away by switching to another Exec II for the remote base. I've seen a lot of tk-805d radios used as links... and they are very popular animals. It would be worth your while to include some band pass selection (cavities typical) in series with the radio. For the splits, we have both (high TX and low TX) here in Maryland. The overall plan is to connect the new repeater with the remote base to an existing hub repeater on 449.225 TX and 444.225 RX. Clint Eastwood called it a cluster $%^ in one of his movies. Keep in mind the closest frequency spacing from any transmitter to any receiver is your largest gorilla in the room. Skipp, I like the additional notch in the repeater duplexer trick. That alone may do it. I do a lot of close spaced in-band commercial radio repeating and the notch in the reciver antenna path is da dope to take out the unwanted visitor. If this is a fixed frequency remote used only for repeater linking... then you should also include a notch or suck out cavity on the remote radio, tuned to the repeater transmitter frequency. We would assume the remote radio to be operated half duplex? I did the T-to-T thing with 2 and 4 band pass cans. The loss was in the 5-6 db range with 2 cans on each side. Not really worth it. If it were 2db per side, I would live with it. Something is wrong with your setup... you should be able to do better than the 5-6 dB loss value. Since your power levels are relatively modest (vs what they could be) you could actually replace the band-pass cavities dual port-hole with simple suck out notch cavities on the unwanted frequencies as long as things don't get too crazy with choices of frequencies, power level and a few other considerations. Thanks again for all of the input. Sometimes just talking it through helps a bunch. Dwayne Kincaid WD8OYG Just think of the gas money you'll save by not having to drive to the repeater site to disable a locked up link/remote base system. cheers, skipp Dwayne, I am not sure what the actual setup is that you are trying to co- locate on the same tower. Maybe you could re list the frequencies? Here are a few facts about isolation that may help: Vertical separation of antennas on 450 Mhz of 10 feet gives almost 50 db of isolation. 20 feet vertical separation gives around 60 db of isolation. The spacing is figured from center to center of each antenna. Horizontal separation of 10 feet on 450 Mhz gives about 30 db of isolation. Horizontal separation of 100 feet on 450 Mhz gives about 50 db of isolation. It is much easier to get more isolation with a notch cavity than it is with a pass cavity. Combining with cavities will usually require an isolator on each transmitter in addition to the cavities. A pass cavity or a low pass filter is always required after an isolator to reduce 2nd harmonics generated by the isolator. When adding a second station on a tower you need to figure the isolation between each stations tx and rx the same as if you were building a repeater. With separate antennas the antenna isolation gets you the biggest part of that isolation. On a multiple stations tower also don't ignore tx to tx isolation as you can have intermod problems if proper isolation is not provided. Keep in mind just because a transmitter is low power that most of the same problems still exist as with high power. A 10 watt transmitter is only 10 db difference from a 100 watt transmitter when figuring isolation required. 73 Gary K4FMX
[Repeater-Builder] Re: Adding Remote Base to a Repeater
ldgelectronics [EMAIL PROTECTED] wrote: Yes, the tower spacing is vertical (not horizontal), yes the tx/rx on the repeater is 443.3 and 448.3 (5 MHz split) Don't get sideways over the vert/horz terms. We would be concerned with both the vertical and horizontal locations. Vertical distance is an easy best bang for the buck option. But horizontal distance and location per side of a tower is also quite handy. Ok, now to fill in some of the blanks I left out. This is why the group is so cool things I thought were meaningless turned out to be important. The repeater power is 20 watts, the remote base is 10 watts. Relative to the grand scheme of things... your power output is not that big of a problem to work with. The repeater is an Exec II. The remote base is a Kenwood TK-805 (just because I have a stack of them). The broadness of the TK-805 is part of the problem and this could all go away by switching to another Exec II for the remote base. I've seen a lot of tk-805d radios used as links... and they are very popular animals. It would be worth your while to include some band pass selection (cavities typical) in series with the radio. For the splits, we have both (high TX and low TX) here in Maryland. The overall plan is to connect the new repeater with the remote base to an existing hub repeater on 449.225 TX and 444.225 RX. Clint Eastwood called it a cluster $%^ in one of his movies. Keep in mind the closest frequency spacing from any transmitter to any receiver is your largest gorilla in the room. Skipp, I like the additional notch in the repeater duplexer trick. That alone may do it. I do a lot of close spaced in-band commercial radio repeating and the notch in the reciver antenna path is da dope to take out the unwanted visitor. If this is a fixed frequency remote used only for repeater linking... then you should also include a notch or suck out cavity on the remote radio, tuned to the repeater transmitter frequency. We would assume the remote radio to be operated half duplex? I did the T-to-T thing with 2 and 4 band pass cans. The loss was in the 5-6 db range with 2 cans on each side. Not really worth it. If it were 2db per side, I would live with it. Something is wrong with your setup... you should be able to do better than the 5-6 dB loss value. Since your power levels are relatively modest (vs what they could be) you could actually replace the band-pass cavities dual port-hole with simple suck out notch cavities on the unwanted frequencies as long as things don't get too crazy with choices of frequencies, power level and a few other considerations. Thanks again for all of the input. Sometimes just talking it through helps a bunch. Dwayne Kincaid WD8OYG Just think of the gas money you'll save by not having to drive to the repeater site to disable a locked up link/remote base system. cheers, skipp
[Repeater-Builder] Re: Adding Remote Base to a Repeater
The issue is that I want to add a same-band remote base to an existing repeater. The main problem is that the remote base is a transceiver and I can't find a way to provide proper isolation to/from the repeater. It's not a problem if the hardware is done smart and right. Even fairly close spaced remotes can and do work. Here are the frequencies, but it looks like it really doesn't matter all that much. The repeater transmits on 443.300, receives on 443.800. We're using a typical UHF pass-reject duplexer with about 70 db of isolation between those two freqs. The remote base will transmit on 444.225 and receive on 449.225. Aside from what we see as a possible typo, you'd be running the remote base radio almost 1 MHz away from the repeater. Are you sure the remote base frequencies are indicated right? Don't you want to tx high and rx low... but I know different areas of the country flip the UHF Band back and forth... I can put two antennas on the tower, but my horizontal space will be less than 20 feet. Vertical spacing is butta' (better) but horizontal spacing is also usefull. The only practical free lunch you get when trying this type of setup is the isolation provided by the vertical distance between antennas. From the pile of spare parts, I have a multitude of UHF band pass and notch filters. I would also not be opposed to adding something like a pass-notch duplexer if there is a way to configure it to work. First: Put an at least one additional notch in the repeater receiver path set up to reduce (notch) the remote base radio tx frequency. From my testing, it seems that the real issue is that the remote base is a transceiver and there is pretty much no way to add anything except notch filtering. Adding band pass cans will filter either the tx or the rx, but not in any combination (that I can find) to do both. Yes you can... let me throw this out just so everyone can toss it around in their noodle. Why can't you set up 2 or 4 band-pass bottles as a basic duplexer on the remote base frequencies. Then instead of using each side of the duplexer as the normal or expected duplexer tx or rx port... make up another coax T just like the antenna T side of the duplexer and tie the two duplexer ports back into one path on the other side of the bottles.Wheels turning yet..? If the remote base had a separate tx and rx, then a band pass can with a notch can (on the repeater freqs) on each side would probably work fine. Anyone have a good solution? Yeah, but the California Lotto hasn't found me yet... Dwayne Kincaid WD8OYG Other things are possible... but you should also consider using as low as possible power on the remote base radio and depending on the various receiver(s) quality... you might need some additional filtering. cheers, skipp
[Repeater-Builder] Re: Adding Remote Base to a Repeater
Thanks guy for all of the answers. This has really given me something to think about. Let me start by acknowledging all the obvious typos that have already been fixed (darn and I proofed that twice). Yes, the tower spacing is vertical (not horizontal), yes the tx/rx on the repeater is 443.3 and 448.3 (5 MHz split) Ok, now to fill in some of the blanks I left out. This is why the group is so cool things I thought were meaningless turned out to be important. The repeater power is 20 watts, the remote base is 10 watts. I can't really get much more vertical separation as the tower is only about 150 feet. Any lower for the remote base antenna and I can't make my link. The repeater is an Exec II. The remote base is a Kenwood TK-805 (just because I have a stack of them). The broadness of the TK-805 is part of the problem and this could all go away by switching to another Exec II for the remote base. For the splits, we have both (high TX and low TX) here in Maryland. The overall plan is to connect the new repeater with the remote base to an existing hub repeater on 449.225 TX and 444.225 RX. Skipp, I like the additional notch in the repeater duplexer trick. That alone may do it. I did the T-to-T thing with 2 and 4 band pass cans. The loss was in the 5-6 db range with 2 cans on each side. Not really worth it. If it were 2db per side, I would live with it. Milt, excellent info. I didn't want to dig into the radio to get to the T/R switch. If I have to do that much work, I'll just mod up another Exec II. The ascii drawings were cool. It looks like swapping in an Exec II for the remote base is making the best sense. That way, I can just put a separate band pass can on the TX and RX sides. If I need more, then notches tuned for the remote base and placed on the repeater's duplexer will take care of it. Thanks again for all of the input. Sometimes just talking it through helps a bunch. Dwayne Kincaid WD8OYG
