Agreed about the separate TX and RX antennas.? However I do this for two sets of repeaters at one of my sites.? 1 antenna two transmitters, two receivers 3 db of loss in each branch work well.,? on the RX side I added a 6 or 9 db preamp this works very well? both TX to both RX isolation is >110db.? I also do this for a pair of UHF links? the splits aren’t anywhere near as good as the first system 420/423?? And 422/425??? Only 2 watts from each transmitter? again 3 db loss per branch UHF LOG pointed tot eh other site 30 miles away -70db signal level no receiver issues.

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This can be done it takes a lot of time, patience and the right equipment, it requires looking at all four parameters while making adjustments then looking at all the other ports. RX BP windows can be a pain getting all the cables right.? 200 khz at UHF is as close as I will try for TX-TX spacing.

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However what wasn’t mentioned is what TX power levels the OP is using.

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Each or the repeaters TX output is 25watts for the filters I built

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Jim

AJ,

As far as ISP provider goes you are at the mercy of what you can afford.? Some sites I have stuff in has a real cool ISP that knows hams don’t use much bandwidth he gives them a free connection just asks that they don’t go gobbling up tons of mbps.? He might rate limit IDK but never had an issues with his connection.? At two of my other sites my friend transport and ISP connection to a rural community I get a few MBPS for using my buildings.?

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Cradlepoint is pretty good stuff even the older 4G LTE still does the job.? I just don’t like relying of cellular companies.? Stay away from the RPi LTE modems we tried those out they kind of worked but after the second or third one my network guy gave up on them.? We tried starlink as a backup, trouble there is the latency? 400ms!!? Bandwidth was up and down but hey it is better than nothing.

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Google SIMS are probably the cheapest option I forget how the account has to be set up but I did play with it awhile back?? look into that.

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As far as site to site connectivity I do a couple things.? Two of my sites have licensed MW with a unlicensed 2.4GHz backup other places just have internet.? If you can I would suggest doing PTP IP networking.? Depending on how far apart your sites are and if they are LOS you could transport your own network.?

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Next I would look at some sort of routed network.? I deploy a DMVPN IPSEC Tunnel network using Cisco ISR routers.? This is highly scalable and very adaptable to ROIP.? It does require a static public IP somewhere.? AT&T charges me $15/mo for 5 static IP’s.? I have redundant hubs.? It is a pretty steep learning curve but has worked very well for me for the last couple years.? I have a friend back in FL that has one of my spoke routers.? I shipped him back a preconfigured router and ROIP hardware all he had to do was plug it in to his ISP router and talk.?

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The advantage of a routed network is you can segment things.? Part of my network requires multicast, for that I can specify what LAN the multicast is transported on so it doesn’t flood the entire network with traffic.? I use a separate LAN at each site for site control, cameras, virtual com ports, raspberry pi’s, charge controllers, Monitoring is UPS devices etc.? I haven’t got as far yet as adding IP phones but that is coming.? I can also specify what LAN or IP address has access to the internet and which don’t.? this also leads it self to SNMP monitoring of network devices.

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Once you have the basic configuration down it is pretty easy to copy.? The static routing tables are all handled in the hub routers, the spoke routers don’t require as much configuration.? Running NHRP allows spoke to spoke sessions.?

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The cisco ISRs I use are all pretty cheap.? I like the Cisco 2800, 2900 ISRs, as well as the 880, 881, 890, 891 and 892 routers.? I even have an 819 which has an LTE modem embedded that travels with me.? I can turn it on and use either a cellular connection or plug into the WAN port of the router from whatever ISP I get a connection from.

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Other application you might look into are tailscale (a virtual VPN) very useful can be deployed on routers, installed on you phone, computer, I use this in conjunction with my routed network s a backup back door in.

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Anyway there are my thoughts.

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TNX Jim

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Dan I have to disagree with you!? I have done combining for both UHF and VHF.? Is there loss? Yes, is there loss in any duplexer filter system? Yes!? If done correctly, do they preform well yes!!? It can actually can be beneficial because all frequencies are being taken into consideration.? Not some ham hanging his BPBR duplexer up and hook it to his repeater and his antenna and not paying attention to everything else on the site!?

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I have done this where there was less than 1 meg between one groups UHF receiver and anther transmitter!? Neither saw degradation, why because it was thought out!? Separate master RX antennas and speperate TX antenna, and filtering to accommodate everyone.

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One of my sites has 4 ham repeaters and 2 commercial repeaters on two antennas, no issues. repeater operate everywhere between 420-461 MHz.? same goes for VHF. Losses range from 1.5db to 3.5 db. but better than not having them at all!

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In some places this is only practical, no more space on the tower, cost of another feedline run, antenna or even time might not be possible.? GMRS repeater combining with ham repeaters are a perfect example, one might exist but both could if the correct filtering is done.? Not only that but by virtue of how combiners are build it necessitates ?the use of isolators and bandpass filters which are good practice at any location!

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Does it mean you have to have the right tools sure it does, hammers don’t fix everything.

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As for the damaged feedline, replace or pull it leaving something like that on the tower is just asking for problems PIM etc.

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Jim

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