I have been dealing with close coverage issues and weighed a number of options. I have decided to replace a higher gain antenna with a lower gain Telewave dipole which has a downward tilt option.
In order to achieve my needed ERP I will need to replace the current repeater or add an amplifier and new duplexer.
Before proceeding with this project has anyone had luck using an amplifer with the UHF gr1225. I have been told because the repeater is basically a mobile radio I may end up with a reception issue.
The long term plan is to replace the repeaters with units that are voter friendly and the duplexer/amplifer would be used with the new repeater.
Thanks Mark
gr1225 UHF amplifier
Moderator: Queue Moderator
Re: gr1225 UHF amplifier
I've never considered the GR1225/RKR1225 series repeaters to be "high performance". In my opinion, they were designed to be an "in house" type solution for applications such as school campuses, shopping centers, construction sites, etc. And that's where I usually find them when I'm called out to fix them.
I'd suggest you consider upgrading your equipment to something a bit newer. Perhaps an MTR 2000 or Quantar station if it's within your budget. Even the MotoTRBO XPR 8300 series repeaters are a bit higher performance than a GR1225 and they function fine in analog mode.
When we have a customer who is looking for a solution for an in-house/campus type operation, we usually specify the XPR series repeaters and just run them in analog mode.
They can support voting operation with an external status tone generator such as the Raytheon/JPS unit. So can the GR1225 for that matter.
Anyway, my rant on the GR1225 is over.
It sounds like you are on the right track with a lower gain antenna and some electrical downtilt. So many people forget that higher gain does not necessarily equal higher performance, and this is most definitely the case with close-in situations. You might just try a unity gain antenna, you'd be surprised how well they work without any electrical downtilt. If it's a severe case of close-in issues, you are right with the electrical downtilt.
You might also look into a null fill antenna system if you're still having issues.
I'd suggest you consider upgrading your equipment to something a bit newer. Perhaps an MTR 2000 or Quantar station if it's within your budget. Even the MotoTRBO XPR 8300 series repeaters are a bit higher performance than a GR1225 and they function fine in analog mode.
When we have a customer who is looking for a solution for an in-house/campus type operation, we usually specify the XPR series repeaters and just run them in analog mode.
They can support voting operation with an external status tone generator such as the Raytheon/JPS unit. So can the GR1225 for that matter.
Anyway, my rant on the GR1225 is over.
It sounds like you are on the right track with a lower gain antenna and some electrical downtilt. So many people forget that higher gain does not necessarily equal higher performance, and this is most definitely the case with close-in situations. You might just try a unity gain antenna, you'd be surprised how well they work without any electrical downtilt. If it's a severe case of close-in issues, you are right with the electrical downtilt.
You might also look into a null fill antenna system if you're still having issues.
Re: gr1225 UHF amplifier
I have successfully added TPL 100watt amps to 2 GR1225s. They work fine and provide the in-building coverage I need now....heavy in-building coverage. The key is a really good set of filters/duplexers and quality jumpers. If you are using mobile (reject/reject) duplexers, you can hang it up.
I agree with d119 in that a better quality repeater would be better, but budget required me to do it a different way.
I agree with d119 in that a better quality repeater would be better, but budget required me to do it a different way.
Qball