This project is considerably further along than the words “future repeater” might suggest.
We already have most of the major radio equipment needed to put a UHF repeater on the air in Perry County.
What’s missing is the easy part.
A tower.
Feed line.
And somebody willing and qualified to climb the tower.
Okay, maybe “easy” isn’t quite the right word.
What We Already Have
The major equipment currently available for the UHF repeater project includes:
- A Motorola MTR2000 repeater
- Telewave 6788 cavity filtering
- An 8-bay 440 MHz folded-dipole antenna
- A coordinated UHF repeater frequency pair
That’s a substantial portion of the radio system already sitting on our side of the project ledger.
The challenge now is getting it properly installed somewhere useful.
The Repeater
The repeater is a Motorola MTR2000.
The MTR2000 was designed as commercial communications equipment rather than specifically as amateur radio equipment, but commercial repeater equipment has a long history of finding a second career in amateur service.
Before deployment, the station will need to be properly configured and tested for its intended amateur-radio use.
We also need to determine whether the final installation needs a separate external repeater controller.
The answer will depend on what capabilities we ultimately want from the system and what the existing station configuration provides.
For now:
External controller: To be determined.
There’s no reason to add another box simply because repeater racks apparently become lonely when there’s unused space.
The Cavity Filters
A repeater normally receives on one frequency while transmitting on another through the same antenna system.
Doing both at the same time without the transmitter overwhelming the receiver requires appropriate RF filtering and isolation.
For this project, we already have Telewave 6788 cavity equipment available.
The cavities will need to be properly configured, tuned, and tested as part of commissioning the repeater system.
This isn’t a place for the traditional troubleshooting technique of turning adjustments until something interesting happens.
The Antenna
We also have an 8-bay folded-dipole antenna system intended for the 440 MHz installation.
A repeater can have excellent equipment in the rack and still perform poorly with an inadequate antenna system.
Height, antenna pattern, feed-line loss, site location, and surrounding terrain can make an enormous difference in useful coverage.
The antenna therefore isn’t simply something that gets attached after the repeater is finished.
It’s part of the system.
What We Still Need
The major pieces still standing between the equipment we have and an operational repeater are:
- A suitable site
- A tower or suitable existing structure
- Appropriate feed line
- Installation hardware
- Professional or otherwise properly qualified tower work
- Final equipment configuration
- Cavity tuning and system testing
- Antenna-system testing
- Grounding and lightning protection
- Final commissioning
There will undoubtedly be smaller pieces discovered along the way.
There always are.
The Site Is the Big One
A repeater is only as useful as the location from which it operates.
Putting good equipment at an inadequate site doesn’t magically create good coverage.
An appropriate site needs to provide useful elevation and coverage while also giving us a practical way to install, power, protect, access, and maintain the equipment.
The ideal site also needs to be sustainable.
Getting permission to install a repeater somewhere is helpful.
Being able to keep it there is considerably better.
Until we have the right site, there’s little value in rushing the rest of the installation.
Feed Line Matters
At UHF frequencies, feed-line loss deserves serious attention.
Power lost between the repeater and antenna isn’t helping anyone.
Neither is a received signal that disappears into feed-line loss before reaching the receiver.
The type of feed line, its length, connector quality, weatherproofing, routing, and installation therefore matter to the performance of the entire system.
This is not where we plan to finish an otherwise good repeater installation with whatever piece of coax happened to be leaning against the garage wall.
Someone Eventually Has to Go Up There
We need a tower.
Then somebody has to put the antenna and feed line on it.
PCARS is not treating tower climbing as an opportunity to discover previously unknown talents while already 100 feet in the air.
Tower work needs to be handled by someone properly equipped and qualified to do it safely.
Gravity has an excellent reliability record.
We see no reason to challenge it.
Power and Protection
The completed repeater installation also needs appropriate electrical power, grounding, bonding, and lightning protection.
If backup power becomes practical at the selected site, that would make the system more useful when commercial power is interrupted.
The final design will depend in part on the site we ultimately use.
This is another reason the project can’t be completely designed around a hypothetical tower at a hypothetical location.
The site influences the system.
What About Linking?
Not every capability needs to be added on day one.
Our first priority is putting a useful, reliable local repeater on the air.
Once the basic system is operating properly, additional capabilities can be evaluated based on what local operators actually want and what makes technical and operational sense.
A repeater doesn’t become better merely because we connect it to more things.
Sometimes reliable local RF is exactly the feature we needed.
Why UHF?
Perry County currently doesn’t have an amateur radio repeater on the air.
A local UHF repeater would give operators another option for everyday communication, experimentation, nets, public-service activity, and emergency communications.
It would also give PCARS something important that can’t be built entirely on a website:
local RF infrastructure.
The Internet is useful.
Hotspots are useful.
Linked systems are useful.
But a local repeater can provide communications between stations in its coverage area without requiring the individual operator’s radio link to travel through the Internet.
That’s a capability worth building.
This Isn’t Operational Yet
We want to be very clear about project status.
The equipment being available does not mean the repeater is operating.
It isn’t.
We still need a suitable site, tower infrastructure, feed line, installation work, final configuration, and testing before this system can responsibly be placed into service.
We’re not going to announce coverage from a repeater that isn’t on the air.
We’re also not publishing an imaginary completion date to make the project look further along than it is.
We’ll update the project as real milestones are reached.
Current Status
Project status: Site Needed
Already available
- Coordinated UHF repeater frequency pair
- Motorola MTR2000 repeater
- Telewave 6788 cavity equipment
- 8-bay 440 MHz folded-dipole antenna
Still needed
- Suitable site
- Tower or suitable antenna structure
- Feed line
- Installation hardware
- Qualified tower installation
- Final system configuration
- Cavity and RF-system tuning
- Grounding and lightning protection
- System testing and commissioning
To be determined
- External repeater controller
- Backup-power configuration
- Any future linking or additional system capabilities
Want to Help?
This is one of those projects where the right person, site, skill, piece of equipment, or connection can make a significant difference.
If you have experience with repeater systems, commercial radio equipment, cavity filters, antenna systems, towers, feed line, communications sites, or related infrastructure, we’d be interested in talking with you.
We’re also interested in hearing from property owners or organizations who may know of an appropriate potential location for amateur-radio infrastructure in Perry County.
And if none of that describes you, but you’d simply like to see the project succeed, you’re welcome too.
PCARS is being built at the same time as the infrastructure around it.
There is plenty of room to help.
Contact us at info@pcars.club.