The KF7LDG Repeater Project

This January I purchased an Icom ID-880H from Ham Radio Outlet in New Hampshire because there was a good penetration of D-STAR users in the Connecticut and Western Massachusetts areas.  I ended up having a lot of fun with the mode, and worked it a lot in the car, and even chatted with D-STAR folks in Dayton.  Unfortunately, upon moving back to Corvallis I found out that the nearest D-STAR repeater was up on Mt. Hebo (W7GC operated by the Oregon Coast Repeater Group) and wasn't able to be accessed from a mobile in Corvallis.

This caused me thinking about how to solve this problem.  After considering a few different options, including setting up a DVAR Hotspot, I decided to set up a full blown D-STAR repeater at my employer's datacenter in Corvallis.  I didn't want to purchase the Icom stack because of the expense and the lack of experimentation potential.  I talked to David Lake a bit while I was in Dayton about his D-STAR repeater software.  This led me to the conclusion that I should wait for his software, and build the repeater based on a standard PC.

Even though a standard PC has some flexibility, there are some downsides as compared to a dedicated controller, and I decided that I should try to make a low power consumption PC that could run on 12VDC. I also wanted to get rid of as many rotating parts as possible, mainly the disk drive.

After that, my repeater experience is really limited, so I embarked on a process to learn as much as I could about repeater design and implementation.  I think the main thing that I learned is that repeater components are expensive, and it's the parts you least expect (like the duplexer and feedline) that can be the significant drivers of cost.

I made the decision to use the Tait T800 series 1 repeater for the RF gear because David was using it, it was nicely 19" rack mountable, and seemed to be cheaply available on the used market.  I met a guy from Idaho at the SeaPac convention in Seaside, OR that had a stack of them for sale, and I made arrangements to purchase a rack of equipment that had both 440 MHz and 2m repeaters in them.  I'm still waiting for him to complete the cleanup and refurbishing on the unit, and I'll go to Boise and pick it up.

After repeatedly seeing their ads in QST and researching them on their web site, I chose Telewave to provide the antennas and duplexer for the project.  I'm going to be using a 2-bay folded dipole at the top of the tower for receive, and a 4-bay folded dipole 10 ft. below the receive antenna for transmit.

The antennas will be on a Rohn 25G tower in a self supporting configuration at 40' tall.  Because of our proximity to the Corvallis Airport, 45' is around the maximum height we can support without notifying the FAA and FCC and going through that process.  If things work, and it seems necessary to increase coverage, we'll look at maybe adding some more sections to the tower.

I formed a club with a few friends of mine that are interested in Ham radio and digital communications.  We obtained the callsign KF7LDG for the Willamette Valley Digital Radio Association to support the repeater project.  I've applied for coordination from the Oregon Regional Relay Council, and we'll see what frequency we get.  That's the primary thing that's holding up the duplexer order.

Throughout the project, I'll be posting pictures and updates so that people can see what's going on, and hopefully the information can help out others trying to complete similar projects.