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Home Jan 6, 2024 Trip to the K9KAO Repeater Photoblog


Ham Radio Nerd
Apr 14, 2002
The K9KAO 440 Mhz repeater sits atop Sunset Peak in Southern California at 5200 feet, providing terrific coverage to the greater Los Angeles area. This last weekend, three of us took the trip up the mountain to do some much needed maintenance, including replacing the Motorola Quantar power amplifier and installing a new Wifi downlink dish. I decided to make a photoblog of the most interesting parts of the trip as well as the repeater site itself.

The first leg of the trip is a drive up to Mt. Baldy Village, which is at the base of the the Mt. Baldy Ski Resort. As you reach the village, you head west for a few miles before arriving at the dirt road that heads up to the repeater site. After a couple of years of heavy rainfall in SoCal, the road is in serious need of maintenance and it's basically now a Jeep trail. Much of of the trail is on the north side of the mountain which offers nice scenery and views of the taller mountain range to the north.


Here's a shot looking to the north with a portion of Mt. Baldy at 10,000 feet visible to the right.


The view up this trail is breathtaking and pictures just don't do it justice. Here's another image looking to the north showing much of the San Gabriel Mountain range.


The last few weeks had a few days of light rain in the city and the temperatures in the mountain are low enough to bring a bit of light snow. I was still a little surprised to see snow on parts of this trail, though. The snow wasn't deep, but it was frozen and slick so being a bit cautious was certainly warranted.


Eventually the trail winds around to the south side of the mountain as you start to get closer to the radio site. This is where the road starts to get a bit "fun". There are a bunch of spots like this:


As we go up, the road gets narrower and we start to see the radio towers.


A little farther and more towers appear.


Now a few pictures off the good stuff. This is the vault and tower where our repeater is located.


And here's a couple of shots of the tower itself.


The receive antennas is shared by a couple of different repeaters housed at the same location and is at the very top of the tower, visible here.


Coming around from a different angle, the transmit antenna is about half-way up the tower. In this shot, it's the massive antenna second from the left which extends through the pic.


The first task was to replace the failed power amplifier. This repeater is one of the busiest in SoCal and it's not uncommon for it to be busy most hours of the day, every day. This type of duty cycle certainly puts a strain on the PA. Fortunately the effort to do this is just a simple module swap on the bottom left of the Quantar. In this shot, you can also see that we use an Arcom RC210 controller.


Once that was done, it was time to replace the WiFi dish to reestablish internet service to the repeater. Here's Henry, K9KAO mounting the dish from the roof.


We made bearing and azimuth calculations to the uplink site, so aligning the dishes only took about 15 minutes. All of the existing ethernet and wifi inside the vault was still working, so as soon as the dish work was done, internet was back online. Initially, this just allows us to control the repeater remotely, but we will soon be hooking it up to other services such as Allstar. Before we got off the roof, I took a 180 degree panoramic shot from the site to help provide an idea of the coverage. The Pacific Ocean is on the horizon.


After lunch and a couple of cold beers, it was time to head back. Here's one more shot of the repeater coverage view from the road with the building to the left.


The ride home was uneventful, but since it was now late afternoon, the new sun angle provided for additional opportunities for pictures of the scenery.


One last pic, half way back down the trail.


It's an 82 mile round trip drive which takes a while due to the trail time. On a clear day like this, the views are stunning, making the time fly. Now that winter is here, we'll have to be a little judicious about when we travel to the site, but that won't hold us back from adding new capabilities to the system in 2024. Hope you enjoyed the ride along!

Help Users
  • No one is chatting at the moment.
  • @ wavrider:
    sea que sea que,
  • @ ButtFuzz:
    C'mon let me take you on a Sea Cruise! (Maybe there is someone to talk to out there?)
  • @ ButtFuzz:
    Just for the Halibut.
  • @ ButtFuzz:
    Seems to be dead on the radio lately. I don't know if the conditions are horrible, or more likely my weak antennas. I may head up in the mountains on Wednesday and see if reception / transmission is improved.