Tuolumne County - ? 75 Mhz links ?

zerg901

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ULS License - Public Safety Pool, Conventional License - KZI318 - TUOLUMNE, COUNTY OF - seems that 72.16 and 75.58 are used as high power links for 155.295 - Radio Reference shows 155.295 as "EMS Paging"

72.16 - FXO - 219 watts - on Duckwall Mtn near Sonora

75.58 - FX1 - 193 watts - in Sonora

maybe they use highly directional antennas - so you have to be 'inline' to pick up the links - if they are actively being used
 

es93546

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ULS License - Public Safety Pool, Conventional License - KZI318 - TUOLUMNE, COUNTY OF - seems that 72.16 and 75.58 are used as high power links for 155.295 - Radio Reference shows 155.295 as "EMS Paging"

72.16 - FXO - 219 watts - on Duckwall Mtn near Sonora

75.58 - FX1 - 193 watts - in Sonora

maybe they use highly directional antennas - so you have to be 'inline' to pick up the links - if they are actively being used
The CHP used one of these 72 MHz links to a site that didn't have commercial power. It had beam antennas at both ends and of course, two different frequencies. The state microwave link site was north about 40 miles away from my home and the non-microwave site was also north about 55 miles away, as the crow flies. There are some hills and mountains between me and these two sites. I had no problem picking the furthest north site as the antenna was more or less aimed my way. The closer, state microwave linked, site was aimed away from me, however I was able to pick it up, not quite as clearly, from whatever signal was being radiated from the back of the beam antenna. This allowed me to pick up CHP units using the mobile side of their base/mobile configuration that were 100 highway miles to my north up to the Nevada state line. However, things were changed and the state added microwave linking to this non-commercial power site. There were state agencies on the site that had stand alone repeaters that were then linked directly with the states extensive microwave system. All I can figure is that solar power panels and battery storage systems improved to the point that microwave could be powered reliably. Not long after cell phone towers were added, which normally are not located at non-commercial powered sites.

Tuolumne County has some significant topography as its eastern boundary is the crest of the Sierra Nevada. I think the county has one more 72 MHz link to a site called "Double Dome." It is a very prominent feature in that area of the county. The paths from this site are not entirely line of site down to Duckwall Mtn., which 72 MHz can tolerate, but microwave cannot. Double Dome is remote and I believe is a helicopter accessed site with some scenic limitations on the installation. Obviously there is no commercial power at the site. The Stanislaus National Forest has had a repeater at this site for 20-30 years. I worked on the ranger district that bordered this area to the east, prior to the Stanislaus installing a repeater there. At that time the forest had a huge non-coverage area along our border. Tuolumne County also picked up some coverage they didn't have before after they switched to VHF High from VHF Low. Amador, Calaveras and Tuolumne Counties used VHF low for a long time, due to topography. They had a common low band frequency to facilitate working together. I think their use of low band extended into the 2000's, if my memory is working correctly.
 

mmckenna

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All I can figure is that solar power panels and battery storage systems improved to the point that microwave could be powered reliably. Not long after cell phone towers were added, which normally are not located at non-commercial powered sites.
Last time I was up at the Sweetwater site above Bridgeport, they were set up like that. I'm pretty sure I have a photo of the site somewhere, I'll have to dig around for it.
Extensive solar array and a large LPG tank farm. At the time there was at least one cell carrier up there, as well as a lot of state owned stuff. I was there in the spring, and it wasn't easy to get to. Would require a snowcat in the winter.
Just down the trail a bit, the USMC had some equipment to cover their mountain warfare training center across the valley.
 

es93546

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Last time I was up at the Sweetwater site above Bridgeport, they were set up like that. I'm pretty sure I have a photo of the site somewhere, I'll have to dig around for it.
Extensive solar array and a large LPG tank farm. At the time there was at least one cell carrier up there, as well as a lot of state owned stuff. I was there in the spring, and it wasn't easy to get to. Would require a snowcat in the winter.
Just down the trail a bit, the USMC had some equipment to cover their mountain warfare training center across the valley.
I worked on the Bridgeport Ranger District for 7 years in the 1980's and administered special use permits, which includes electronic sites. Sweetwater was an unknown site, with only the TV district and a data link for snow measuring sites for the Natural Resource Conservation Service. I couple of hams came in my office one day and told me they did a little experimenting and put someone with a 70cm handheld at the site and another in a vehicle that drove from the Nevada state line to Conway Summit and did not find any blind spots, including in the Walker River Canyon. I had already been up there and could tell, just by sight, that this was as good location. I wondered why no one was using the site. A couple of years later CHP and Caltrans came in my office and told me they wanted to apply to establish a new site that would cover blind spots in Walker Canyon. They showed me the location and it was on the east rim of the canyon. I told them they would have to prove that existing sites would not cover the canyon and that Sweetwater was already a designated, surveyed and platted site. They said they knew nothing about it. So they left my office and got busy. They were back that afternoon and said they had no blind spots on 800 MHz and 42 MHz. We went up there and they picked out a lot or two. There are rock outcroppings that divide the site and their lot had no access via the existing route, which was located on the north slope of the knob. I told them a road on the south side had already been approved in the site plan. It was easy enough that I could go out with a clinometer and stake out the road to the right grade and location. They sent up a small dozer while I was there and we built a short road that allowed access to all the lots and eliminated the need for one on the north slope. The rest is history and now there are a lot of users up there. The BLM Bishop Field Office has a repeater up there, the Humboldt-Toiyabe put one up there last year and the Inyo NF put one up several years ago. It is right around 55 miles line of sight from my house in Mammoth and with a rooftop antenna I can pick up Caltrans on 800 MHz. This allows me to hear what the road conditions are from the NV state line to south of Bishop (via their Conway, Crestview and Silver Peak sites).

I was later asked, when I was on the Bridgeport RD, to write the electronic site management direction for the forest plan. No one else knew enough about it, including the radio techs, to write management direction for them. The radio techs knew the sites the USFS were at, but I had driven or hiked to most of them on the forest, including central Nevada. It was fun to do this writing as I had enough knowledge of how these sites work to be able to contribute. It also seemed I was the only employee that had used the Inyo, Stanislaus and Yosemite NP radio systems while traveling our wilderness area, the Hoover, which borders each of those jurisdictions. It is great country with very impressive topography that can't be appreciated from the roads. I covered a lot of it both on foot and by horseback. I flew over most of it in a helo doing winter snow melt recon trips and a couple of SAR missions.
 

mmckenna

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Yeah, it's an impressive site.
I've spent a lot of time out along the 395 corridor. Did a lot of camping along there from Mammoth all the way up to Lobdell lake. Did a lot of exploring out there along the forest service roads in my truck and later a Polaris Ranger. Been to many of the radio sites along there. Conway Summit is always a favorite stop for me when I'm out that way. Great views north and south.
 
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