The Utah VHF Society

The Hidden Peak Repeater

The Hidden Peak Repeater:
  • Callsign:  K7JL/R
  • Output Frequency:  147.180 MHz
  • Input Frequency:  147.780 MHz
  • Subaudible Tone Frequency:  100 Hz
  • Location:  Hidden Peak (At the top of the Snowbird Tram, in Little Cottonwood Canyon, Utah)
  • Coordinates:  40 Deg. 33" 39' North, 111 Deg. 38 " 39' West (NAD27 Datum)  Grid Square DN40en
  • Elevation:  11,000 Feet (3353 Meters)
  • Coverage:  Northern Utah, extreme Southwestern Wyoming, Southeastern Idaho, spotty coverage into Western Colorado and Eastern Nevada.
  • Link Status:  Full-time linking to the other repeaters served by the Hidden Peak Hub:  147.12 (Salt Lake City, Utah,) 146.86 (Evanston, Wyoming,) and 147.02 (Laketown, Utah.)  The links into points northward (Idaho, Montana, etc.) and the links into points southward (South/Central Utah, Las Vegas, Nevada area) are enabled most of the time.
  • IRLP Status:  This is node 3660 - Not currently operational - See below!

About the Hidden Peak Repeater:

The Hidden Peak (located at the top of the Snowbird tram) is the hub of the Intermountain Intertie.  This system (occasionally referred to as the "Snowbird Link System") is a more-or-less informal collection of repeaters located in northern Utah/Southwestern Wyoming, many of which are supported in part by the VHF Society.  This system is a hub-and-spoke system, with the Hidden Peak site as the hub. For a detailed map of this system, go to  The Intermountain Intertie page.
View of Hidden Peak from the
View of Hidden Peak from the Tram

Note:  Click on any picture on this page to get a larger, more detailed version.

This repeater first went on the air in 1974 and it still operates from the same site and on the same frequency.  During the intervening years, a lot has changed with the repeater:  It is now the Utah hub of the Intermountain Intertie and from this site, it directly connects the 147.12, the 146.86, the 147.02 repeaters together, and it also has links that connect it to the repeaters in the southern part of the state and to the Idaho linked system. You may be interested in visiting the Medicine Butte Repeater page as well.

What originally started out as a fairly simple 2 meter repeater using tube-type equipment has evolved into the linked system that we now use.  It has been been built and maintained, almost single-handedly, by John Lloyd, K7JL with support from the Utah VHF Society.  Owing to this repeater's location, it is able to cover much of the Salt Lake valley (particularly the western part) in addition to the so-called "high valley" communities like Park City, Heber, Duchesne, and Coalville, to name a few.  It is even possible to work this repeater in parts of western Colorado, part of southwestern Wyoming, and even as far south as Price, Utah, if one is in the right location and has a good signal.  Its coverage of the eastern benches of the Salt Lake valley is somewhat limited, owing to the fact that Hidden Peak is several miles in from the front range of the Wasatch and is thus shadowed.

Hidden Peak (or "The Top of the Snowbird Tram")
Closer view of the Snowbird
                    Tram building
The Snowbird Tram building atop Hidden Peak (note the antennas on the roof of the building)

One of the great advantages of mountaintop sites is that, well, they are atop mountains:  They can have excellent coverage, and the view from the site is often spectacular.

One of the great disadvantages of mountaintop sites is that, well, they are atop mountains:  In the Utah winter, most mountaintops are inaccessible except by helicopter, skis/snowshoes, and in some cases via snowmobiles and snowcats.

The Hidden Peak site is rather unique among mountaintop sites in that it is rather easier to access the mountaintop during the winter than it is during the summer.  You see, during the winter, the tram runs very frequently:  Every time there are enough people to fill the gondola, it's on its way.  During the summer, the tram runs far less often and one must often wait quite a while for a ride up or down.  Despite the relative ease of access during the winter, there is no doubt that it is much more comfortable to work on the repeater and/or its antennas during warm weather.  At 11,000 feet, winter winds are always blowing and the wind-chill is, well, chilling!
The rack containing most of
                    the repeater's radio equipment
The rack containing most of the repeater's radio equipment.  Note the UHF repeater's duplexer on top of the rack.

The Repeater
The 2 meter repeater itself isn't really anything too exotic:  It consists of a Motorola Micor repeater connected to a Palomar controller.  What does make it somewhat unusual is the fact that the repeater is really two repeaters:  One is the 147.18(+) repeater that everyone knows about, and the other is a UHF repeater that simply repeats what the Hidden Peak repeater repeats and/or what the other systems repeat.  This forms the basis of the Intermountain Intertie and it works like this:

John Lloyd, K7JL, working on
                  the repeater's power supply
John Lloyd, K7JL, working on the repeater's power supply

In addition to this UHF repeater, there are two additional links on the site:  A point-to-point link goes south to Frisco Peak (north of Cedar City) and another link goes north to provide connectivity to the Idaho system.  Interestingly, there is a mountain directly in the path of the south link (Lone Peak is in the way, and it is over 200 feet higher than Hidden Peak.)  It was discovered that only the 125cm band would work for this link (other bands were tried!) and even though it works, signals are extremely weak.  To get the best possible signals this link uses beams and fairly high transmit power on each end, low-noise GaAsFET preamplifiers and low-loss 1/2 inch semi-rigid coaxial cable.  As a result of all of this effort, the path has proven to be quite reliable.

As with any repeater system, failures do occur occasionally.  Several years ago, a direct lightning strike damaged/destroyed several of the radios in the repeater system.  The entire rack of equipment had to be hauled down to the valley (to John Lloyd's house, actually) and the repeater was, in essence, rebuilt.  More recently, a power supply failed.  This particular Motorola power supply employed a switching regulator as part of its design and it began to buckle under the repeater's normal load.  Finally, a component failed such that the power supply wasn't able to start up properly, so it would shut itself down after such an unsuccessful attempt, only to try to start again.  Each time it went through this cycle, it sent a voltage surge through the system which eventually destroyed some on-board regulation circuitry on several of the repeater controller's boards and the power amplifier for the link transmitter that connects Hidden Peak to the southern part of the state. 

The 2 meter duplexer at the
                    Hidden Peak Repeater
The 2 meter duplexer at the Hidden Peak Repeater


"How much area does the Hidden Peak repeater cover?"

Determining the coverage area of a repeater in mountainous areas (like Utah) isn't a straightforward or accurate process.  The very best way is to simply put a transmitter on the site in question and then see where it covers.  In the case of the Hidden Peak Repeater, there has been 25 years of experience with its coverage abilities, so these parameters are quite well known.  More recently, computer signal strength predictions based on actual terrain modeling have become available.  These take into accout the existance of the mountains and their predicted effects on the signal strength at the frequency of interest.

The image to the right shows the predicted signal strengths based on computer predictions.  The green and brown areas represent good signals while the yellow areas represent weak or nonexistant signals.  There are always some very local exceptions to these predictions, of course:  There are known "hot spots" well into the yellow areas and, conversely, there are some known dead spots in the green and brown areas.  The blue areas are those where coverage is starting to get spotty (but a "hot spot" should be fairly easy to find) and the violet areas are those where a good signal path may be difficult to find.

On the map note that, at first glance, the "yellow" colors around the edges and the brown/orange colors next to the green areas near the middle may look similar.  Keep this in mind to avoid confusion.

For more information about the coverage of the Hidden Peak repeater, go to the UARC Scott's Hill, Predicted Signal Contours page.  This page also predicts signal strengths from Scott's Hill (to the north and east of Hidden Peak) and Farnsworth Peak (southwest of Salt Lake, in the Oquirrhs.)

IRLP connection into the Intermountain Intertie:

The "IRLP" is the Internet Repeater Linking Project - an affiliation of repeater and radio systems that provide connectivity to each other via the internet.  This system allows repeater and amateur radio systems worldwide to interconnect with one another.  For more information, go to the IRLP web page.  For specific node status, go here.

There are several points where it is possible to connect into the Intermountain Intertie via IRLP or even "I-Link" - but most of these are through other systems whereby a radio may be remotely controlled to connect to an Intermountain Intertie repeater.

IRLP Node 3660, however, is intended to provide a direct connection into the Hidden Peak hub repeater.  It should be noted that although the computer hardware is present, it is not on the air!  That is, even if you connect to it, you are talking to nothing - as no radio has been connected... yet.  This continues to be an ongoing project.

If you have any questions about this node, please contact John Lloyd, K7JL.

Predicted signal contours of
Predicted signal strengths of the 147.18 Hidden Peak repeater (Click on image to get a larger version)
WARNING:  The large image is over 200k in size!

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This page was last updated on 20150813

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