Here are some photos showing some of the new hardware for the Glen Arbor - Empire Michigan 444.725 and 52.92 repeaters at various stages of the 2004/5 repeater upgrade project.
The project schedule for 2005 includes replacing the repeater antennas and moving them higher on the existing tower. This portion of the project was completed in June of 2005 and has dramatically improved repeater coverage.
Additionally, in the spring of 2004 the control system was updated to include a new Arcom RC210 repeater controller and ancillary devices. The summer of 2004 also saw the addition of satellite voting receivers for both 449.725 and 52.42 MHz co-located with the W8TVC repeater near Traverse City, MI.
It's been a busy two years, but the results were worth the effort and, hopefully, provide excellent service for many years.
|This is the new 440 and 52 MHz
dual-band repeater antenna.
The antenna is a combination of a Decibel Products DB-411 four element exposed dipole UHF antenna mounted aside a Decibel Products DB-212 VHF low band exposed dipole element.
While it would be wonderful to mount these separately, in an effort to make the most efficient use of our available antenna space (hams should be thoughtful and efficient-- and not tower space hogs) by combining them in this manner I expect that the resulting antenna patterns for either band will be more than adequate for our needs (the tower site is near the Lake Michigan shoreline and we don't expect to need much coverage over the lake).
The plan is to mount the antenna with the six meter antenna facing south, which would put the 440 MHz antenna facing the east, and in the direction of downtown Traverse City (25 miles away).
By orienting the antennas in this manner, we can hope to maximize the potential 440 coverage into downtown Traverse City, while also make a (hopefully successful) valiant attempt to provide six meter coverage to a good friend who lives about 70 miles to the south (and who can get into the present 52.92 repeater during 'band enhancements').
|This view shows the Decibel Products
DB-212 element that has been painstakingly cut for use on 52.92/52.42
Thanks to Del, WB8DEL for the gracious donation of this antenna 'to the cause'. The antenna was originally tuned for the 39 MHz range and was chosen to be used for the main repeater antenna due to the fact that it has the additional support braces near the top and bottom that is only found on the larger versions of the DB-212 antennas.
As cut, the antenna itself is 9.5 feet long (+/-) and in testing it loads up quite nicely-- a nice flat 1.3:1 SWR on the frequencies desired (52.92 and 52.42).
As you can see, the antenna is wrapped in a layer of black electrical tape-- much as a cyclist will wrap handlebars (or your favorite stickball bat).
The tape wrapping is per a suggestion on a technical paper published on the Decibel Products website. The wrapping is purported to provide some assistance in the reduction of precipitation noise, which tends to be more problematic on VHF-Low band (which includes the 52.92 repeater). Precipitation noise/static is also more prevalent the higher on the tower the antenna is located. Since this antenna will be quite high on the tower, every effort is being taken to minimize the problems of precipitation noise.
Not shown here is two 'Static Busters' which will also assist in reducing the precipitation noise.
|This view shows the UHF Decibel
Products DB-411 antenna.
This antenna provides an offset gain in this configuration, and this is desirable in our situation, as we are not looking to provide much coverage on the other side of Lake Michigan, or to ships far out on the lake.
The DB-411 is normally mounted on a 10' piece of 1.75" aluminum mast. Because this application has the added 52 MHz antenna, a stronger mast as used than what is normally provided with the DB-411.
As shown, the mast is a 15' piece of triple wall 2" diameter 6061-T6 aluminum. This particular piece was specially treated to a five day journey along the interstate system from Phoenix to Michigan-- an important aspect in assuring its structural integrity.
The DB-411 dipole elements mounted easily to the 2" pipe with only minor 'adjustments' to the clamps, and a few longer stainless steel bolts than what came with it from the factory.
When installed, the overall length of the antenna mast pipe is likely to be less. There is five feet of pipe below the antenna (and 19" above the antennas) which should provide for a wide spacing of the support brackets, and a more structurally strong installation (and provide for more 'options' during mounting). On the day of installation the pipe can be cut to the length that is determined to be best for installation. A sawzall makes fast work of cutting the pipe, but I haven't figured a quick way to add to its length.
|The feedline for both repeaters is to
be replaced also. Shown here is the feedline for the 444.725 repeater, a
nice coil of used Andrew LDF-5-50 7/8" Heliax.
Yea, ideally it would be nice to have a full roll of brand new hardline. At $4.40 - $6.00 PER FOOT, (that's not counting a couple of hundred for truck delivery) it would be irresponsible of me to spend that type of money on this 'hobby project'. As it is, the overall cost of these upgrades is rather high.
The cost of the repeater is borne personally, which leaves valuable government grant money for more important uses (like bulletproof vests for the police or improved medical gear for the EMT's, more hazmat training, etc...).
This is the transmission line for the 52.92 repeater.
I was very lucky to find a nice brand new 500' roll of Andrew LDF-4-50 1/2" Heliax on Ebay this past fall.
Being six meters, the loss in using a long length of the 1/2" Heliax isn't too bad, and it saves not only money, but weight on the tower.
You can see the hoisting sling in the upper right, and the connectors on the left along with the topmost grounding wire.
On both lengths of Heliax I have connectors at the 'free end' that are in place so that I can quickly verify that the antenna ends are fully functional while the tower expert is up the tower-- If there's a problem, it's possible that it could be repaired right then-- instead of having to have another tower climb (they are not free-- it's very hard and very dangerous work that needs to be done by a skilled professional, who rightfully earns his pay).
|Return to the wI0OK/r Glen Arbor repeater page.||Repeater controller upgrade|