KF4PXZ/R Technical Information

Here is a brief overview of how the system is set up.

This is a multi-receiver linked repeater system. All of the receivers are toned, so a Channel Guard (CTCSS) tone of 123.0 Hz is required to access the repeater. Contact me for more information.

Two Meter System

The two meter repeater system is a full duplex repeater with six receivers. The system utilizes a voter/comparator and is interconnected with UHF links. Click here for the approximate locations of the receiver sites. These are all linked back to the control station in Bardin and then on to the transmitter using UHF as described below. The six link receivers & the VHF receiver in Bardin are connected to a LDH Electronics RVS-8 voter. Multiple receivers provide adequate coverage without the expense of leasing an elevated site, and can help reduce co-channel interference. Would you like to know how a voter works ?

The receiver radios are General Electric Mastr II type VHF receivers - GE MVPs (Mastr Value & Performance). I can provide exact details of the equipment if you are interested. This equipment provides a receiver with a solid front end & link transmitter with an adequate heat sink. The GE radios are crystal controlled and feature a tuned 5 helical coil front end that virtually eliminates intermod. Back at my house I am using GE Mastr Pro UHF receivers as the link receivers. These receivers are connected to the voter which is interfaced with the controller, a CAT 1000, by Computer Automation Technologies. The signal is then linked back to the repeater transmitter located in Hollister. The transmitter is a General Electric Mastr Executive II base station driving a GE Mastr II continuous duty base station amp @ 100 watts. I am getting about 70 watts out of the duplexer. The way this thing is set up is probably much more complicated than it needs to be, but ...

All receivers except for the one in Bardin are linked back to Bardin on UHF - even the one in Hollister where the transmitter is. The signals are voted, then sent to the controller. The controller output is connected to another UHF link back to Hollister for the transmitter. Even if your signal is only received by the receiver in Hollister, it's going to come back to Bardin before being retransmitted. I know it makes for an extra link, but there are many reasons why it's done this way.

First of all, Bardin was the original location of the transmitter. All of the linking antennas & feedline are here on this tower with all the remote sites aimed this way. Moving that would be a very time consuming and costly proposal. Not only would all these antennas & feedline need to be moved to Hollister, all the remote sites would have to be re-aimed. Finding places to safely mount that many antennas on the tower would be a problem. Obtaining permission to put that much equipment on the tower could be a problem.

Secondly it's a matter of room. When it is in one location the repeater takes up two large radio cabinets. I am a guest in Hollister & there is only enough room in the small building for one cabinet and the DOF radio equipment. I am not being charged to site there, so I have to take what space they will allow.

Thirdly the autopatch. I can easily justify a residential rate for the phone line because it is to my residence. Once I move that phone line to a place of business, it becomes a commercial phone line with higher rates and is subject to a different tax structure.

Lastly is maintenance. Most maintenance issues involve something with the voter & the controller. They are the most complicated components of the system. The site is 15+ highway miles from my house. It would not be pleasant to have to drive that far each time I had to check on something.

The "Palatka Project", now known as The Florida Crown Repeater Network.

Early in 2001, during an unusual band opening, one of my remote receiver link transmitters interfered with the W4IZ 146.700/444.400 repeater in Jacksonville. We have a common remote receiver link frequency, and that signal was reaching from here all they way up there. Thus the idea was born to connect the two repeaters. NOFARS owns the W4IZ repeater and is the ARES group for the Fla. Crown, consisting of Duval, Clay, Bradford, Nassau, Baker, Putnam, and St. Johns Counties. The W4IZ repeater has adequate coverage to all these counties except Putnam. This was very evident in "Fire Storm '98". We agreed to link the two repeaters together. On June 15, 2001, the repeaters were linked on 70 cm side of the W4IZ repeater using a GE Mastr Exec. II on this end connected to the remote base port of the controller. The link is nearly DFQ, which is quite an accomplishment considering that there is about 45 miles between locations. The link is normally available for anyone to use. If you find it off line and need it, simply ask for assistance. Call on the radio or autopatch me @ 601. This system is now called the Florida Crown Repeater Network .

The Six Meter Repeater

The six meter repeater is a split site repeater with about 1 mile of separation. The transmitter is a General Electric Mastr II VHF Low band mobile and the receiver is a General Electric Mastr Executive II base station that has a VHF Low band receiver and a UHF transmitter for the linkback. I have a MVP monitor/receiver for the linkback receiver and this is fed into the voter in the number 8 position. The receive antenna is a homebrewed six meter dipole antenna. For transmit I am using a Decibel Products DB-212-2. I realize that I should have it the other way around, with the receiver connected to the DB antenna, but there is a strong signal here on 52.010 and it just won’t work out. The main six meter receiver requires a 123.0 Hz tone. There is a second six meter receiver located in Hollister, and it is carrier squelch.

What was that noise ??????

As I am sure you all are aware, Amateur Radio uses UHF on a shared basis with the military and other services. On occasion, you will hear a whining, grinding noise mixed in with the repeater signal. This is ground radar - could be from a military source, an airplane flying by, or a tug boat pushing a barge out on the river. There is nothing I can do about it short of not using UHF for interlinks, and it only happens every now and then. Fortunately it has never been strong enough to key the repeater by itself, but it sure can be annoying when it's mixed in.

Any questions? E-mail me.

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