Building FM-Repeaters

When I was going to the HTL I dreamed of building my own FM-Repeater. That time I built a simple squelch controlled circuit that was only used for some testing. Till now I was involved in several real repeater projects. Actually I'm working on a new one.

O E 6 X C D

My last project was OE6XCD which is a 70cm Multimode repeater on a high mountain. Stations 250km from the repeater have been heared so far. Modes APRS, DRM, Fax, Phone, PSK31, SSTV were heared. This list is to be continued. For more informations click on the link besides.

It's a normal suitecase ....
Inside is the hardware of the new 70cm repeater project. Practical to try it with more persons without bringing it on the air. Transmitter is working on Dummyload.

You can see some more with the open case.

Here are the details of the hardware:
2x FK105/460
7Ah 12V Battery

My biggest project so far was the 13cm FM repeater in Vienna. Here are a few technical details:
QTH: Wien Simmering abt. 200m above ground level
Transmitter output power abt. 15 W
Receiver sensitivity abt. 0,15ÁV
Antenna: 19x 1/2 Lambda 11dB gain
Transmit frequency: 2401,900 MHz
Receiver frequency: 2449,900 MHz

This is the final built 13cm repeater. I've integrated all modules into the housing. Most of the modules have been allready made. To some of them I had to do some alignment (Filters etc.) others were constructed by myself. For example the proper connection from the outputs of the controller to the transmitter module. The following matters had to be taken into consideration:
Modulation characteristic as flat as possible in the band af speech to get a naturally transmission.
Filtering of the CW-Station ID because it was a rectangular signal coming out of the controller.
Slight reduction of frequency deviation of the CW ID during open repeater (QSOs).

Because the repeater had to be installed in an open area, the housing must have been water resistant. Here I'm making a rain test. The Repeater housing was tested from all sides except the downside for a few minutes.

I tested the antenna too. I realised a 30m measuring distance for that. The receiving antenna was a 85cm Offset dish with a Coffee can feed. Because the height was 2,75 meters above ground and the beamwidth of the receiving antenna was small there were nearly no reflections from the ground influencing the results.

On May 12th 2001 the repeater was installed successfully. A few days later the 25th OE1WRS was driving with his mobile equipment with transmitter power of 1 Watt and omnidirectional antenna on his car to the radio exhibition in Laa/Thaya. The greatest distance was when he arrived at the exhibition area about 50 km. On the map besides you see the repeater position marked with a red circle and all positions from where OM Werner was readable outside of Vienna marked with a green circle.