DERBY AMATEUR TELEVISION

GROUP

GB3DH

The audio in is fed to a 6mhz oscillator which is mixed with the video giving standard intercarrier sound. The other board supplies an audio test tone and vertical black and white bars which make the unit a useful signal source. There is also a small circuit which monitors the 12v rail because if batteries are being used and they run down the Gunn diode will be destroyed if its volts drop below 5v so the monitor removes the Gunn supply if the main supply drops to 10v. A video only TX . The power regulator transistor can be seen bolted to the aluminium casting using the ground terminal screw hole.

A problem has been discovered that has resulted in the beacon slide show freezing on one testcard. Also the pc which runs this slide show, has been found that when rebooting remotely does not give a video output to the TX. As a result to reset the pc to run the testcard slide show, a physical visit is necessary to manually restart the output to the TX. In order to resolve this problem the repeater has been temporarily turned off until Monday to allow the fault to be resolved.

The test transmissions from GB3DH continue while work is being carried out on the completion and testing of the logic boards. Other necessary work up at the site has had to be completed as a priority which has taken longer than anticipated due to poor weather conditions. When there is a reasonable break in the weather work is planned to raise the antennas from their test position up to the full height allowed on the NOV. This should greatly improve the coverage to the predicted area from the limited area covered at present. Unfortunately the group has reduced in numbers recently, but the work still continues with this long term project and will continue until completion of the project. It is anticipated if all things continue to go to plan that full operation will commence this summer.