GB7JB 70cm

The principle system for GB7JB is of course the repeater itself.  This is a Motorola DR3000, the specification for which is shown below.

The TX and RX sockets are connected to a normal wide bandwidth duplexer, which is all that is necessary to allow successful operation, at the 9 Mhz split, between the input and output frequencies.

In the image above, you will see a typical duplexer lying on top of the repeater unit.

The output of the duplexer is then connected to the antenna, via a lightning arrestor and 50 feet of LRM400 coax.

The system is single antenna working, with a 4 stacked dipole array, similar to the image shown below.

You will also note that, in the bottom left had corner of the Repeater unit, there is a mains power supply, this of course is redundant at the "JB" site, but it does enable safe connection to the high current and fully regulated 13.8 volt dc feed, since the entire site is run from a nominal 24 volt battery system, which is float charged by a Solar Power system.

The system schematic is shown below.

Just a quick comment about the Solar Panels.

Each panel is comprised of 72 cells, in a 6 x 12 array, measuring 1.6m x 0.9m.

Two panels are rated at 250 watts peak and two at 190 watts peak.

The nominal full load output voltage is 35 volts dc.

As will hopefully be appreciated, 880 watts worth of power at 35 volts D.C., can give you quite a shock.

These types of panel are not to be played with.  Hence they are mounted high up on the tower, well above the anti-climbing panels, the anti-climbing paint, and the barb wire.

The following, shows the predicted coverage for the local channel / slot.

The predicted coverage is of course identical for both channels / slots.

Please note, that at the time of writing, 28th March 2015, the above coverage is limited by the fact that the antenna has not yet been installed on the top of the tower.  It is currently only 13 feet agl.

This page last updated: 29th March 2015 @ 1700 UTC.