ABOUT THE STATIONS (Updated 27/04/08)

THE VOICE REPEATER - GB3SD The group has two complete and working 433MHz repeaters so that a spare unit should always be available in case of  a failure of either the RF equipment or the Controller. To find out which unit is in use please check out the Repeater Log. Both use a Philps/Pye F496 PMR Repeater modified for Amateur use but have different specifications. See below for more details. As well as the usual 1750Hz tone burst access the logic includes CTCSS so alternatively a continuous sub audio tone of  71.9Hz can be used. The transmitter is fitted with a modified Amateur Power Amplifier producing approximately 25 Watts ERP and the receiver has a pre-amplifier designed and built by Edward, G3VPF. The power supply is fitted with battery back-up and in the event of a mains interruption the voice repeater continues to function but on reduced power. The transmit frequency is 433.350MHz with a plus 1.6MHz shift to 434.950MHz on receive. Separate aerials are used for transmit and receive.

Repeater 'A', commissioned by Alec, G8GON in the summer of 2000 complies with the 12.5KHz specification now adopted as a standard for all 2m repeaters in the UK and is fitted with the GB3US Mk2 logic. It works well although the logic is not particularly user friendly and the 12.5KHz specification is not fully compatible with most users equipment.

Repeater 'B' commissioned by David, G4RQI in the Autumn of 2001 complies with the 25KHz specification, still the most common standard used by UHF Repeaters in the UK. It is fitted with a more modern Repeater Controller designed by Andy Fisher, G6CUK and built by David, G4RQI. It uses a PIC 16C84 microcontroller and most of the working parameters can be easily adjusted.  It also has the capability of remote command. More information can be found on Andy's web site at http://members.aol.com/andyfi/

GB3SD MORSE CODE A number of people have queried what is sent when GB3SD beacons. The short beacons are simply "GB3SD" and the longer ones "GB3SD Weymouth IO80SQ" To hear the code click here GB3SD Morse Beacon

NB: The above example is for Repeater 'A'. Repeater 'B' has the letter B inserted after the callsign indicating that we are in CTCSS Region B (71.9Hz). It's also a way of telling which repeater is in use.

THE VOICE REPEATER - GB3DR This is a new 2M Repeater located on the same site as GB3SD. It was switched on at 0900 UTC on Saturday the 13th of August 2005. It is on channel RV59 with it's input on 145.1375MHz and output on 145.7375MHz. A CTCSS tone of  71.9 Hz or the normal 1750Hz tone burst can be used for access. The station complies with the 12.5KHz specification now adopted as a standard for all 2m repeaters in the UK. A single aerial is used for transmit and receive and the duplexer and RX band-pass and pager notch filter was built and aligned by Ian, G8PWE. The power output is approximately 16 Watts ERP.

The original repeater was built by David, G4RQI and uses a Kyodo KG110/BSR150 base station. This Repeater beacons every 5 minutes, sending "GB3DR B". As with GB3SD the letter B inserted after the callsign indicating that we are in CTCSS Region B (71.9Hz). The beacon changes to "GB3DR DORSET" once every 25 minutes following closedown. The first of these is always the fifth beacon after the repeater was last used, i.e. the repeater must be idle for at least 25 minutes so don't expect to hear it often if this repeater is in use! The logic was designed by David Osborn GD4HOZ.
For more details see David's web site at http://www.g4rqi.pwp.blueyonder.co.uk/Kyodo.html

In April 2008 a replacement repeater was installed, still using a Kyodo KG110/BSR150 base station but with a new control logic built by Chris, G6WHI. In order to prevent the transmitter being held on for very long periods if QRM or QRN is present a 5 minute transmit time-out is in operation but otherwise the logic is very 'user friendly'. The repeater beacons every 15 minutes by sending GB3DR in morse code.
Full details of the station, including the logic, can be seen on Chris's web site at : www.cstech.co.uk/gb3dr.html

Thanks to Chris, the Group now has two complete and working 144MHz repeaters so that a spare unit will always be available in case of  a failure of either the RF equipment or the Controller.

LOCATION - RIDGEWAY HILL NGR: SY677858 - midway between Weymouth and Dorchester, 3/4 of  a mile east of the A354. The site is at approximately 500ft above sea level and the aerials 40/50 ft above average ground level. You can see the official details including a coverage map of GB3SD here www.coldal.org.uk/reps/gb3sd.htm and GB3DR here www.coldal.org.uk/reps/gb3dr.htm

INTERNET LINKING OF GB3SD Tests were conducted in June 2003 but were discontinued after a few weeks.
At the 2005 AGM, Rob Mott, G0ECX volunteered to provide a link using EchoLink and this was gratefully accepted. On the 25th of November 2005 at 1320 UTC the new facility was switched on and is operational in 'attended mode' most evenings and weekends. GB3SD-R is using EchoLink and the Node Number is 112689.
You can find full details about EchoLink on the web site at www.echolink.org and how to use it on this page www.echolink.org/Help/dtmf_functions.htm Also, by popular request, Rob has produced a brief guide to using the link that you can read here echolink guide Please not that the file is in Adobe Acrobat (PDF) format. 
Please see the NEWS page for the latest update and more details.

PACKET RADIO The two Packet Radio Nodes, WEY2 (GB7SD) and WEY23 (GB7SD-1)  were closed down in April 2005 to make way for GB3DR. WEY2 was subsequently moved to a new QRA at the QTH of John, G0PGT. However the supporting Network collapsed and WEY2 (G0PGT-2) was closed permanently in August 2007.  Full details can be found here WEY2 update

DOCUMENTS Various SDRG documents and relevant information sheets can be found here Documents

THANKS Over the years many individuals have contributed to the success of our group, far to many to name here. The Archive of activities available to read on this site provide some idea of the effort needed to commission and maintain an Amateur Radio Repeater Station. The Group has seen success and occasionally failure in its endeavours but it is important to remember that everyone involved has been a volunteer. The full support of current users is needed to maintain what we have and to continue to provide a facility in the future.

DOCUMENTS In October 2005 a new page was added to the site SDRG Documents

73 de SDRG 27/04/08