Operational Parameters for GB3WS
GB3WS is the two meter repeater that serves an area targeted at the northern part of West Sussex and the South-West parts of Surrey. Because of its geographical location it is very difficult to tailor the aerial pattern, and signals are received across a great deal of northern East Sussex as well as south London.
The repeater uses two ICOM IC F110 transceivers fed to a 50 watt PA. The PA is running at 25 watts. The repeater is fed via the duplexer to a single dipole antenna approximately 68' above ground. The coaxial feed is Andrews LDF4-50.
Single antenna working is achieved by four Sinclair cavities and a phasing arrangement based on a hybrid ring but modified by G4EFO. Each cavity produces a notch of around 55dB at the unwanted frequency, with an insertion loss at the wanted frequency of about 0.5dB
The repeater logic is derived from a CAT300 DX series controller purchased at the Dayton Amateur rally U.S.A. from CAT Technology.
Repeater time out is set at three minutes ( Aug 07 ). Every 15 minutes the repeater will send a voice ID. On the hour it announces GB3WS and then the time. At 15 minutes past and 15 mins to it gives voice ID GB3WS. On the half hour the repeater gives a voice ID followed by the CTCSS sub tone frequency. Through audio is permitted and a user can continue to use the repeater during and I.D. period. If talk-through is in operation the voice ID is replaced at a convenient break by mcw ID, de GB3WS E. ( E being the 88.5hz sub tone.) The young lady that gives the occasional "good morning" or "good evening" announcement is a bonus, and I guess she sneaked in as an illegal immigrant. I've taken all the covers off the repeater, but alas, I am unable to find her anywhere.
By keying up and sending 555 in DTMF tones the repeater will reply with the time. If this system is abused it will be switched off.
Access to achieve talk-through requires a carrier plus an 88.5 hz sub audible tone. The repeater also transmits an 88.5hz tone.
The logic has many functions, some of which users will have heard demonstrated, but I have tried to keep the operation parameters very basic. The logic parameters are easily changeable via the software on the laptop computer and can be loaded onto the repeater in a couple of minutes.
Mike G4EFO April 2008