see SQ
contact us
Comag Porty

GB3SQ REPEATER NEWS updated 22 April 2017


The receive problem on the 70cm input has been resolved but there is still what appears to be considerable QRM at most times. Extra filtering wll be included to reduce the problem. ------

A new version repeater is currently being assembled at G8AJN and will incorporate many improvements that were added on to the existing repeater. It is hoped that it will be ready by Summer 2017











Jan 2016:
The latest version of the repeater is now installed at SQ site. It is radically different and much more power-efficient than the existing one. The GB3SQ repeater was off-air whilst this major swap-out work was being undertaken with the old repeater being completely removed to G8AJN to allow the new repeater to be fitted to the existing 19" cabinet. A major factor in the running costs of the repeater is electricity. After 2 years of operation it was found that there were no occasions where the repeater was in use between the hours of 12am and 12pm. Based on this it was decided that the repeater will shut down completely between midnight and 10AM each day. This includes the receivers and control circuits. An over-ride option by SMS has been added to enable immediate shutdown if requested by UK authorities, but also gives an option to bring the repeater back to standby overnight by the designated keeper if special circumstances require it do so.
At 10AM it will be on in standby awaiting an input signal and will show a carousel of test slides and testcards from 7pm to 8pm each evening.


 CHANGES 2016:

The  PanSat 23cm receiver has had difficulties with intermittent signals and often locked up on the sound channel. Since we no longer use the 23cm audio for the DTMF input we returned to using the BigSat with audio channels strapped to mono ( to overcome the left/right swapping firmware problem). The PanSat has been moved to replace the streaming receiver (Porty) at G8AJN which is currently used for BATC streaming. A problem arose when different signals were used into the repeater and caused to the sound to distort until the carrier was dropped for a few seconds and given time to reset. Two receivers are currently on trial at the repeater site, they are both STARSAT SR-S10. They appear not to suffer from the sound troubles.

There was recently poor reception on 70cm and the preamp, filter, SUP up-converter and down-cable have been replaced and tests have shown it is now back to nominal performance.



NoV Received 13 Sept 2013
Finally the green light for the repeater was given. The repeater was switched on officially on 20th October. Some tweaking of video and audio levels is still required but it is now ON-AIR..

The Repeater has been running consistently since switch-on Autumn 2013.
The main problem we have is with the nearby trees when windy or waterlogged, causing intermittent reception to distant members QTHs. An improved slot aerial has been fitted with some more height to try to get over the tops of the trees. Another option would be to trim the offending trees a little, but they are not on our property so it will take some negotiation. A final, more dramatic option is to find a different site!

We are fully digital !
With the success of the DigiLite project all the GB3SQ locals are now sending digital transmissions, many operators have already got digital gear running and the remainder will be converting during the coming months. We have dropped the 13cm option that we were looking at as an alternative input channel. By using digital signals we can squeeze into a 5MHz bandwidth so we will drop back to 1249 region for our input to enable the various filters and receivers to be re-aligned. From July we are using input 1249MHz input.

Currently there are 6 stations sending digital signals in the Bournemouth area . There are several others preparing to join them.


Original (current) GB3SQ Main Unit
(excludes receivers,PA and PSUs)

The new version

The original application was submitted to the RSGB for vetting in February 2009. Due to the planned changes to the UK 23cm Amateur Bandplan and other factors, the space for sufficient analog inputs is severely limited. To enable several tv inputs to share a part of the 23cm band it will be necessary to use a digital-only input. A revised application was submitted in February 2010. The repeater build is now finished and a updated repeater with a commercially manufactured single pcb is being assembled now.

  • The Alford slots being installed in June 2013

    The rear of the house seen here faces north-west.
    Electricity is routed from the upstairs flat to the consumer fuse box and meter in the shed.

    The single Alford slot, pole and 2mtr talkback aerial fitted in May 2014.

  • ------------------------------------
  • A single Alford slot aerial has been made. It is mounted onto a aluminium scaffold pole and double clamped to the chimney breast.
  • By using a duplexer we can share the slot between transmit and receive.
  • Coverage to the east is better than to the west due to a line of trees to the west of the repeater site.

    The current transmissions are :
    DIGITAL: 1304 MHz. Symbol rate: 4000.  FEC: 1/2 
    VPID:256(=hex 0100) APID:257(=hex 0101) PMTPID:4095(=hex 0FFF)

    Input is on 1249MHz Symbol rate: 4000.  FEC: 1/2 
    VPID:256(=hex 0100) APID:257(=hex 0101) PMTPID:4095(=hex 0FFF)

    and 436MHz Symbol rate: 2000.  FEC: 1/2 
    VPID:256(=hex 0100) APID:257(=hex 0101) PMTPID:4095(=hex 0FFF)

    DTMF control is on the 2mtr talkback channel of 144.525MHz vertical..
    Talkback on 144.525MHz is re-broadcast on the right audio channel and also on the BATC stream.

    INPUTS are on 1249 MHz digital 4Ms/s or 437MHz digital 2Ms/s. PIDs are standard ATV UK settings. See for details.


    A capture from the BATC stream on Good Friday 2012 of successful first transmission to GB3SQ using the DigiLite encoding system. 1280Mhz running 4Ms/s. Sound and vision were good received on a Porty/SL55 on a distance of approx 3 miles.

    A number of different 23cms receivers have been tried and they all have a drawback of one sort or another. The Manhattan Plaza is currently being used at 'SQ. Because of the audio channel problems that develop when a weak signal is coming and going we have moved the DTMF to the 2mtr talkback channel instead. We have not yet found a receiver capable of coping with all the different encoder parameters and with a locklight option either included or adaptable.

    To TopPrevious pageBack to MENU