Latest Status

[G8GKQ]

GB3NV is located on Winchester Tower in Norwich city - JO02PP

Technical Information

TX

3406 MHz, consists of an Antennair dual channel DTX1 running at 830 Mhz, up-converted by an Airspan board to 3406Mhz. PA unit is a 20w Ex Ionica (Nortel) linear unit backed off to 5 w Average ouput.

TX antenna is a vertical Andrews 10dB Colinear (approx. 2 degrees down-tilt), fed with 11m of LDF-450A.
TX DVB parameters:

SR2000KS/s, CH1 (main) Video PID 100, Audio PID 101 & CH2 Video PID 200, Audio PID 201 (HEX), FEC 5/6. Net DVB data rates are approx :CH1 2.3Mb/s & CH 2 1Mb/s.(MPEG2)

RX

437Mhz, consists of a 7 pole ID filter & 433 cavity notch, PGA103 pre-amp, SUP2400 up-converter & a Converted DVB-S Sat Rx.

RX antenna is a “Big Wheel” fed down 15m of LDF450A.

RX DVB parameters: SR 2000KS/s , Video PID : 100 ,Audio PID 101 (HEX),FEC all DVB-S.

The analogue FM inputs on GB3NV were installed on 16-10-2016.

The equipment consists of Comtech modules and custom made baseband strips to correct the poor response of the on board circuits.

The Radio frequency inputs are filtered with inter-digital filters.

At 1248MHZ a custom made 7 pole filer is used, coupled to a Alford slot antenna which has a reflector fitted to reduce the radar interference this seems to be working well but note this attenuates all signals to the NNE of Norwich by 20dB. Sound sub-carrier at 6.0MHz

At 1316 MHz another receiver of the same type is used with a commercial filter, this will link TN to NV when complete. The linking is automatic, if TN is not in use with a local input NV will be relayed via TN.

At 2340MHz another Comtech receiver is used and 2 x 5 pole commercial inter-digital filters in series to reject the strong on site signal from the beacon GB3ANT on 2320.890 MHz. The antenna is an Alford slot and is omnidirectional. Sound sub-carrier is 6.0 MHz.

Video and audio switching is done with a commercial switcher from Kramer Model No VS601. This is controlled by custom logic using 4000 series CMOS and NE567 sync detectors. The linking control is done using CTCSS modules that are fitted in the control rack.

Thanks to G4WVU, G8VLL, G0FVG, G0TZZ and G0LGJ for getting it to air.

It is currently in Beacon mode.

Thanks to G7KZZ for initial Stream and Tony 2E0TCZ for current stream http://www.batc.tv/streams/gb3nv

More information at http://www.gb3nb.org.uk 73 de Norfolk Repeater Group.

Information provided by Mark G0LGJ