GB3NO

Location Norwich
gb3no

 

 

This repeater is co sited with GB3NR.
Frequencies, RM0, 1297.000/1291.000 MHz
GB3NO, has been active since 14/02/1987, it was primarily built as a beacon for us locals, the nearest beacon to Norwich being GB3MHL (ex BPO) which is not audible without a reasonable


Technical Information

Antennae
Jaybeam/Homemade experimental or  Home-made dual Alford slots.
Transmitter
G4DDK design with FSK/AFSK inputs, fitted with crystal heater, this unit o/ps about 10 mW at final frequency, this is amplified in two stages, the first being a YU3UMV design ,the second is a 57762 slab power o/p is about 8W. CTCSS active during talk through, 94.8Hz.
Receiver
7 pole inter digital convertor (modification of design in ARRL handbook), G4DDK LO  and crystal heater ensures stability, three stages of amplification precede the convertor, two modamps  and a  gasfet  (G3WDG design). and a 7 pole inter digital filter. Rx sensitivity is better than -120dBm.
The IF unit is a Philips T4002. CTCSS decode,  94.8 Hz, only used for access in parallel with 1750 Hz. The filtering in this receiver is for 25 kHz Channel Spacing.
Duplexer
No single aerial operation here, just two Philips AE450F
cavities used in 3/4 wave mode with modified coupling loops, providing -25 dB
notches and less than .5 dB insertion loss. Antennae feeder ………….They are only 21 ft long, so Westflex 103 is used.
This equipment is operated by the Norwich Repeater Group
Donations to G4LUA (QTHR)
The Group wish to thank all those who contributed designs components, materials and time,
The Repeater Management Committee, The Microwave beacon co-ordinator, And Norwich City Council.

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