EAST DEVON REPEATER GROUP

GB3EX

WE URGENTLY NEED DONATIONS

TO PAY THE SITE RENTAL OF £350 PA

CAN DONATE NOW WITH A CREDIT CARD USING PAYPAL

click on the paypal link at the bottom of this page and you will be taken to a secure site .

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GB3EX

Location:

Exeter Racecourse Haldon Hill

5 miles S/W of the City of Exeter, Devon England

NGR: SX 898,834
Site Elevation: 231 METRES (758 feet.)

RX Antenna Height: 60 feet.

For a Detailed location Map click HERE

Welcome to the EXETER 70cms Repeater page. The repeater GB3EX, has been operational since 1972.

The considerable coverage of the repeater extends over most of east and south Devon,

North along the M5 motorway to the Devon/Somerset border,

East along the coast to Weymouth and Portland.

Technical Overview

Channel: RB-0 (RU-240) Tx. 433.0 MHz, Rx. 434.60 MHz.

TRANSMITTER

Modified Pye T471,+ MRF646 PA producing an Output Power of 40 Watts MAX. Effective Radiated Power set at 25 Watts. Frequency Reference, Standard High Stability Crystal. 5 KHz peak deviation.

RECEIVER

Modified Pye R460. Upgraded front-end, with a mutek lna preamp giving a 12db SINAD reading at approximately 0.2uV/-121dbm. Squelch hysteresis 3db. IF's 1st 10.7MHz, 2nd 455KHz. Frequency reference, Standard High Stability Crystal. .

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THE ANTENNA SYSTEM

The RX antenna consists of a phased array of 4 half-wave dipoles which are mounted at 90° to each other along a 2.5 metre pole. mounted at the top of the mast

The TX aerial system consists of commercial grade folded dipole antenna, mounted about half way up the mast on the north side.

Also shown on the picture are the GB7EX Packet node aerials and the GB7EX-1 23Cms aerial position

CAVITY FILTERS

Both the TX and the RX are fitted with tuneable cavity filters. The receiver cavity is tuned to reject at the TX frequency (433.0MHz), likewise the transmitter cavity is tuned to reject at the RX frequency (434.60MHz). Each cavity provides a notch of around 20db, thus between TX and RX ports there exists a rejection of some 40db. When added to the antennas 45db of isolation this provides a total TX port to RX port isolation figure of some 85db thus making receiver de-sense non-existent.

CONTROL LOGIC

The Control Logic was designed by the University of Sheffield (GB3US) MK1 version,

OPERATING CHARACTERISTICS

Beacon callsign every 10min ,

1750Hz tone burst access,

Two high-level 1750Hz pips spaced 5sec apart. (to allow others to call in,... no logic implications)

No timeout

No aggro

No grief

you are all welcome on our box..!!

CTCSS FACILITY............

Not active on gb3ex ..............to be added later

Operating Through GB3EX

ACCESSING

Accessing GB3EX achieved by the normal 1750Hz Tone-Burst

Accessing using 1750Hz.

To Access GB3BS the 1750Hz (± 25Hz) tone should be at half system-deviation (2.5KHz) and have a duration of between 200mS and 400mS.

PIPS AND TIMERS

Once the repeater has been correctly accessed normal conversations or overs can take place. When the squelch on the repeater closes (after an over) will send a "PIP".

This first pip indicates to the users that the input is clear

The forbidden gap is there so that other stations have an opportunity to break in on a QSO etc.

If the repeaters input remains clear for a further five seconds beyond the first pip being sent the second pip will follow. The second pip does not reset any timers it just indicates that the repeater is about to close down. If the input still remains clear for another five seconds after the second pip the repeater will close down.

TALKTHROUGH TIMER............NONE

TIME-OUT..........NONE

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THE EAST DEVON REPEATER GROUP

PACKET RADIO NODES AT EXETER

NOTE THAT THESE WILL BE CLOSED DUE TO LACK OF USE BUT WILL REMAIN ON AIR UNTIL A FAULT DEVELOPS

ALSO AT THE HALDON SITE ARE THE PACKET NODES

GB3EX (EXE2) ON 144.9375Mhz

this comprises of a PYE M294 Radio and a Tiny 2 TNC running THE NET X1J software (tpcpip active)

(this node provides deviation and signal strength indication useful for setting up your deviation.. type mh!! note this is a 12.5khz radio..use low deviation..)

CROSSLINKED TO

GB3EX-1 (EXE23) ON 1299.425Mhz

this comprises of a yaesu tranciever and another Tiny 2 TNC running THE NET X1J software (tpcpip active)

the 23cms node provides access to the ipplepen bbs at south devon and access out of the s/w via 23cms pathe to wey23 at weymouth

CROSSLINKED TO

GB3EX-7 (EXE70) ON 439.975Mhz

this comprises of a pye m296 and a paccomm 9600 baud TNC running THE NET X1J software (tpcpip active)

FAULTS & QUERIES

If you suspect a problem or possible fault with the operation of GB3EX its associated packet nodes or would like to comment on it's service Please contact the repeater keeper G8UWE qthr 01395 264872 or at gb3ex@g8gon.com

WE NEED YOUR SUPPORT

When using GB3EX, or any of the packet nodes at the site, please remember that Local Amateurs have given their time and cash to providing the service. Repeaters don't just come out of thin air, they require dedication and support. If a Repeater is not given that support it will die.

PLEASE REMEMBER - Repeaters cost money to run & maintain. There is usually Site rent, Electricity, & Insurance bills to be paid. Some work like aerial maintenance & rigging must be done by professionals, their fees do not come cheap. So your support by being a member of the Repeater Group is essential in the day to day running & up-keep of GB3EX.

Without your support the repeater would cease to exist. we do not set an annual subscription we only ask for money when we need it ...we do not ask for any specific amount for the repeater from our supporters

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TREASURERS ADDRESS...

MRS M JEFFORD

37 MARIONS WAY.

EXMOUTH. DEVON EX8 4LF

01395 264872

CHEQUES MADE PAYABLE TO ..

EAST DEVON REPEATER GROUP

YOU CAN PAY NOW WITH A CREDIT CARD USING PAYPAL

click on the paypal link below and you will be taken to a secure site ...