Input 51.250 output 50.750 Access CTCSS 77.0 Hrz encode / Decode
We are at the present running tests on the repeater and any reports from around the bay, and further afield are welcome. This will be very useful as maybe the next step will be to fit a RX pre amp to the reciever (Kindly donated by Peter of Garex in Exeter) , which may help to the small amount of insertion loss that we have on the Duplexer.The loss is really not that bad, the RX port has 1.5 db and the TX port has 2.0 db, so if anything the TX side is a little higher. So maybe an RF amp on that side would help things out.
If you've not got 6 meters FM and are looking for a reasonable priced transciever Peter G3ZVI
of Garex Electronics in Exeter can supply the AKD 6001 www.garex.co.uk
We still need help with the repeater both now and ongoing. As this is a private repeater and has no association with the local Radio Club. Please do not be put off by this as anyone wishing to join in with the project, or just use the repeater, are more than welcome.We have decided that this repeater will not be commitee run in any form so should we call this the "Peoples Repeater"
Donations of any sort are always welcome. So hope to see you on GB3TQ.
Bob G0AZX (Repeater Keeper) bobazx@blueyonder.co.uk
Martin G3VOF itnld@btinternet.com
********* Latest NEWS Winter 2009 *******
IO80FK
Here is a list of everyone who has helped with the project so far:
G4UTM (Brian) G4RKY (Matt of GB3FH) G3ZVI (Peter of Garex Exeter) G8AUU (Chris)
G8XST (Bill of GB3TR) 2E0FWD (Chip) G3VOF (Martin) G7HIK (John) G0UHY (Malcolm)
First of all a very BIG thank you to Brian G4UTM and Matt G4RKY. Without their help this project may never have been completed. The true sprit of Ham Radio (very hard to find these day's)
As you may or may not know we have had to do a complete rebuild on the Duplexer,as the first design turned out to be very unstable, and difficult to tune.
Brian G4UTM (who built and designed GB3FH's Duplexer) came with a new idea of using Piston capacitors for tuning each one of the stub's (4 on the TX side,and 4 on the RX side). These have to be made on a lathe from brass and PTFE. On having drawings of these and the materials, we tried to find someone local who could make these for us, but to no avail.
On having regular email contacts and regular QSO's with Brian he kindly agreed to make all eight of the Piston capacitors for us.
Matt G4RKY supplied us with off cuts of LDF750 hard-line for making each one of the eight stub's (this stuff is like 2" drain pipe),and also the double shield coax we will use for connecting each one of the stub's together.
The pictures below show the different stages of the build of each stub,right upto the finished
duplexer. LDF750 is not easy to work with,and it's not a quick process to make each stub.
Silver Mica cap's are fitted on the RX port (4 x stubs) to recover the recieve freq .
And wire wound inductors are fitted on theTX port (4 xstubs) to allow us to get max power output. The last job then was to fit RF shields to the top of each stub.
As with all Duplexers the finished item has got insertion loss 1.5 db on the RX port and 2.0 db on the TX port. Not bad really when you consider this has to null out the Transmitter from the Reciever at just half a meg.
Why build this monster you ask ?? Well simply the cost of a commercial Duplexer for Six Meters is out of this world.
*********** Building The Duplexer For GB3TQ *************
The eight tuning capasitors made by Brian G4UTM
Exploded view of tuning capasitor
LDF750 The start of building the top of the stub
Outer shield fanned out to get access to the centre core where the tuning capasitor will fit
Outer part of tuning cap driven into centre core and soldered in place
Outer shield bent back into place and soldered
Tuning capasitor fitted,and ear's bent down from outer shield to form connection point for shield side of connecting coax stubs
One finished stub with RF shield fitted to top
The finished Duplexer wall mounted, tuned, and ready to go
Tait 300 series Ex Outside Broadcast units supplied by Chris G8AUU. These crystal control units were already close 50 Mhz and ideal for what we needed.
Plus two logic units supplied by Bill G8XST
Peter G3ZVI worked his Magic on converting the RX & TX to 50 Mhz
Moonraker SQBM 1000 tuned to 50 Mhz by Martin G3VOF
The Location of GB3TQ
GB3TQ Footprint
Thank you for looking at this site and have found the text and pictures helpful and informative.
I know myself and the others in the team that have been involved in building this repeater so far have found it very much a learning curve and a lot has been learnt. Lets hope it will carry on that way and that we can all together make it even better.
Bob. G0AZX GB3TQ 2009
******* NEW Feature fitted to the repeater *****
With the growing RF polution now apprearing within the Amature Bands we had a request if it
would be possible to TX a CTCSS tone now on the TX signal of GB3TQ.
As we feel this makes good sence too,and maybe more in mobile use,we have fitted a 77 Hz tone on the TX signal.
If your radio allows Decode on recieved signals please feel free to program this on your radio.
It should read something like ENC.DEC in you program menu.And set this to 77 HZ CTCSS tone. Once done your radio will
then only recieve the valid signal from the repeater.
If your radio has not got this feature DO NOT WORRY you will still be able to recieve the repeater.
CTCSS tone is invisable and will not be heard.
****** List Of Some Of The Recorded CallSigns Useing GB3TQ ********
G0RDO G7DHW G4WZN G3UZM G4OCY M1AGY M0ZOL G4EZV G3VOF G0FGX
G4RKY 2E0FWD M1OOO 2E0PDL G1EUA G8BUR G3SDW G1OCN M0ZPC
G7AHP
Will add to this list as we go along.
This website is powered by the UK's virtual Motor Racing Site
Click This Banner To Go To This Site