Since our tower was so badly damaged in the high winds we have worked hard to split our three repeaters antennas over our two short masts. GB7WB’s UHF 8-Stack is on our damaged main tower along with GB3WE’s RX VHF folded dipole. A spare 2.4GHz Tonna beam has been fitted as well.
GB3WB’s UHF 4-Stack is on our old turbine tower along with GB3WE’s TX VHF folded dipole. Our main 2.4GHz Tonna beam is also fitted to this tower.
To keep GB7WB on the air we have recovered as much of our damaged tower as possible and fitted its UHF 8-Stack to it.
Also we are using G4KLX’s split repeater software to enable us to use two separate receivers to provide site diversity.
The second receiver is in Worle to provide some additional receive capability.
Jonathan’s software automatically selects the best GMSK data from which ever receiver provides the best bit error rate.
Hopefully this will make up for the low height of the GB7WB 8-Stack.
On Sunday Morning 29th April 2012 our main tower suffered massive damage in the high winds.
At 5.22 am the lower part of the latice tower folded which caused the whole tower to fall into a nearby tree.
Amazingly not a single antenna or feeder was damaged and even the wind turbine and blades are in perfect working order.
In order to keep all of our repeaters on the air we have moved GB3WE’s folded dipole onto our small wind turbine mast. This mast holds the GB3WB 4-Stack already, so its coverage is unaffected.
To keep GB7WB on air we have had to temporarily fit a colinear to the very short remains of the damaged tower, so it is practically at ground level. Obviously coverage will be well reduced, but at least GB7WB is still on the air.
It was a very big and dangerous job to get the whole tower and turbine out of the tree. But to make the area as safe as possible as quickly as possible we have worked on the site more or less night and day for three days in some terrible weather conditions.
Here are a selection of photos of the damaged tower.
GB7WB Fan Control Thermostat Modified & Fitted.
The thermostat we had only had a ‘normally-closed’ contact and we needed a ‘normally-open’ contact to put the 24v fans on when ever the repeaters got too hot.
With three FX5000 repeaters stacked on top of each other, with their six combined crystal ovens and three power amplifiers etc you would be surprised just how hot they get!
A grub-screw was removed which was fitted to provide a rest for the center contact of the bi-metalic strip. A small screw with a solder-tag and wire was used to replace the grub-screw and the wire was attached to the spare solder post.
Now we have a single-pole, double-throw set of contacts and the fan switches on when the temperature rises.
GB7WB & GB3WB Both Using DV-RPTR Modems For GMSK D-Star.
Both of our D-Star repeaters have now moved over to DV-RPTR modems and are controlled by Jonathan Naylor’s latest beta software.
Get more details of the DV-RPTR modems here: http://www.dvrptr.de/
Find out about Jonathan’s G4KLX repeater software here: http://db0fhn.efi.fh-nuernberg.de/~g4klx/ Both repeaters are operating better than they ever have and don’t suffer from any problems.
The GB3WE VHF repeater suffers tremendously from ‘metal-on-metal’ interference as all repeaters do. This interference is noticeable on any weak signals accessing the repeater and sounds like a constant crackle and almost as if a microphone has been placed next to two pieces of metal while they are being rubbed together!
This is caused by the repeaters transmitter constantly transmitting its energy into all nearby metal objects and the receiver being able to detect the making and breaking of any conductors which are allowed to freely move across each other.
Every conductive object must be either securely fixed to any adjacent conductive object or insulated completely from the other objects, the important thing is that they must never rub together.
Our guy wires were our biggest problem, so we had to devise a way to insulate them from the tower and each other to remove the interference that we were suffering from.
It didn’t help that we have a three section wind-up tower with a very heavy wind turbine mounted on the top, which caused the tower and guy wires to move continuously in the wind!
Cutting the Gordian knot! ….. The photos show how we overcame the problem.
Here is a short video to show you how bad the interference is when a weak signal is accessing GB3WE and metal objects are allowed to rub on the guy wires
In the tremendous winds of the morning of 05/01/2011 at 1am the tail was broken off of the GB3WB wind turbine. This had the disastrous effect of stopping the turbine from auto-furling.
This left the blades facing the wind, which caused them to spin at thousands of RPM until they were all broken off. This is a disaster for our repeaters.
It is worth noting that our modified oil-filled heater 24v dumpload worked perfectly day after day and saved our expensive battery sets from over voltage charging and burning out.
Other repeaters running from wind turbine power not so far away lost their dumpload, which in turn destroyed their battery sets. They also lost their mast and antenna. It was a real nightmare for us all!
We have currently turned off the repeaters to conserve the power in the batteries.
A new tail and set of blades will have to be bought and fitted asap so that the repeaters can be activated again.
Click on the play button below to watch a video of what is left of our turbine.
GB3WE GB3WB GB7WB New Configuration. GB3WE & GB7WB are ircDDB STARnet Digital Group Calling enabled D-Star repeaters.
GB3WE is the top mounted dual-mode VHF FX5000 D-Star GMSK/FM repeater.
GB7WB is mounted in the middle and is a UHF FX5000 D-Star GMSK Node.
GB3WB is mounted at the bottom and is a UHF Key Repeater for FM.
GB7WB Modifications to FX5000 Transmitter For D-Star Operation.
To modify an FX5000 VHF or UHF for D-Star GMSK operation simply add a 47nF capacitor across C493 (22nF) which is next to IC403 (TL072) in the transmitter driver module.
Then remove C536 (10uF) which is next to IC504 (LM324)
No modifications are necessary to the receiver module.
Wireless DoorBell Mixing Interference Shown BY G3SDH.
Due to the terrible wideband local oscillator in the cheap wireless doorbells we are finding more and more cases of transmissions appearing on frequencies where they shouldn’t be. In fact it turns out that any 70cm signal can easily be mixed by the doorbell and the original signal can now be found somewhere else in the band as well.
GB3WB Wind Turbine Modifications. The GRP blades have now been balanced. New tail pivot spring brackets have also been fitted. A second 12 way slip-ring has been fitted inside the main 3 phase slip-ring so that other equipment may be fitted onto the turbine to monitor its preformance or send other data. At the moment LED’s have been fitted to each circuit to test them.