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02/10/2021 GB 7 IV PROGRESS

Update on progress of GB7IV, this has been a long haul project due to problems getting a suitable set of duplexer filters, these filter allow us to connect both the transmitter and receiver to a common aerial, which has all ready been installed, and is visible in the site photographs.

To get GB7IV on air from SMC Chandlers Ford, Chris G4HCL and Andy G4MYS We were able to borrow the GB3SH duplexers, which have been returned, and thus SH is available and on air. Chris G4HCL tracked down what seemed to be a suitable set of filters from North east England and brought them down to Whitby and Andy Went and got them from Whitby, the place famous for its oddball connection to the North Yorkshire moors steam railway as much as its beach.

Unfortunately the supplying repeater group were not are that the filters they sold us were totally unsuitable, the markings indicate they were, being as they are on the 220Mhz band great for a 74cm repeater in the USA, but not here in Blighty!

So we set about trying to convert the British Gas filters were got given by then some 10 years ago, We were then fortunate to get brand new old stock Sinclair duplexers from SMC which we clubbed together to obtain, which also promised to work, but tests quickly showed they played up if they were operated with more then 2 watts - not very useful!

The state of play currently is Alan G8IPG is working on getting the British gas filters to work with the Sinclair filters to have enough "notch" which is more then 60db per channel ( Tx & Rx ) One filter is in situ and is connected to the test transmitter in site a Tait TM8100 so show we can operate a GB7IV without problems to GB3SH, and this is so. The test beacon of GB7IV is a sent around every 7.5 minutes and is running the ERP of the licence, it sending: GB7IV TEST.

Soon We have have all the filters on site, and then we will be able to connect it to the repeater and test as a repeater, that will be soon be not yet, this GB7IV will be a C4FM unit, capable of connection to the internet as soon as we can get a stable reliable internet connection available to us, It will not be connected to Either MT or PO. In this way we will be providing 4 separate repeaters from site each with its own unique identity and possibly user base.

At a later time We will run tests to examine integrating GB7SU to site, as the site offers many advantages to the DMR users over the current site.


Our engineers have been to site again to sort out the lacks of pips on both GB3SH & GB3SU and is common with most of these things, a common problem was harassing both repeaters. Simply put RF energy was getting in to the area that the logic is in, and more importantly on to the DC supply cable, and the simple cure was to wrap the DC cable through a ferrite ring several times both cured and a lesson for us all in areas of high RF field stop RF entering electronics with RF filters !

The camera and weather station are back after engineers for there respective companies who run the internet and wifi system We rely upon worked on the cables and the distribution system, and found the signal to be around 6db below a working level, while We cannot say exactly the cause, we know someone there has shifted much, and has got favours done to get us and our camera -back on and We say a big thank you to Peter & Dan. It is good to know our supporters help us in different ways.

Other problems were looked at too esp the " coaxial experiment " which will be done on another day.



Work at the repeater site continues: with GB7MT being refitted after a PCB replacement after a connector failure on the rear Panel. ( Andy got the blame )
We have also fitted the GB7IV beacon,( 145.775MHz ) currently it's sending " GB7IV B" on FM every 7 minutes, this is being done at full repeater power to show and prove no interference to GB3SH receiver.

GB7IV is of course a Digital repeater and will be using C4FM / Fusion when it comes on air. This repeater GB7IV we fully intend to connect to the wider Fusion system!
The work is long and tedious due to us not being able to afford brand new duplexers at some £1,800 per set, Its a real pity we cant get the old GB3PC unit as this was all ready on frequency!...

We were able to get a new but under powered duplexer from the well known Sinclair manufacturer in Canada, which we got at an amazing discount of just £400:00, as "new old stock", We had to bring it down from of all places the Marine band!... and We thank those who kindly chipped in to funding it. The problem: We soon found is that it would only handle about 2 watts!, before playing up.

We have thus been carefully working on introducing two more 8" by 3ft high filters, loving supplied / Scrounged off British Gas some years ago,.. One each for the receiver and transmitter, to enable the filters to handle the full 17 Watts.

Additional work is being done to our DC systems to ensure a " fail to battery" goes smoothly, with each output DC port having its own relay, fuse, and fuse fail indicator, additionally an easy fit battery "2" has also been introduced, for when we have an extended outage.

Off board battery chargers have also been introduced, ensuring a recharge of the batteries, and maintaining a healthy float voltage.
We are still investigating the blocking experienced by GB3SU when GB7MT is transmitting, currently commercially made filters by "Procomm" at several hundred quid each have been added to the receiver of SU, and the transmitter of MT , and as some of you know we still suffer de-sense, problems.

Research made by Alan G8IPG, and confirmed separately by the keeper of GB3IW: G4IKI indicate that our coax may be the seat of the problem. We should be familiar with what happens if you put a diode or even an accidental diode across an RF circuit, in repeater systems rusting bolts on the guy lines, and other nearby metal work can become diodes, rectifying the RF, and making a broad band clicking and noise.

So now let us turn our attention to the installation: having proved the GB7MT transmitter is squeaky clean, and that the circulator's have cleaned up the incoming RF to the SU receiver, but the QRM persists, we need to look at other parts of the repeaters installation.

We use quality commercial grade low loss coax called: LBC 400, on the length we use this is a good compromise between sheer cost per meter, performance, coupled with and plug cost, about a fiver each, the coax too was around a fiver a meter, and half the loss of RG213, its a good choice for us! However research asks the question - or is it?

LBC 400 has an inner core of stranded copper, a solid dialectic, surrounded by "bonded" aluminium foil, which of course has the current carrying copper braid around that, and the outer " weather proof jacket" around that. This is common design for quality cable, be it TV or communications cable. With TV of course its not carrying watts of power, and of course at our homes We don't have a sensitive receiver connected to the same aerial! So such coax at home is great its quality and low loss, a tad expensive, so where is the suspect problem?

This is with the different metals of the aluminium foil and the copper braid, ( this is not 1st April joke BTW ) which under certain conditions have been shown to create a diode effect,.. a very low level broad bandwidth RF noise can be generated, small enough only to be heard on nearby receivers, and too small to be detected more then a few feet away! the cure is to replace the coax! So hands up who wants a lot of very high quality coax then?!

Further research shows that even the connections between the RF plugs and the coax can, and does cause problems due to the different metals used!

Thus coax replacement needs to be a fully copper system, such cable is known as "hard-line" consists of usually a tube, for the inner line and a almost copper pipe as the outer, its available in different sizes from around 12mm to whatever at megger quid per meter and about 25 quid a plug!... We further understand that many RF sites only permit the use of hard-line cables, there must be a reason why!

First however we will do an experiment, at a time to suit a team will go to site and run out two 33M lengths of fully copper RG 213, two aerials and see what happens!

We'll let you know when this experiment happens, its likely to be a Saturday or Sunday afternoon as we got to be off the roof by darkness!

We will need some not scared of heights on site ( we have keys to the bog on site, ) and amateurs on air: , locally, and DX stations too, - so are you in for a true amateur radio experiment?

Dont worry we wont change the aerials or coax that day, this will be a prove / disprove experiment only with the aerials stood only on transportable tripods.
comments shedding light on this subject are welcome!

The committee


We are considering removing the Broadcastify facility due to lack of use, and on going interruptions of service.

Rather then switch off straight away, We are considering turning it off on 30 Sep 2021, as this is a remote off air receive facility only service, discontinuing it will in no way effect the operation of any of the repeaters.

We are grateful to the loaners of the equipment used, and that will be given back directly to them soonest after 01 October 2021

Andy G4MYS


We are pleased to say We have started on upgrading the DC supplies, Battery charging and the DC PDU ( Power distribution unit ), in addition We are building a 24 Volt Power supply with battery changeover unit, this will provide a long battery back up in time of AC power failure, for the 24 Volt equipment, More on that later.

Today We tried to swoop the loan GB7MT out for our own, but the equipment suffered from a Mini USB socket mechanical failure, thus the Repeater is now on its way back to YMUK for repair.

This we still have the loan unit on air as GB7MT and as such there is no change in MT behaviour.
However this did not stop us fitting the Beacon for GB7IV.

The Beacon is on air, though its duplexers and one filter, as We wanted to prove that we can run two VHF repeaters on one site with out mutual jamming either way.
The tests preformed today indicate this is the case, We will find out more after fine tuning in a few weeks time.

The tests are a beacon which appropriately is every 7 minutes and sends at around 14 WPM the following: GB7IV TEST
Power level is around is targeted at the Licensed power output, however there are losses in the system, and this is confirmed by the SUWS monitor ( which shows the beacon as around 5db in signal lower. We are of course interested in reports of the RF signal strength at your location Reports too:

The equipment an ex commercial PMR radio: Tait TM8110, the repeater Duplexers from SINCLAIR, and one filter ex British Gas, the aerial is the purpose fitted dual band colinear attached to the top of the GB3SU aerial mast.

Today We extend our thanks To

Alan G8IPG, Andy G4MYS, David M0XIX, Bill G0XAZ, who were directly involved, and several others who helped on the day with reports and moral support!

Next time We hope to address the sensitive issue with the duplexer this is likely to be Sunday 25th.

Unfortunately, the Thames Valley Repeater Group (TVRG) has to announce that the GB3AW UHF repeater located 7 miles SSW of Newbury, at Ashmansworth. in Berkshire will be moving site. The existing site at has been sold and is being developed. We have managed to find another site fairly close at a similar height. There is a fair amount of work to be done, taking down the existing mast and erecting a new one at the new site. The equipment is being rehoused to occupy less room and it is probable that the logic will be different.

Timescales at the moment are flexible but it is most likely that the existing GB3AW will go "off-air" by the end of July. When it returns is dependent upon on a number of factors, not least when we receive approval from OFCOM for the move. Although the new site is fairly close to the old one, the distance is such that it has to be regarded as a new repeater application. Having said that, we would do not expect there will be any problem is obtaining approval. As a guess, we would hope it could return by the end of September/October.

An application for the new site was submitted yesterday.

GB3AW has been on air from the present site since 1978 and has been run by the TVRG since 1992. Still all good things come to an end, and we hope you will find the "new" GB3AW useful to you.

Chris, G4CCC.
Thames Valley Repeater Group.

P.S. GB3RU is currently off-air. We're investigating why this is.



It does not take us long to do an upgrade, suggestions made at the Southampton Amateur Radio Club meeting last Wednesday,. were put in to another IC, and that was fitted into GB3SH on Sunday 21st June.

This modification to the M0XIX logic tells us importantly if we are running on batteries, also The speed of the pips and CWID has been changed slightly. Thus as you have noticed the end of each over we get in normal conditions pairs of pips. However when running on battery's we are greeted by a " B " in morse. Problem for us of course the " B " also is an indicator of our CTCSS tone. We also need to know even when the repeater is idle what is going on, thus when GB3SH beacons every 15 minutes when idle running on either AC or DC, it sends "GB3SH B" should it be running on batteries them another "B" is sent in a different octive ( tone ) to alert us to its operational state.

The GB3SU logic is currently a Zetron Model 38A, which is odd school commercial repeater logic, which is why it sends up to 4 pips and only CWIDs during overs. We will introduce M0XIX logic onto GB3SU soonest. Alan G8IPG is working on GB7IV duplexers with a view to getting it on air soonest. He is making progress tuning the brand new SINCLAIR duplexers and old British Gas filters to allow us to run GB7IV at full licenced power.

We like to thank in particular David M0XIX for his attention to detail in producing the new logic for GB3SH, as this is around the 7th one he has made!
Many thanks to: David M0XIX, Alan G8IPG for fitting the logic, and Andy G4MYS for working on the DC electrics and rummaging inside the racks.



Another visit to the repeater site, resulted in MT being off air for 2 1/2 hours as SH was removed with its integral power unit which also charges the batteries. Another SH has been fitted, see picky 1312, pictured here while being built with the yet to be fitted GB7IV duplexers.
This repeater has the M0XIX logic inside it , and this logic has some special features:

Time out is ( as per also on GB3SU ) is 4 minutes after which your over is marked with time out pips to let everyone know you have timed out,.. total time out is 8 minutes, if you rabbit on that long SH will chuck you out and close down. This feature is to prevent jammed PTT holding the repeater open for hours, this same feature exits in SU also, that's the way We ( G8IPG has ) have programmed them.

SH sends a distinctive "double bleep" at the end of each over, and access. However and but, should we have a power fail, then instead of the double bleep the Repeater will send a "B" in Morse ( _...),! at the end of an over, this repeater is a stop gap machine, ... the revised and yet to be fitted repeater will have a modification to the CWID to indicate loss of AC power, which will be a double B being sent in the CWID the first one being the code for 71.9Hz CTCSS, and the second being "Were running on batteries!"


SH is running on a stop gap PSU too, to which were thankful to Chris G8BAL, this goes to show a little " maas " switch mode 22Amp PSU force cooed by a fan, can run our repeaters for 1& 1/2 hours continuous transmit when push comes to shove ! If there is any doubt in the capability of these little wonders we doubt no more. We understand Nevada flogs them.
The temporary GB3SH is built from two ex PMR service converted Tait TM8510 transceivers, they generate the CWID, which is also sent with the CTCSS in encode, we cant do much about that, however once again this rule only applies to this stop gap unit.

Also fitted was a beefed up battery charging unit, which will enable faster recovery time when We have a fail to battery event.

GB3 SU picky 1421, taken of the fitted unit and its logic, in the rack, was also changed out this visit, a pair of Tait UHF TM8110 which have been in service for around 3 years total, was replaced by a rare brand new old stock 1U height Eclipse Repeater, a lot of time was spent on this unit by both Andy G4MYS and Alan G8IPG, who unlocked its secrets,...this is driven by a brand new old stock commercial logic a ""Zetron 38A" which has been programmed with a similar behavioral patterns as SH, the end of over, however is followed by Pips. A number of pips at the end of an over, unless its due to send its callsign which is every 15 minutes, and is rather fast, in this way by listening to the speed of the CWID you will be able to tell which one has beaconed. ( SU is fast , SH is slow ) Otherwise 3 to 5 pips will be send the exact number is down to what "state" the logic is in, normally its 4. Thus in normal use you will get 4 pips or a callsign at the end of an over. Once again this SU is not a permanent replacement, We have removed the other one to upgrade its Logic to the M0XIX type with its expanded facilities including the Running off batteries alert! The CWID is sent without CTCSS when its in beacon alone mode, this is because on a commercial repeater the CWID is generated in the logic if required ( in the USA ) not the transmitter unit as
The repeater removed will be upgraded with the M0XIX logic, we will then use the best behaving repeaters on air and keep standby units ready for action.
Our thanks is extended for his patience with us, and his knowledge of microchip abilities to David M0XIX
For metal bashing and soldering Andy G4MYS
For programming the most awkward 1980s designed logic and excellent RF knowledge Alan G8IPG
it is of course team effort the whole thing does not come together without the efforts of many, and we thank you all for donations and gifts.

Weather camera..As a result of all the unplugging the mains we lost the camera output for some time as this takes up to 12 hours for some unexplained reason to re emerge after a power loss, we are looking into power this with battery back up.

That Tv aerial you'll recall We removed the fallen TV aerial from the roof, the pickys here explain

Picky 1424 is the installed aerials as is 6 June, The disused top aerial is what remains is still up, the middle and front section of the failed aerial, below is an upside down TV aerial the one in use, its normal to fit the cable connector to the top of the boom, thus keeping rain out!

Picky 1428 is the fallen section, we were interested to show you the fractured boom which is the failure point

and the amazing amount of rust on the aerial connections, picky 1426.

We checked over all the masts wall mountings on site, ours & SCC, and all appear well after the long winter and its winds.

We were blessed with good views today a cruise vessel P&O Iona Ocean Terminal is in the old docks picky 1418

02/06/2021 THANK YOU

Thank you to Geoff G4ICD of RF Comms supporting the S.H.R.G.

Check out his page, we have just bought over 4000 cores any many top grade materials at silly prices WWW.RFCOMMS.CO.UK

G4MYS onbehalf of the group

Radio Spectrum
New proposals to help people boost mobile signals indoors

People struggling for a mobile signal indoors will be able to buy a wider range of 'mobile repeaters' under new proposals published by Ofcom today.
Indoor mobile repeaters are devices used to boost a mobile signal and are typically used in residential properties. They can help people and businesses who struggle to get good mobile reception indoors.

In 2018 we authorised the use of mobile repeaters, so long as they met certain technical requirements. We are now proposing to amend those requirements, to extend the range of devices that people would be able to purchase legally. This would provide more choice for people who are looking to boost their indoor mobile signal and potentially bring down the cost of devices.

We are also consulting on proposals to help make it easier for people to see which devices meet the technical requirements and are therefore legal to purchase. This would help to prevent people buying illegal devices, which could cause harmful interference with other wireless equipment.
The consultation closes at 5pm on 28 July 2021.

02/06/2021 Radio Spectrum
New licence condition for spectrum licensees confirmed

Ofcom has today confirmed a new licence condition that now applies to the vast majority of spectrum licensees.
The changes mean most licensees will need to take action to ensure their equipment operates within international guidelines on electromagnetic fields (EMF) for the protection of the general public. Most licensees will also need to keep records demonstrating their compliance.

Following the publication of our policy statement on EMF in October 2020, we wrote to licensees in March this year to inform them of our proposals. We have considered licensees' feedback carefully and made some changes to the new licence condition and guidance documents. Today we have published full details of our final decision on the licence condition.

We have also published guidance on what licensees should do and how long they have to ensure compliance - this is dependent on the frequencies they are using. Our EMF compliance flowchart tells licensees whether or not they need to take action and, if they do, what action is needed.

A simplified version of the full guidance and specific advice for holders of amateur, ship radio and aeronautical licences will be published next month.
We will shortly be writing to affected licensees to inform them of our final decision and provide a replacement/update for their current licence.


Alan and Andy have been back to the repeater site with the intention to rid GB3SU of the QRM from GB7MT once and for all time, the result of this visit was plenty of test tones on GB3SU from the test set as they tried various filter configurations on GB3SU and GB7MT. Basically whatever was tried did not really improve the situation. In the process GB7MT was put back on its 4 stack UHF dipole array, and this made the situation worse, so its back on the GB7IV colinear!

We fitted a "circulator" to the transmitter of the effected repeater: GB3SU,
A circulator is a passive, non- reciprocal three ( or four-port ) device that only allows RF signal to exit through the port directly after the one it entered. "Ports" are where Coaxial cable or coaxial couplers connect to the device. For a three-port circulator, a signal applied to port 1 only comes out of port 2; a signal applied to port 2 only comes out of port 3; a signal applied to port 3 only comes out of port 1, and so on, therefore form our point of view the circulator acts as a one way street!

While it may seem a little crazy to fit a filter to the transmitter of the effected repeater,.. one would think rightly so that filters need to go on the effected receiver, one needs to bear in mind that RF will also go down into the transmitter of nearby repeaters ,.. in here.. the transmitter of GB3SU.. whether it is transmitting or not, the high powered unwanted RF can cause problems by "mixing" inside the transmitter, and it was this signal we were seeking to reduce., So we fitted a circulator, the drawing explains what happens. In this drawing Port 1 is connected to GB3SU Transmitter, and port 2 is connected to the coax which goes to the duplexer. Port 3 is connected to a 50 Ohm dummy load rated at the same power or more then the transmitter. Thus any RF entering down from the duplexer on port 2 is dumped by the Circulator in to the dummy load on port 3. In this mode its known as an Isolator. The working of Circulators are not covered in the RAE, and you can see why normally we have no use for such a devise, they are big enough to sit on the palm of your hand, are heavy for size and at UHF around 5MHz wide, they also need careful tuning, however very important is not to drop them as they contain ferrite material.

The circulator has not cured the problem completely to the frustration of our lads, and the users, no doubt, however the Lads will go up gain with other parts to try and work out where the problems is and how to cure it!

They also fitted a circulator to GB3SH to try and rid ourselves of the data QRM from the co sited SCC system, hopefully that will do the trick. We will only find out as the week goes by as We cannot stimulate the SCC transmitter in to operation! ( and rightly so )

The other important work was to test the all brand new GB7IV, this is built form a pair of "New" old stock Motorola GM360 mobile transceivers, they have been fitted in to a 3U 19" rack tray, the idea today was merely to check that they would work together successfully side by side without miss-behaving in a repeater set up. Users were puzzled by the behavior of "GB3SH" as it gave no pips or callsign, and had a squelch tail! - as of course its to be fitted with a Raspberry Pi and other electronics to allow it to become a data repeater on R7, 145.775MHz. We will tell you more as this project progresses.

The other important job was the first one we did, as the wind was low at the at time, as during the last few days we have had storm after storm with high winds cross the United Kingdom since the start of May. On the 3rd of May our on-site weather station recorded a peak wind speed of 72.5 MPH. The following weeks saw high winds for this time of year, Thursday 20th had a speed of 65.1MPH, during all of this an abandoned TV aerial which was left in situ, was unknowingly about to fail, curiously the fitters who put the new one up last year simply cut the coax to it, and connected that coax to the new one further down the domestic aerial mast and left the old one to its own devices. Friday afternoon shortly after 1300 the rear half of that TV aerial fell off!, landing fortunately on the roof, and rolled into view of our weather camera! As the windspeed this morning were low enough for us to access the roof and check our aerials and the others, Alan Recovered the rear half of the aerial before it went any further.

So why had it fallen? This TV aerial is the type which sits on a twin support boom, the clamps on the boom grip the aerial l towards the front, and rear, the rear one is where the aluminum of the boom has fractured and snapped. As to why? The rear section has a 20 element reflector which is also clamped on the the boom, this had worked itself lose and was able to rattle itself back and forth along the boom for around 30mm, Why it was taken out of use? - We will never know but - the F plug aerial connector had no weather proofing!

09/05/2021 SITE VISIT & CHECKS

Alan and Andy made the first visit to the repeater site this weekend and found one little problem which was causing QSB last year, with GB3SH.

Oddly enough only one station, 2E0ZBE reported QSB from GB3SH last summer, and it was noted then that the power level was going up and down, this could be clearly seen form the trace of the Farnham SDR. With gratefull thanks to them for their useful facility.

The cure to this was to plug in the cooling fan Tray DC connector which had fallen out of it's socket, so we now know to screw up those silly D plugs dont we ?!! The reason for the QSB was the PA was getting hot and automatic thermal protection was kicking in and the effect was the Power was being turned down! The fan runs on the transmitting being activated, and it runs on for another 3 minutes, after the tx goes off air.

We refitted the filter which should keep GB7MT out of GB3SU receiver,... all be it not as well as we'd like, Both Alan and Andy have been on the trail of more Narrow notch filters to try and keep one repeater out of another.

Additionally measurements were taken so we can make up new coaxial cables for extra filters for the VHF digital repeater GB7IV, these filters will enable us to test GB7IV at full power hopefully before installation.

While They were on site the winds were reaching 59.9MPH, they watched our aerials from the ground, moving with the wind.


Were sorry to report that there is a failure in the link somewhere which has downed our system.

We have good reason to believe that the problem exists with the Internet supplier who are changing cables and equipment in their network, this may be also associated with a vandalism attack on their equipment in the city centre, on Monday 12th.

We are aware that our camera and weather station went down at 00:07BST on Monday 12th April 2021, at time of writing We have no news at all, of when we can expect a re-connection. GB7MT will operate as normal as it uses a Microwave RF link to GB7PO.


Were pleased to say were back!

Our logging kit records we returned at 1354Local Wednesday afternoon.



Due to Covid restrictions we were unable to do the raffle on the date last year at The Southampton ARC Meeting.

We followed FULL Government Guidelines and held the Prize Draw on the Southampton ARC Zoom Meeting.

Well done to the winners of the prizes and thank you to you who purchased a ticket. The profits made go in to the running of our repeaters.

1st Prize - FT70D (Ticket 356) G8XIX Cheryl

2nd Prize - Alpha Tronix Power Supply (Ticket 351) G7NKZ Keith

3rd Prize - High Power Glass Insulators (Ticket 377) M0VBD Rob

4th Prize - Ceramic Insulators (Ticket 3) G8IPG Alan

Thank you for your support. The Committee



Behavioral Tests were made on Saturday 6th March to establish if our "Sinclair" Canadian built duplexers would work successfully on the 2M band.

These test followed others where the D Star repeater would not behave and We were seeking a second test to try theory's out.

We tried with an Icom Repeater "GB7IV ", between 0800 & 1130 also Yaesu DR2 " fusion" type repeater, from around 1200 to 1800L and a pair of Tait TM 8110 mobiles which will form a complete standby GB3SH. from 1800 to 1845L

The tests used in D star, C4FM and FM this allowed different modes to be tested and with FM other non digital users could try it should they have wanted.

The tests consisted around attempting to run the transmitters at different power levels, with in the licence limit, to establish if the transmitter was happy and also importantly if any De sence was happeing, in other words if the transmitter was deafening the receiver, It difficult to establish this with the D star repeater as it wont run FM and neither does it have an S or RSSI meter. But what We did find out was that even at 17 watts our limit the D star repeater was happy.

After lunch it was the go of the Yaesu DR2, We put this in to dual mode, and found out how it operates in dual mode configuration. For the record it only sends its CWID on FM, and it will wait for the end of an over to CWID in FM, however when its time to CWID and its idle, even if the previous QSO was in C4FM, it still goes over to FM and sends the CWID. One or two may of had the surprise then of hearing " GB7IV " as a CWID and may of wondered wat's that?! This is when We started to note the desencing issue, while We were playing on FM.

In the evening We tried the Two Taits bearing in mind : We have had them at the repeater site on air behaving impeccably at 17 watts as GB3SH in to the SH duplexers without a hint of problems for several hours.

These Taits also played up when used on the IV channel and the IV duplexers, curiously it was beaconing as " GB3SH" of course,.. and anyone puzzled by finding a "GB7IV" in the afternoon must of wondered how GB3SH had QSYed! and perhaps even better why there was now two of them!

So the conclusion is........
As three different repeaters from 3 different manufacturer's played up shows that the Sinclair duplexers are not up to the job currently.
What to do about it is of course being pondered as We of course do not want to be restricted to 3 watts from the transmitter !

As for why the D-star repeater played up previously, it is just possible that as the twin screened RG214 cables were a very precise 319mm long, this precise measurement is the length of coax links fitted to 145Mhz duplexer cans, it is possible that this alone caused the problem as during tests with the D-star repeater again today it did not misbehave.

So were glad We tried off site as it is more easy to fathom out what is happening when not working in the restrictions, of the repeater site be that the COVID Threat, The cold, it struggled to get above +5C today! And of the dragging all the kit to site in the first place.

We gratefully thank:

2E0TGE 2E0ZBE G4MYS G6DLJ G7AFN G8IPG & M1PVF for working through and help test the repeater system.

Thanks to: ICOM Yaesu and TAIT for some rather good radios to play with!


The Yaesu DR 2 from the tail connections note "callsign" GB7MT on the repeater, and "GB7IV" on the duplexers. The DR2's are dual band so it was no problems to reprogram GB7MT to become GB7IV!

The almost complete standby "GB3SH" on GB7IV channel just before its "go", sitting on top of the on air DR2, the top unit is the monitoring unit showing volts and current drawn, also holds the RSSI or S meter and a convenient " tx test inhibit and normal" switch on the front panel, and the electronics to enable the operating "On Battery " ident to be transmitted. Also fitted a thermal probe on the transmitter heat sink, with its display on the panel, this curiously worked from two 1.5 volt button cells in parallel !


New 145Mhz duplexers work very well !!
New build GB3SH repeater functions well !

We are pleased to say our desire to have a fully spare working VHF FM repeater ( cold standby ) has been built with Tait TM8100 mobiles, built in New Zealand, it's been soak tested in to a dummy load for several days, for thermal reasons, and tested on air, with the logic, a brand new design by M0XIX to our specifications with some features for ease of use and information. For instance when running on battery back up, a special tone will replace the end of over "Beat". This repeater has been tested with our brand new old stock Sinclair Canadian built Duplexer which was aligned to R7, 145.775 Mhz by Richard G4WFR.

The next thing to do is take them to site and air test both of them on our aerials. A date for this has yet to be decided as with everything its COVID dependent.
While the repeater is intended to be a fully spare GB3SH, that we can take over to the site and remove the fitted unit and fit this one with, it will be tested as GB7IV on the IV channel. This will enable us r to find out if We can run two VHF repeaters on the same site at the same time. GB7IV will of course be a data repeater, We want to try both Fusion ( C4FM ) and D-Star, it is however more easy for us to test with FM, and even We have plenty of FM handhelds which are easy to test with!

We will let you know when We do these tests as we will need as many as possible to engage in QSO's to ensure equipment compatibility with out resorting to using even more filters.




After around five years of trying to get a set of working duplexers for GB7IV, a brand new set has been successfully obtained privately.
This gives us the desired opportunity to run a digital repeater on VHF. Once our engineers can get access to the repeater site, due to COVID restrictions, We will take one of the spare FM GB3SH repeaters and set it up as GB7IV on the GB7IV channel of R7:- 145.775MHz, and basically see if we can get two repeaters to function on one site without problems!

We will need your help with this experiment.
The experiment will use the aerials which we intend to use, as they are already fitted!
We Will of course let you know as to when We will run these tests, as those tests can only go on for a few hours at best, due to licensing, and We will want QSOs to go through both the repeaters at the same time!

You will not need special equipment, for these tests, just a FM transceiver on either the usual GB3SH channel, or a transceiver on 145.775MHz FM, the old GB3PC channel with CTCSS on 71.9 Hz. on transmit.

GB7IV will have CWID with the callsign GB7IV for legal reasons, and your interest, as normally of course GB7 callsigns are only assigned to the digital service. If you would like to help with the purchase of these filters please contact: on info on how to help with this privately funded project.

In addition We are pleased to announce that Richard G4WFR, the keeper of GB7SU and his digital DMR repeater station, which was close to Southampton docks, has joined the SHRG with his repeater:- GB7SU which is currently in West Southampton. The opportunity will be taken, to test to find out how we can successfully run the DMR repeater on our site! Once again We have the capacity aerial wise, and duplexer / filter wise, to run GB7SU from our repeater site hopefully, without interference with a much improved coverage for the DMR users.

We will on our link pages put information on how you too can get operational on DMR, the kit to use, where to get equipment from, and to avoid how to get the radio programmed,and how to obtain the needed
"Digital ID" for which a pdf of your Amateur licence is required

In the meantime keep a watch on this site for more information



Since the Covid outbreak the Southampton ARC holds now a regular get together on Wednesday Evenings at 19:30 on Zoom Meeting.

Very informal chat at times has gone on to almost midnight. But you can come and go as you please. You can hear about the latest repeater news GB3SH, GB3SU, GB7MT & GB7IV

Topics range from projects sharing of information, to subject not radio related but a good chat always!!

Everyone is welcome from Licence to SWL and those interested to take on the courses to become licenced.

Feel free to join us at anytime on a Wednesday evening, You dont have to be in Southampton some of our regular visitors log in from all over UK.... Maybe overseas soon?

For the Zoom access code e-mail Andy G4MYS at


17/01/2021 Amateur Radio history story from the BBC


We are pleased to announce that our GB3SU & GB7MT Broadcastify links are back on and connected up. The GB3SU link has been back on for around 6 days.
They were moved due the pending loss of the needed internet connection at their previous location. The new location is in a high signal area, hopefully this will improve the recovered audio especially on GB3SU, and reduce the QRM on 70cM.

Changes will be made to the aerials used over the next few days, which may interrupt the service for a while esp on GB3SU. Reports are welcome, esp on audio quality which we know is not BBC radio 4 quality to:



The weather station returned online today at 16:00. The Weather Cam is still off line and should return in the next 24 hours



Update: An engineer is on the way today to fix problem in West Southampton

We have lost our Video camera and Weather feed thanks to a fault on internet provider network which occurred at 1101AM on Monday 28th of December, which affected the Millbrook, Maybush and Shirley areas of Southampton.

While the fault in the network has been cleared, it has the effect of this has knocked out our connection to the internet. This fault is a variation on a theme on around 50% of the reason's as to why we lose connection, some of the faults are to do with the linking equipment, all of this as such is is all out of our control. Due to the COVID restrictions We can't go to our site to make our standby alternative arrangements work - frustratingly.

Unfortunately as this is late December, and many are on leave, We seem to have little hope of any any improvement and a return to service of the weather station or a viewable camera until Monday the 4th or later on in the week. However We are pleased to say our internet free link to GB7PO works fine, and this is the reason why we dont use the internet for this link!