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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.
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.
Also fitted was a
beefed up battery charging unit, which will enable faster recovery time
when We have a fail to battery event.
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.
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
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.
REPEATER SITE WORK SATURDAY 22nd MAY
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!
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.
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
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.
WEATHER CAM & WEATHER STATION DOWN
Were sorry to report
that there is a failure in the link somewhere which has downed our system.
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.
FT 70D RAFFLE
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.
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
GB7IV UNDER TESTS D-Star / C4FM / FM
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
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!
IMAGE TO OPEN IN FULL
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!
IMAGE TO OPEN IN FULL
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 !
SPARE REPEATER & DUPLEXERS
New 145Mhz duplexers
work very 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.
GB7IV DUPLEXERS GB7SU DMR
After around five
years of trying to get a set of working duplexers for GB7IV, a brand new
set has been successfully obtained privately.
We will need your
help with this experiment.
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.
SOUTHAMPTON AMATEUR RADIO CLUB & REPEATER GROUP CLUB NIGHTS ON ZOOM
Since the Covid outbreak
the Southampton ARC holds now a regular get together on Wednesday Evenings
at 19:30 on Zoom Meeting.
Topics range from
projects sharing of information, to subject not radio related but a good
For the Zoom access code e-mail Andy G4MYS at GB3SHSU@gmail.com
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.
WEATHER STATIO0N UPDATE
The weather station
returned online today at 16:00. The Weather Cam is still off line and
should return in the next 24 hours
STATION & CAMERA
Update: An engineer is on the way today to fix problem in West 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.