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Written by John Berry, GM8JBJ
Many members will remember the phone patch - the forerunner of mobile phones.
In one example, ships at sea would call Portishead Radio on HF and ask to be connected to a landline number. Once the landline subscriber answered, the ships radio service operator would flick a switch and a husband would talk to his wife, or captain would talk to his or her port agent. It was an essential service.
In another, an Aircall, Securicor or BT - mobile user would selcall their service operator. On answering, the mobile user would request connection to a landline. When the landline subscriber answered, the operator would flick a switch and connect the two. Aircall and Securicor were simplex. BT was duplex and a forerunner of our present mobile networks.
Now, fast forward to today.
In a pre-CoVid world, Scouts could talk to other Scouts via amateur radio on the third weekend in October each year. Jamboree On The Air is an ad-hoc event that stems from cooperation between local Scouts and radio amateurs. During JOTA, amateur operators set up calls and pass the mic to a Beaver, Cub, Scout or Explorer. Those Scouts pass ’greetings messages’ to other Scouts elsewhere in the UK or worldwide.
Then came CoVid.
Jamboree On The Air this year was held from Friday 16th to Sunday 18th October. At the time, and in most areas, Scouts were at what they refer to as Readiness Level Yellow. Small scale face-to-face activities were allowed, but everyone attending had to be socially distanced. These constraints precluded traditional JOTA operation with the amateur operator sitting beside the Scout. New methods of operation needed to be found.
So, Scouts and their radio amateur partners perhaps needed to take a leaf from the days of phone patch.
Here’s the solution using the likes of Zoom that Borders District Scouts used at the special event station GB2SBS run by John, GM8JBJ and Sue, MM3SLB.
The connection between Zoom and HF is made using an XGGcomms digital interface containing a C-Media CM108 chipset sound card for digital-to-analogue conversion. The interface links the USB socket of a Raspberry Pi running a Zoom session to the HF transceiver 13-pin facilities socket. Normally digital interfaces use a sub-carrier VOX to key the transmitter. An interface was introduced to disable the VOX and add a manual PTT and this box is shown (light grey) in the adjacent picture.
The ’DATA’ position connects the digital interface for digi-modes use and is the pass-through state. The ’PATCH’ position interrupts the VOX and enables the ’TX KEY’. The TX KEY connects Zoom to HF - the ’patch’ state - and keys the transmitter. The interface uses two two-pole on-on switches and a lead and some wiring. On receive, the audio is routed through the interface to the Raspberry Pi audio and on to Zoom.
John, GM8JBJ, was radio operator while Sue, MM3SLB, acted as ‘Zoom’ controller. In fact, GoToMeeting was used (rather than Zoom), but the solution is common to all online meeting platforms. The voice quality of ‘Zoom’ participants was excellent in both directions.
For anyone wanting to set such a system up for JOTA, there are some points to note.
The radio operator must join the Zoom meeting using the PC with the interface. In my case, I used a Raspberry Pi with a camera pointing at the rig so that the young people on Zoom would be able to see the rig and its settings.
Part of JOTA is also generally to work on, and complete, the Communicator Activity Badge when the young people must log 25 stations. Several must therefore be on the Zoom call simultaneously, listening to on-air proceedings for a few hours.
The radio operator must also join the Zoom meeting with a separate PC with headset and mic so that they can talk to the Zoom controller. The Zoom controller can then also hear the on-air proceedings, and hence they know when to tell the young person to go ahead. If this link is missing, the Zoom operator is working blind.
Having three independent on line meeting connections over one broadband circuit does tax the broadband capability, though!
And radio and Zoom operators must of course be in separate rooms to avoid howl round.
Then Scouts join the Zoom call as normal and talk over HF in turn.
Simples! And it worked perfectly.
And the results? 26 QSOs with stations in 18 countries over 10 hours. 10 Scouts participated for about 4 hours each. Another 10 or so stations were heard and logged, including V55JOTA, in Namibia, though conditions faded before contact could be made. Our Scouts passed 15 ’greetings messages’ or patches. And since all had completed a training session beforehand, all will now get their Communicator Activity Badge. The training session was effectively a slimmed down Foundation Course.
The best DX was KA8OFC, Michigan with second place to VY2GF, Prince Edward Island. Best QSO was LX9S, Scouts World Bureau, in Luxembourg.
And the icing on the cake for one of our Scouts was when CR7ARW videoed her greetings message being received and sent us the recording.
JOTA this year was a much-muted affair. Sole operators lamented that they were unable to have any participation with their Scouts. Unfortunately, GB2BS seemed to be the only station who could put Scouts ‘on-air’. We were the only station who thought ahead to use the phone patch concept.
Perhaps more radio amateurs will make connection possible next year.
John Berry, GM8JBJ
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Database collated by Chris G4ZCS
Call sign prefix database
Mid Sussex Amateur Radio Society
Issue 22 - Spring 2020
Please feel free to use and circulate this list. Chris G4ZCS will be pleased to receive corrections and additions as they are noticed. There are over 2000 entries. Additions are continually added, please check for updates. For date and prefix "exceptions" please check with the "Club Log" on-line database, as this is updated daily and is reccomended. Read with care!
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Automatic Position Reporting System (APRS) - Bob G0BUX
APRS - What is it?
- A system for digital tactical data communication
- Introduced in 1992
- Developed by Bob Bruninga, WB4APR
- Uses the AX.25 packet protocol
- Special APRS packets embedded in AX.25 packets
- Operates in un-connected mode
- Mainly on 144 mhz (144.800 in Europe)
Mobile APRS Station - How
- GPS Receiver - with serial output
- Integrated Option
- Kenwood D700/D710 or
- TH-D7A
- The other Option
- Existing Transceiver
- TinyTrak or Open Tracker
Fixed APRS Station - How
- Computer (MAC, Windows, Linux)
- APRS Software
- Maps
- TNC
- Physical (e.g., Kantronics), or
- Software (AGW-PE)
- Transceiver
- Internet Connection
- WX Station (optional)
Extending the Range
- Digipeating
- APRS Internet Servers
- IGATES
- APRS Database and Search Sites
APRS - Why?
- Disseminating WX Info
- Public Service Events
- Tracking mobile stations in emergencies
- Text Messaging
- We’re hams - do we need a reason?
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Intoduction
WebSDR (Software Defined Radio receivers) connected to the internet via a server permit a number of simultaneous connections allowing listeners to independently tune any frequency within the band offered and hear the signals via their own computer audio output (speaker).
These Web SDR's are established and operated by individual amateur radio operators, radio clubs and universities around the world.
Each website offers similar features to operate the WebSDR, firstly an introduction to the sponsor and their installation, followed by a spectrum or waterfall display for the band selected in the various selection boxes.
The type of modulation and filter bandwidth can also be selected to suit the signals you wish to monitor.
The use of HTML5 allows the WebSDR's audio stream to play directly via your compatible browser (Chrome, Edge, Opera and Firefox.) All of these enable full access to any of the WebSDR's in the list below without resorting to the installation of any additional software.
So lets get started - here is a selection of WebSDRs in the UK. You will notice they offer a range of different bands to monitor. The first is Hack Green - Great for monitoring the Sunday morning MSARS 80m club net!
N.B. If there is no audio make sure that you have opened up the WebSDR in one of the browsers above.
iPad Users: Click 'IOS audio start' which you will find on the RH side at top of the waterfall next to HTML5 button.
| Web SDR Name | Location | Bands Covered | Link |
|---|---|---|---|
| Hack Green HF | Nantwich, Cheshire |
160m; 80m; 60m; 40m; 20m; 17m.
|
http://hackgreensdr.org:8901 |
| Hack Green VHF UHF | Nantwich, Cheshire |
70cm 2m 4m + (10m)
|
http://hackgreensdr.org:8902 |
| Southampton Wireless Society | Farnham |
LF 2m 70cm 3cm + Follow the ISS, Funcube-1 and High Altitude Balloon Transmissions on the Satellite Tracking Map
|
http://farnham-sdr.com |
| University of Twente | Enschede, Netherlands |
0-29MHz continuous - Includes WSPR and Chirp Receivers. Full instructions on their site.
|
http://websdr.ewi.utwente.nl:8901
|
| General list of sites | Over 100 SDR's |
For the latest list click:
|
http://websdr.org |
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Built during the late 19th Century, Park Crescent in Brighton consists of 48 Grade II listed Regency houses.
Three of these building were replaced after the Second World War because of bomb damage, and another was the scene of one of Brighton's notorious "Trunk Murders" of the 1930s.
Park Crescent encircles a private garden which was formerly a pleasure ground and cricket pitch; home to the Brighton Cricket Club which later became The Sussex CCC.
Over time many of these houses had been converted into flats, and it was indeed at Flat 3, 17 Park Crescent that I spent my early life growing up.
Flat 3 is in fact on the top floor, with picturesque views of the private garden and beyond, from the lounge and what was my bedroom.
The roof of these buildings is in the form of a double apex style. Imagine an ‘M’ shaped roof where there is a walkable channel in the middle, not only over number 17 Park Crescent but many of the adjoining properties as well - useful I found out later for stringing up a long wire!
In fact this 12 year old child found that by carefully repositioning the hall cupboard and clambering on top of it aided by a pair of steps, I could gain access to the loft via a trap door high up in the wall. A further trap door in the loft gave access to the roof and onto the walkable channel – what a discovery!
My first communications receiver was an ex-government ‘Canadian 52 set’ made by the Canadian Marconi company and sold to me by GWM Radio in Worthing who specialised in ex-government communication equipment.
This covered a frequency range of 1.75-16.0MHz CW and AM.
There were many shops similar to GWM Radio around in the 60’s. The most popular ones were in London’s Lisle Street (Soho) and Tottenham Court Road. The pages of Practical Wireless would be full of adverts from many of these outlets every month.
I was still at school at the time and had saved up my pocket money all year for this receiver. It eventually arrived, packed in a large wooden crate and was waiting for me when I returned home.
The crate had been placed just inside the main entrance hall of the building.
Flat 1, the ground floor flat was occupied by an elderly gentleman and his wife. He couldn’t help noticing when this large consignment arrived, and was inquisitive and enquired what it was.
With great enthusiasm I somehow managed to open the crate, removed the straw and there it was! “A short wave radio receiver” I replied to the gentleman – I may have called him Sir – but then again probably not – especially after what happened over the following weeks.
Having climbed three flights of stairs (managing to avoid tripping over Smokey the cat who belonged to flat two) and undoubtedly stopping for an oxygen break, I and my new acquisition eventually made it to the shack (bedroom).
What was I going to do for an aerial? Now 14years of age, I probably didn’t have much knowledge of amateur radio aerials and anyway I was more interested in general short wave listening.
I recalled how I had previously gained access to the loft, and so that was where my very first radio aerial was to be strung up – attached to the rafters at each end, eventually being threaded though a pin hole in the corner of my bedroom ceiling and down to the radio.
Now at this time TV reception was very poor in the low lying areas of Brighton. VHF 405 line TV only being available from the Rowridge (Isle of Wight) or London transmitters. TV reception in Flat 1 apparently was awful – so the elderly gentleman told me and much worse since that ‘box’ arrived!
“You must be transmitting” he said angrily. Repeatedly telling him it was only a receiver and did not have the ability to transmit fell on deaf ears. I’m afraid, my poor old mum got it in the ear. Anyway he must have sorted out whatever was causing his TV problem as he eventually stopped making any comments.
I enjoyed my first experience listening to the short wave bands very much, and soon wanted more – a better receiver and a decent aerial to go with it.
My interest in the amateur bands began shortly after I started attending Brighton Technical College in Richmond Terrace – just a short distance from home.
I was studying radio and TV servicing and was sent there by my employer Scotts Radio one day a week for five years. Scotts Radio was an independent dealer who had a number of high street shops with their service department in London Road close to Preston Circus – another short walk from home.
They say you remember the best teachers at school; well we had two great ones at college; Ron Bravery G3SKI and Richard Canning G6YJ. Some of you will remember and indeed may have been taught by Richard as he used to also teach the Radio Amateurs Examination courses (RAE).
Richard (known to us as Fred Canning) was a keen CW operator, lived with his wife in Burgess Hill, and for a few years later in his life, taught the RAE at Marle Place Burgess Hill. I can recall his Bungalow in Windmill Drive with long garden and antenna to match.
Richard and Ron had set up an amateur radio station in the basement of Brighton Technical College, and as students we would be given demonstrations of the station.
The station consisted of a KW Viceroy HF Transmitter (100Watts out) and a KW77 receiver. The antenna was a 132ft centre fed Zepp installed between the college and the brewery. All modes were catered for (CW-AM-SSB) although AM was still the most popular (1966 era).
The ‘transceiver’ as we know it today had not arrived on the scene as yet. Separates were the order of the day. Having tuned the receiver into an amateur station’s CQ call, you would then adjust the transmitter to net onto the receiver’s frequency; this by means of very low level RF signal.
Those of us studying radio and TV serving were encouraged to attend the RAE course for a useful form of revision. This would be one evening a week over the academic year.
Now here’s the crack: Richard Canning was such an entertaining lecturer that most of us didn’t just sit the course for one year, but three instead! – Now there’s evening entertainment!
Indeed some of us took the radio amateurs exam in year two for the hell of it, and still came back for more. It wasn’t that we were swats – far from it.
To lighten the evenings lecture especially when the subject matter became dull, Richard would have us rolling about laughing as he re-told stories from the time when he was employed by the Welsh Electricity Board and all the high voltages he had to deal with, and the things that went wrong – although I suspect they had a meaning for us.
There was great rivalry between Richard and Ron with regards to amateur radio stations worked on the air. Indeed both of them wanted to be the first to show off their latest collection of QSL cards.
Working at the Scott’s Radio service department gave me access to a huge number of components – fantastic for the prolific constructor that I was to become. Indeed my service manager Robert Harding was very supportive – after all I could only gain experience which hopefully would benefit the company.
Some of my early home brew can be seen in this picture, including the 4’ long bench at the end of the bed.
Entering the room from behind the curtain is the 600 Ohm feeder of the 132’ end fed Zepp aerial. By the age of eighteen, I had plucked up enough courage (and foolhardiness) not only to climb up onto our roof, but to climb over three other roof tops as well! The antenna I made using 14SWG hard drawn enamelled copper wire. The feeder spacers I made by cutting up lengths of EGA tubing (electrical conduit). The 132’ was fixed at both ends using porcelain insulators with short lengths of supporting wire attached to facia boards.
The Zepp feeder connects to a home brew ATU located on the shelf. Main components within it were the large tapped coil wound around a former constructed using a couple of strips of Paxolin board glued at right angles to each other to form an ‘X’ cross section. The wire was wound over the ends of the X.
Two reasonable wide spaced tuning capacitors were used probably in the value of 150pf – 250pF. The small meter I seem to remember was just used to sniff the RF and was not actually an SWR bridge, although I did construct one at a later stage.
Many of the unusual components were readily available from ex-government radio shops in Brighton such as Arthur Sallis in North Road and Hay & Sons in Trafalgar Street.
The antenna worked like magic proving in one lesson that height (we were three storeys up) was as important as resonant length.
Next to the ATU is the six valve oscilloscope built using a 3” ex-government radar tube. Used mainly for checking on modulation depth of the AM carrier while transmitting.
I seemed to have spent an awful lot of time cutting up aluminium, and I have lost count of how many valve bases I cut out with drills, round and half round files – no fancy valve base cutters at this shack!
Sitting on the bench left, is the first transmitter that I built. It is a 5 band HF 80m-10m 50 watt output AM rig based on the design by F.G Rayer G3OGR in Practical wireless - worked a treat especially with that aerial.
Sitting above it, is a Top Band AM/CW transmitter. Now I have to publically own up here how I practiced a bit of deceit…..
The ‘Codar AT5’ was a popular Top Band (1.8MHz - 2.0MHz) and 80m AM/CW transmitter. This was available to purchase from a shop in Southwick.
I rang them and said I had purchased one of their Codar AT5 transmitters and that it had now developed a fault, and would they kindly send me a circuit diagram so I could fix a repair – something like that.
What kind people – from that circuit diagram, three of us went on to build a copy of that rig. I leave the names of the other two out of this article to save any embarrassment.
On the RH side sitting on the bench is a second hand commercial KW77 all mode receiver – the same model that I saw a year earlier in use in the basement radio shack of the Technical College. SSB was starting to become popular.
Finally sitting on top of the KW77 is a general coverage transistorised receiver – never did work very well (deaf) for some reason so would have been dismantled – the parts used for some other project.
The flat in Park Crescent also saw the construction of Hi-Fi amplifiers – some of you will remember the popular Mullard 5-10 design (5 valve 10 watt output). I constructed two of these on one chassis, built a pair of speaker enclosures, fitted them out with woofers and tweeters – Voilà - Stereo – Herb Alpert – eat your heart out!
While all this was going on in the 60’s the backdrop was ‘Off shore radio ships with the likes of Radio London and Radio Caroline broadcasting pop music usually 24hrs a day from the North sea.
This caught the public’s imagination and was a great hit. Up until then the only station to broadcast pop music was Radio Luxembourg, although that was really only receivable in the evening which tended to fade in and out.
The BBC only broadcast pop a few hours a week on their ‘Light Programme’
August 1967 saw the marine offences bill outlaw the pirates. Shortly after that Radio 1 started broadcasting to fill the hole left by the radio ships. In my opion radio has never been the same since.
Tony G3XQM
