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Chelmsford Amateur Radio Society

CARS Meetings: Jan-March 2014

Award for All

January Meeting
Tuesday, 7th January 2014
Oaklands Museum, Moulsham Street, CM2 9AQ
"Building a Successful Remotely Operated Station"
John Regnault, G4SWX

Technology is always moving forwards and Remote Operation of an Amateur Radio Station can now be within the reach of most people. Indeed for some it may be their best option, as they get older or live in a flat or noisy domestic environment. However things are not always as easy as they might first appear and remote operation can introduce many new issues and problems (not least of which is getting a reliable internet connection!).

John G4SWX being introduced.

John Regnault G4SWX is RSGB VHF manager but has also had two years extensive experience of remote station operation including operating 144MHz EME as well as HF. His talk included slides that covered the licence clauses that enable remote operation and the requirements for failsafe and adequately secure links (so Microsoft was not on his recommended list, unless you fancied driving miles to hit CTRL-ALT-DEL!).

PC Remote Control of a TS2000

Instead, he showed that modern generation hardware such as dedicated RRC1258 interfaces from are an example of a better approach. These can transform RS232 PTT, mic, audio etc. to be carried with low latency over Ethernet, potentially without needing a computer at all. This can be complemented by Ethernet controllable relays etc. for antenna or PA switching (Swedish webswitch products from were one of John's favourites)

RemoteRig Interfaces

John also showed how existing hardware such as rotators could be adapted to Ethernet control courtesy of products from as well as tips such as having a webcam pointed at SWR meters or temperature gauges in the remote shack for monitoring. Attention to detail had resulted in a MTBF of 3months+.

An impressive set of live demonstrations included remote operation of a TS2000 and an Elecraft K3. The latter used an Elecraft K3/0 as the remote head. This model has no internal rf but provides the perfect radio-like user interface (as opposed to the more common radio-console software on a PC). Just a fraction of a second latency could be heard - quite impressive. Digital modes such as JT65 also worked well through the remote link.

Elecraft K3/0 Remote Unit

Allowing for two way audio etc, John indicated that link speeds of ~200kb/s were needed - not too demanding. His own though had an added feature, as there was no ADSL to his remote shack. Instead Ubiquiti Wi-Fi links had been adapted to give 6Mb/s 802.11b over a 10km range in the amateur part of the 13cm band!

The talk had attracted a substantial audience including visitors from Cambridge and even Ireland. Many thanks to John for travelling from Suffolk.

February Meeting
Tuesday, 4th February 2014
At Oaklands Museum, Moulsham Street, CM2 9AQ.
“A Hundred Years of Amateur Aerials”
Presented by Tony Gilbey, G4YTG

Chairman John, G1UZD opened the meeting reported that the RNLI Event at the Marconi Sailing Club was a great success and thanked everyone for their assistance who were involved.

The Skills Evening was also a great success thanks to the effort put in by Peter Sipple, M0PSX (who was lecturing elsewhere this evening).

Peter Watkins received a round of applause for appearing on the TV with Michael Portillo and getting him to send "Marconi" in Morse.

He then enquired whether anybody had worked anything interesting on the Bands - he said he had worked Butan and an island in the South Indian Sea.

In introducing the 100 Years of Amateur Radio Aerial Slides he reminded the audience to think back to a hundred years ago when the original amateurs were not so fortunate.   Based on archive material, this fascinating talk will present aerials from across the years!

Material courtesy of Elaine Richards, G4LFM (RadCom Editor) who manages the RSGB archives, with an original presentational spin by our very own aerial guru, Tony G4YTG.

Chairman John Yates, G1UZD opening the Meeting
Photo by John G8DET

One of the many slides showing Radio Amateurs and their Aerials over the past 100 years

Many of the Aerial were upwards of 75 feet high and at least 60 feet long - the sort of Aerial which would cause a modern Council Planning Officer to have a fit!   In those days they really believed in large aerials.
A point reinforced by Tony, G4YTG as he read the script.

Another slide with Trevor, M5AKA watching on the right

Tony described in simple terms how an Aerial could be made to tune more than one Band with the addittion of "Tuned Stubs" or "Tuned Circuits".   By clever selection of tuned frequency circuits one could arrange for the Aerial to behave like two separate Aerials without any mechanical means.

Tony showing how a closed 1/4 Wave Stub acts as an Open Circuit at one frequency while if Open Circuit at the same frequency appears a Short Circuit.
On the right Tony is holding part of the late G3GNQs TriBander Aerial - the bulges being the Coils.

Geoff Mills, G3EDM then described the two band Aerial which was designed by his late
Brother and built by Fred Leach, G2HNF, Tony and Geoff.

The clever point was that the Inductance is constructed by a long length of rod inside a joint in the beam each side of the fixing point.   This provides and lower wind resistance and provides a high "Q" - the proof it has been in use since 1987 without any maintenance and is used in daily contact with Australia.

Tony then produced a 1/2 Wave Dipole on 2Metres - he said this has been on his previous 4 cars - tunes 2Metres and because it has a 1/4 Wave Open Circuit Matching Stub mounted above the half way up point - looks like a 1/2 Wave Dipole on 70cm.
Tony also said that it could be looked like another 1/4 Wave Aerial mounted above the lower one, thus increasing its effective gain.

Initially this was made out of bicycle spokes and as such submitted to the RSGB RadCom as a High Gain Magnetic Mounted Aerial - after a tremendous wait they returned the script and sugested he submit it to Cycling Weekly!

Tony showing how an Open 1/4 Wave Stub acts as an Short Circuit at 70cms.
Photo taken by Colin, G0TRM on his new Mobile Phone

Murray, G6JYB supplied the computer with Colin, G0TRM operating it.

David, G3SVI and his Wife Myra provided the large audence with lovely cups of tea, coffee or chocolate and biscuits during the Break Period.

The Raffle was organized by James, 2E1GUA and Carl, G3PEM with lots of great items.

Another good evening in our nice new venue of Oaklands Museum - thanks to the Museum Staff who look after us by putting out chairs and tables etc.

March Meeting
Tuesday, 4th March 2014
Oaklands Museum, Moulsham Street, CM2 9AQ
“Digital TV, Radio and Amateurs - What is Next”
By Murray Niman, G6JYB

In his latest update (don't forget Murray produced his first presentation on Digital TV and Radio in 2002!) on new developments Murray G6JYB explains the new technologies and next digital technologies that are arriving in our lounges and shacks.

Murray was pleased to see such a capacity audience with the standard 60 chairs plus 24 additionals plus standing at the back - shows how popular Murray's presentations are.

Topics Murray presented
Photo by John G8DET

The preparation for the next Digital Switchover (700MHz Clearance) is quietly underway (for both Freeview and DAB) as frequency space is needed for more changes such as 5G-Mobile.

Slides shown - Only purchase a TV with Freeview HD (DVB-T2) to be future proof

Digital Radio Switchover is also in prospect

Murray then went on to enlighten the audience about what "they" have decided or not - depending on the detail - regarding FM and DAB radio.   Fortunately for FM HiFi lovers the Government have delayed the projected "Switch-off of FM radio" until after 2015.

In parallel, leading Radio Amateurs are also adopting new technologies for Digital Voice, Data and TV, some of which have real potential to be ‘killer-apps’ and show the hobby in a modern light (like digital colour TV in 2m/70cms).

You first heard at CARS that ‘no-Freeview-HD tuner=no future’.
Now hear the next instalment and be the wiser before you go shopping!

At 8.45 there was a refreshment and social break.

Myra and David assisted by James serving a nice cup of tea or coffee to Denis Phillips, G8AAE with Murray waiting for his turn.

CARS Chairman, John holding the Raffle basket for Murray to draw the winning ticket.

During question time someone asked what Ofcom were proposing to do about the 35 million cars on the road - most without DAB.
Murray said that all new cars were provided with a DAB set and they had got a lot better - shouts from the audience "I have just purchased a £30,000 Audi-A6 car and it does not have one!"

Murray said that he drives often from Bristol to Chelmsford and the DAB coverage is now better than FM.

Another quest was "Who are they who make these decisions?"
Answer Ofcom but often dictated by the EU.   Note the days of having the blind Radio Amateur, Angus McKensy's public Listener Panel seem not long gone - big brother and commercial interests seem to dominate.

Thank you Murray for delivering yet another tremendous presentation - Hands up all those with out-of-date TVs?

Murrays Slides: CARS Digital Talk - 2014

CARS famous Raffle was run by President Carl, G3PEM and James, 2E1GUA.

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