Category Archives: Field Day

CQ WW RTTY Contest

Members of the SNBCG took part in the CQWW RTTY contest over the weekend of 23rd and 24th September.

George M1GEO used his Icom 7100 and solid state amplifier to deliver 400w, using an 80m dipole on the SNBCG tower. The dipole with the aid of an ATU was used on 20, 40 and 80m.

Station two Dave M0TAZ used his Icom 7600 and solid state amplifier to deliver 400w to a ground mounted 1/4 wave for 40m. The 40m vertical is a tried and tested combination, although this year we tried elevated radials after reading an article by Rudy N6LF.

Rudy has completed some extensive testing on ground v elevated radials, you can form your own opinion by reading the article.

Over the course of the weekend, we worked 700 stations in 60 DXCC.

Fred G3SVK also worked 400 stations on CW, and reported some good DX was to be found on 20, 30 and 40m.

 

The weather was kind, allowing us to operate outdoors in our tent. Fred and Dianne provided some excellent food thought the weekend.

A very enjoyable weekend, and nice to see so many members and friend of the club lending a hand.

SNBCG and LEFARS Big Radio Weekend

The August bank holiday provided a great time to play some radio, and join forces with another club for the weekend. Many of team SNBCG are also members LEFARS, and with an active portable group, this was set to be a busy weekend.

I arrived on Friday evening with Peter G0IPA and Dave G7UVW to setup the initial masts, we put up the 144 MHz beam  (9e + mast head LNA).

The 18 MHz 3e beam was recently constructed and required some further testing, although initial results were very promising.

The 7 MHz vertical was constructed from push up poles and 8 radials.

A BBQ was planned for Saturday evening, with Ron G6LTT, Karen and Sharon doing a great job in feeding the masses. Dave M0MBD also provided a very nice Chili con carne with rice. We also had burgers and sausages and some salad, a really nice and very welcome meal. The weather was excellent, with temperatures getting to 27c in the day, and not falling below 18 in the evenings and ideal for camping. The turn out from both clubs was excellent with members travelling from far and wide to partake.

A WSPR transmitter was setup for the weekend using the QRP Labs with a 200mW output into some wire. This provided an indication of the band conditions and was active throughout the weekend.

John M0IDA dropped in on Sunday with his arrow satellite antenna and provided a demonstration on working through satellites.

Altogether a very successful weekend with members operating on 3.5, 7, 10,14, 18, 21, 24,50 and 145 MHz over the weekend, making close on 1,000 QSO in 80 countries.

Further pictures from the weekend are available here.

1/4 wave on 80 meters

The plan was to put up an 18 meter (60 ft) spider beam roach pole and operate a 1/4 wave on 3.7 MHz. We have used both the 12 m and 18 m roach poles from Spiderbeam with the intention of using them to support inverted V antennas and verticals. Previously we used the 12 m on a number of occasions to support a doublet for portable operating, and the 18 m to make a top loaded vertical for 1.9 MHz with an inductor.

On this occasion, we wanted to try a 1/4 wave on 80 m and the 18 m is ideal for that purpose. The pole can be fully extended and then walked up from the ground, but you will often need to use jubilee clips around the poles to stop it collapsing under its own weight. Like the smaller poles the sections do pull out and lock, but in a breeze, the sections can often rock back and forward and then without notice concertina down. Here you can see the roach pole and me for scale.

Using 6 radials and a wire fence the antenna was ready for some testing. The VSWR was 1.1.5, I think with a larger ground plane this may have been lower, but it was acceptable for our purpose.

The antenna was guyed off at 4 and 12 meters, this is essential in even the lightest of winds.

With the addition of a IC-7600 and solid state amplifier, the station was ready to go.

Unfortunately, the bands have been suffering from disturbed conditions due to solar flares, so despite our best efforts, we were unable to work big DX. We did work quite a few European stations, and also a fair few UK and Irish stations.  The reports received from the antenna and the reception performance was very good, and I was able to receive stations from the USA later in the evening. Unfortunately, the USA stations were in a net, so I didn’t disturb them.

The weather also provided some anxiety, over the course of the weekend the wind picked up to a fairly constant 20 MPH breeze. Thankfully despite some groaning the guys held and the antenna came down without incident.

Over the course of the weekend, we worked 80 stations from 22 DXCC.

Easter Field Weekend

During the long Easter weekend members of the SNBCG came together for a radio weekend. Over the course of the four days, two HF stations were set up; one on 7 MHz and the other roaming between 1.8 and 28 MHz depending on propagation.

Dave M0TAZ decided he would try a 1/4 wave vertical on 7 MHz and use his recently purchased push-together fibreglass poles. These poles are often sold at radio rallies in packs of 5 (each pole 1.3 metres) to give an overall height of 6.5 meters. Using two packs of the poles, the required height of 10 metres was achieved.

Chris G8OCV had made some supporting guy rings, these provided anchor points for the guy lines at approximately 4 and 8 meters. The first attempt didn’t quite go to plan, it simply wasn’t possible to walk up the 10m pole, as we found out when we exceed the bend radius of one of the poles. Lesson learned it didn’t make any difference as the fracture was in the joining section that was simply moved to the first section. In the end, we used 9 poles, giving us a total height of 11 meters with a simple wire running down the side for the radiator.

Six 6 radials were cut, each around 10 meters in length, and the antenna was mounted at the base of a wire fence. The earthing system included the 6 radials and the wire fence, and this provided a reasonable match around 1.5:1 at 7.150 MHz. It would have been much easier to use a push-up fishing/roach style pole but experience has taught Dave that these can be tricky to keep up without guying and tapeing over the joints. As we wanted to run linear amplifiers this weekend, the prospect of the pole moving in the wind and/or falling down made, we made up our minds to use push together poles as the first choice. The antenna was fed with coax with a choke unun (or balun) at its base to stop the coax radiating, and this needed to be capable of high power.

The antenna provided reliable service all weekend, and with the addition of 400W yielded over 200 contacts in 40 DXCC countries. An enjoyable part of the weekend was working DX stations later in the evenings, including the USA, Chile, Mozambique, Guinea-Bissau, Israel, UAE, Armenia and Asiatic Russia all on the 40 metre vertical.

DXCC Breakdown on 40 metre vertical

George M1GEO, Fred G3SVK and others operated the other station. George chased some good DX and Fred worked several hundred stations as “GB0SNB” in CW.

Below we see the DXCC breakdown of the second station using the mast doublet on 160 and 80 metres, and the beam (pictured above) on the higher bands. Some of the DX on the doublet and beam included several QSOs into Japan, Fiji, Trinidad, Guinea-Bissau, Cayman Islands and Argentina.

DXCC Breakdown on 160m doublet and HF beam

We also had time for a BBQ and some excellent curries provided by Fred G3SVK. It was nice to see Camb Hams members Geoff G0DDX and Linda G0TPX, and LEFARS members Derek M0XDC, Dave M0MBD and Dave M0VID. RSGB regional man Peter G0DZB also joined us for the afternoon, making the most of the good weather for a ride on his motorbike, and Bill G0IQK popped in on the Sunday afternoon.

Dave M0YOL worked some data modes using his portable setup. All in all, a good weekend was had by all.

SSB AFS Contest

With snow on the ground and the sun in the sky it must be time to do some winter contesting. This weekend members took part in the RSGB affiliated society SSB contest, this takes part on 7 and 3.5 MHz from 2 till 6 PM.

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With a small amount of snow on the ground, and ambient temperatures around +1C we opted for the inside operating position. The station comprised of an Icom 7600, Expert 1.3KFA solid state linear and a doublet antenna at 30m on the bunker tower.

Band conditions on 7 MHz only supported “long skip” with some good signals from Scotland and Ireland, although after a short while even these distances proved difficult. The maximum usable frequency had moved down to 4 MHz, and so a switch to 3.5 MHz was required.

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A look on the Hack Green SDR confirmed 3.5 MHz was very busy, and we soon realised it was hard to find a run frequency. We also noticed a large amount of rasping electrical noise on 3.5 MHz, and so decided to investigate further. At times the signal meter was reading S9 or s9+10dB and so hearing weaker signals was proving impossible.

We changed the mains supply over from fixed to generator, and the noise floor dropped by 3 to 5 S points, interestingly it would seem the noise was coming from the mains, and so this would require some further investigation and most likely a mains filter project for Chris G8OCV.

 

32160162702_84e7a7833e_kThe generator proved to be a little problematic, for some reason it was running a little lean, and so the engine was sounding rather more stressed than usual. This caused the generator to “brown out” a few times as it coughed, wheezed and spluttered in its attempt to generate circa 2KW at 240v.  As they often say if something could go wrong, then it most probably would while your out in the field.

Hopefully the generator will be a simple fix, probably just needing a clean to the carburetor and no doubt another job to be added to the “to do list” before our next event.

 

While we had some fun, drank some tea and generally worked a few people I think its safe to say our score wont be breaking any records. As always we learnt a bit, had fun and generally tried to stay warm.

EME and MS Weekend

Members of the Secret Nuclear Bunker Contest Group (SNBCG) assembled at Kelvendon Hatch to try 144 MHz (Earth Moon Earth) EME and MS (Meteor Scatter) over the weekend of the ARRL EME event As a group we have tried with some success MS QSO and this helped lay the foundation for this weekend’s EME event.

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EME is particularly challenging due to the great distances involved and extreme path loss of the signal after its travelled close on 500,000 miles! The equipment and format of the QSO is similar to MS, we used the WSJT-X 1.7 (currently in Alpha) and  WSJT provided free from Joe Taylor K1JT website.

The weekend of the ARRL EME event was selected as it provided the best chance of working some of the EME “big guns”. Our equipment was quite modest by comparison, but included a

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9 Element LFA antenna designed by Justin G0KSC,

DG8 masthead preamp as designed by Ian GM3SEK with the kit available to order from hupRF.

Linear amp UK  Gemini 2 VHF amplifier delivering 300w.

Low loss LBC600 / LMR600 coax.

Icom 9100.

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We found we could often decode signals, and even the thrill of decoding signals from the K2VEE in EM79 via the moon was incredible…then it happened.

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We answered a CQ call by HB9Q and to our surprise they replied. This was our first and it turned out only EME QSO that weekend.

We continued to have quite a few MS QSO working Italy, Slovenia, Denmark and Norway and also a number of SSB contacts with 30 or so UK stations over the course of the weekend.

It is always nice to try a new mode and to succeed, you must never underestimate how difficult it is to achieve a QSO over that incredible distance. We achieved our goal of making an EME QSO, and regular decoding of signals via the moon. If this has inspired you to have a go I would encourage you to check out  K4MSG guide to small station EME. Also have a look at W5UN monster EME array that has bagged him over 11,000 EME QSO !

QST also published an interesting article “A Basic Approach to Moonbounce” that you may find interesting.

Plans are already being made for the next EME event in November…

RSGB IOTA contest

Members of the SNB Contest Group came together to play some radio in the RSGB IOTA Contest. Some stations make the trek to far flung Islands in exotic parts of the world, we opted for the contest site close to Kelvedon Hatch in Essex.

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The SNB contest site has the added bonus of a 50m onsite mast, making an ideal platform to hang dipoles. George M1GEO and myself decided to operate or respective calls from the two radio setup, using 3.5, 14, 21 and 28 MHz. George also added his 50/70 MHz beam on the mast, and this provided some interesting contacts using MS and JT65.

With the able assistance of Dave G7UVW, Chris G8OCV, Peter G0IAP we soon had the antenna ready.

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Two pump up masts provided the following setup.

Clark 12m: Tri-band Beam A-3S covering 14, 21 and 28 MHz, with a 50/70 MHz beam.

Clark 10m : 15m 4e homebrew monobander.

Bunker: 3.5 MHz dipole at 30m centre

At various times we added some RF power from either the solid state Expert 1.3KFA or the HAL1200_Atlantic amplifier. We had some interaction between the close sited antennas, and at times this dictated the operating modes/times.

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Fred G3SVK provided joined us as our CW operator, Fred can often be found in the lower pasts of the bands chasing big DX.

No sign of the great man this weekend, but, we live in hope.

50 MHz Trophy Cup & International Museums Weekend

The weekend of the 18th and 19th of June saw members of the group assemble to operate as M0SNB for the 50 MHz Trophy Cup and GB0SNB for the International Museums Weekend.

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Over the course of 24 hours for the 50 MHz Trophy, we made a total of 218 QSOs, with our best DX to UZ5U (2320 km). The map shows our contacts.

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Maps and logs from the Museums weekend will be added once the logs arrive from the IWM station manager.

CQWW WPX SSB Contest 2016

Over the 2016 Easter public holiday weekend, the team at the SNBCG decided to participate in the CQWW WPX SSB contest, using the club callsign MX0SNB. On arrival, our usual camp location close to the bunker’s communication mast had become unusable due to recent wet weather, with the grass boggy to say the least! It soon became apparent one of the vehicles was stuck in the mud, and after much pushing and pulling we decided another location would be required. Luckily the owner of the site offered us another location, higher up on the hill with the added advantage “that once onto the hill your vehicle only need to slide down to the bottom of the hill to exit” – a very useful feature!

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Using George M1GEO‘s 14 MHz homebrew beam and Dave M0TAZ‘s 21 MHz beam,  we set up our stations on a lovely sunny Friday afternoon.

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Power was provided by 2 x Honda EU20 generators coupled together and providing 4 kW of peak-power. Enough to run the two stations with amplifiers and a kettle for making tea!

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Dave M0YOL kindly offered his awning, along with copious cups of tea, bacon sandwiches and supplies throughout the event.  We had completed the set up before sun down on Friday, allowing us to complete some testing with both of the solid state amplifiers.George M1GEO and Chris G8OCV had recently purchased an SPE Expert 1.3K-FA amplifier and Dave M0TAZ was using the hal1200_atlantic, with both amplifiers are capable of providing over 1kW of RF power, more than enough to meet the UK full legal power of 400W.

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George M1GEO and Chris G8OCV have designed and built a 3 element 14 MHz beam, the design uses roach poles and provides a lightweight portable beam. The 21 MHz beam Dave M0TAZ constructed was based on DK7ZB design, and the construction details have been previously discussed in this article on his personal website.

The set up inside the caravan (trailer) awning provided a dry and largely windproof operating position, although at this early in the year the evenings are somewhat chilly! The weather provided a real challenge as the weekend progressed. In such a high and exposed location, with storm ‘Katie’ approaching the south of the UK.

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Over the course of the next 48 hours, the rain and the wind increased to storm force with gusts in London of 50 mph, and in our exposed hilltop location gusts in excess of 70 mph were felt rocking the caravan.

This video, comprised to clips from throughout the weekend captures the more sane parts of the experience, with the scary parts unrecorded (because we were all too busy holding things down)!

We lowered the beams and continued as best as possible using a vertical and doublet antenna – well, it started vertical!

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Late on Sunday night and in early hours of Monday morning, the storm really hit had, the awning was in danger of parting from the caravan so the decision was taken to quickly move all the equipment into the safety of the caravan. It wasn’t until the following morning, when the storm had passed, that we were able to assess the damage!

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Unfortunately the beam is not likely to make any further field days, but George M1GEO and Chris G8OCV do have plans for a mark 2 aluminium version soon.

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Dave M0TAZ‘s 21 MHz beam fared a little better with the weather and survived the storm, but unfortunately, the mast will require a new guide rail (a plastic wedge that stops the mast rotating) due to the wind loading put upon the mast in the storm.

Despite the awful weather conditions we did manage to work 744 QSO in 94 DXCC in the main on 14 and 21 MHz.

The following maps show QSO made on 21 MHz (Red pins) and 14 MHz (Yellow pins) showing North America, South America and Asia.

You can view the log and further statistics online using the excellent SH5 contest log analyser software.

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RSGB 21/28 MHz contest

The RSGB contest provided an ideal opportunity to focus activity on the higher HF bands. Previous John M0UKD and I had built beams for  28 MHz 3e beam and  21 MHz 4e beam using the design on DK7ZB website.  28 MHz is a compact design using a 3m boom, and 21 MHz is somewhat bigger at 5m boom.

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The Racal PU12 mast was used for the 28 MHz antenna and Clark 10 for the 21 MHz antenna. Power was provided by the Honda 2KW silent generator and the radio was provided by George M1GEO the Icom 7700 delivering 200w RF.

21317020033_44fe6db48c_zThe operating was alfresco as the October weather was  sunny and warm. The shack table was positioned close to the mast ready for armstrong rotation The Clark mast was modelling some new blue legs, recently fabricated by Brian 2E0FHU. They worked perfectly and once assembled they provided a sturdy base.

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A quick check with the MFJ analyser confirmed the antenna was spot on resonance, and so the CQ calling could commence.

Despite a valiant effort on both 21 and 28 MHz conditions did not support the number of QSO we had hopped, in fact you could say it was a challenge to work anyone at times. QSO could be hard to tease out, and we decided the best method was to work anyone we could  hear. Some big DX did arrive, as we managed to work ZS6AI, ZS5DCF, CX8DS, VP8NO and PS8BR to name a few. The bands did seem to be open, at one stage we listened to a CW beacon in South America that was very loud (apparently 10w).

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Despite the lack of activity or poor band conditions we enjoyed our time operating outdoors in the sunshine.

Both homebrew beams worked well, and this may well be the last time we operate outdoors in 2015.

Further picture from the day are available online.

Thanks to everyone we worked 73 Dave M0TAZ, George M1GEO and John M0UKD

EDIT (30 November 2015)

The RSGB results come through today, and we were pleased to have won the Powditch Trophy for the Leading UK Multi-Op station achieving the highest score on 28MHz. With the help of the team, M0TAZ M0UKD and G3SVK (G8OCV in support).

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