Tag: secret nuclear bunker

MX0SNB takes part in the CQ WW WPX Contest

The Easter bank holiday weekend and the WPX contest provided an ideal first field day in 2016.  The event was located at Kelvedon Hatch SNB near Ongar in Essex and used the club call MX0SNB. On arrival at our contest site close to the mast the recent wet weather had made 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,

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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.

Using George M1GEO 14 MHz homebrew beam and my 21 MHz beam  we setup our stations on a lovely sunny Friday afternoon. Power was provided by 2 x Honda EU20 generators coupled together and providing 4 Kw of power. 26111379835_31761daa16_k

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Dave M0YOL kindly offered his awning and copious cups of tea, bacon sandwiches through the event.  We had completed the setup before sun down on Friday, allowing us to complete some testing with both of the solid state amplifiers. George had recently purchased a Expert 1.3K FA amplifier and I have been using the hal1200_atlantic for the last few months.

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 light portable beam. The 21 MHz beam I constructed was based on DK7ZB design, and the construction details have been previously discussed in this article.

Audio clip working India AT5R

The setup inside the awning provided a dry and mostly 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, with a high exposed location  and storm Katie approaching the south of the UK. katieOver the course of the next 48 Hrs the rain and the wind increased to storm force with gusts in London of 50 MPH and in our exposed hilltop location more like 70 MPH. We lowered the beams and continued as best as possible using a vertical and doublet antenna. Late on Sunday night, early hours of Monday morning the storm really hit, 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.

The wind caused some damage to George and Chris beam, this now requires some TLC.

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Unfortunately the beam is not likely to make any further contests, but team GEO do have plans for a aluminium version soon.

My 21 MHz beam fared a little better with the weather and survived the storm, 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.

caribbean CQWPXEU CQWPXUSA

73 Dave M0TAZ

Operating GB0SNB special event call from the Kelvedon Hatch SNB

On Saturday I operated from the Kelvedon Hatch Secret Nuclear Bunker near Ongar. The bunker is a large 3 level underground site, with a 50 meter mast on the roof. The bunker was active until 1994.

The bunker has a permanent special call sign GB0SNB and is open to the public as a museum.

Working with George M1GEO we completed some QSO on 5 MHz, 14 MHz and some VHF contact on 145 MHz.

You can read more about the bunker online, and if you’re local why not plan a visit. The current owner Mike Parish gives you a virtual video tour below.

The Icom 7100 provided HF and VHF. To the left is the TYT MD380 and right Icom E92

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Operating is completed from the original home office radio room, although this equipment is on the back wall its only for show.

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Here you can see George M1GEO tinkering with the IP and the co-located GB7KH DSTAR repeater.

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New antenna testing at GB0SNB

Exposed on the side of a 50 meter mast the antenna often requires maintenance. George M1GEO and Chris G8OCV have over the years perfected the best way to mount the antenna, and on this occasion is had lasted close on 2 years. Antenna maintenance in the afternoon sun is much preferable to winter rain, so we too advantage of the weather to pull up the new doublet antenna.

 

The doublet is 40m per leg, into 300 Ohm ladder line and then a 4:1 Balun.

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The centre of the antenna is made from a plastic chopping board from one of the discount value stores, ideal for insulators. The wire is multi strand 13A flex, ideal for antennas and hopefully robust enough to survive the winter weather.

The centre of the antenna is pulled up onto the mast, elevated to 20m and the ends are on one side into a tree and the other a warning siren.

Dave M0TAZ (Left) and Chris G8OCV working 80m SSB

 

 

Its quite difficult to locate suitable points for the antenna ends, and elevation without snagging in the local trees is always a challenge. Once setup we managed a couple of QSO on 80m.

73 Dave M0TAZ

© 2015 Dave, M0TAZ