Andy M6GND has summed up this communications exercise very well. I will however add some detail to explain my reason for going to Dartmoor on this particular occasion and the local conditions.
I have made many backpacking trips exploring Dartmoor, some of these with the added weight of a Clansman RT351 or RT320. Although there are relatively few large trees on the high moors from which to suspend aerials. The area does benefit from low ground impedance and very low man made noise, plus tranquillity and outstanding natural beauty.
Some years ago a friend moved from Hadlow in East Sussex to Drewsteignton As a professional electronics engineer who also hired out Public Address equipment, he was the obvious choice to provide suitable PA kit for the village fair. The Teignton Fair not only has music, but often this is provided by some very good bands and performers
Little persuasion was needed for several friends and I to make an annual pilgrimage to the Teignton Fair, with at least the excuse of helping assemble the PA equipment and lighting kit. Perhaps the outstanding Real Ales available, such as Jail Ale, from the Dartmoor Brewery (previously Princetown brewery) were a slight motivator! However what the village fair commitee did not initially realise, is that the PA kit was a true professional set up with three kilowatt sound rig and huge bin speakers that “The Who” would have been proud of!
Usually we would camp on the high moors for a couple of nights with perhaps one night in the bunkhouse at the Drewe Arms. For this years trip we decided to take the easy option and have just one night camping on the North Moor. This entailed parking near the Warren House Inn, one of the highest pubs in southern england, then walking about 1km onto the north moor to camp. We would then proceed to Teignton the next morning in plenty of time for the fair. There was an obvious advantage here, as we were within fairly easy reach of the Warren House for evening refreshments and the world famous Rabbit Pie.
After a relatively restrained evenings sampling of the local ales, finally at around 2230 we made our way back to camp over several long abandoned mine workings streams and boggs. Having erected out tents earlier we shared out a bottle of Cabinet Sauvignon and bedded down for the night. We were all awoken by a servere thunderstorm in the early hours of the morning, accompanied by very heavy rain.
As we were already at around 1300 feet thunderstorms take on a new perspective. With the velocity of sound being about 1126 feet per second (at 20 degrees C) this makes the time between lightening and thunder clap about 4.7 seconds, I estimated that we were within half a mile of the storm, which is very close! Corona discharges could be heard singing in the small tree nearby and metallic hoops above of my colleagues tent! This electrical activity was to affect HF communications for most of the next day.
We had to wait until rather late Saturday morning for the rain to stop long enough for our tents to be packed away in relative comfort. When we eventually arrived at Drewsteignton most of the PA gear had already been installed, this just left the lighting rig consisting of eight Par Can 1 kW enclosures. There had however been some developments with deployment of the lighting as the new proprietors of the Drewe Arms had decided that everything had to be run from just one 13A mains socket. Previously we have used the three phase supply and decided not to try and explain that it is difficult to draw a peak demand of over 32 Amps from the single 13A plug!
With abandonment of the main lighting some simple LED displays were kindly loaned by a local disc jockey. With most of the work already done it now seemed a good time to carry out quality control checks on the Otter Ale. Whilst speaking to some of the locals they told us that there had been a direct lightening strike on the church tower, which was fortunately protected with several stout lightening conductors. The small telephone exchange having sustained damage to various items of line equipment.
The time was now approaching 1645 and the 1700 schedule that I have made with Andy M6GND on 80m AM. I grabbed my Clansman RT320 from the bunk house and accompanied by prospective SARS member Richard proceeded around the back of the Drewe Arms and nearby church graveyard. We quickly deployed 18.5 metres of the military Kevlar reinforced wire cunningly suspended between a small Apple tree and Oak sapling at no more than 2 metres above the ground.
I put out a call on 3.615MHz using AM and was answered by Mervin GW8TBG in Wales using a Collins TCS12 and AR88 receiver. Mervin was putting out a good signal and we spoke for about ten minutes, however the conditions were not wonderful and my signals were eventually lost in the noise. I heard nothing from Andy M6GND on 3.615 and according to our previously arranged schedule, called on 7.143 at 1715. I was rewarded by a weak but good readable signal from Andy. We were both experiencing strong interference from SSB stations and decided to move frequency downwards by 3kHz to 7.140MHz. This was clear enough to pass reports and hold a further brief exchange but the static crashes left over from the previous nights thunderstorm made communications difficult.
Whilst establishing relatively local communications on 20 metres was probably unlikely, we tried 14.286 for a schedule at 1730 but again this was already occupied by a very strong Italian station and no further contact was made. Keeping to our theme of performing practical communications exercises using old military equipment. The above does prove that even under unfavourable conditions it is possible to establish effective contact using low power and inefficient aerials.
The Clansman PRC320 (RT320) has an output power of only about 7.5 Watts (30W pep) on AM and on 40 metres the length of aerial I was using was not adjusted from that employed on 80m. Andy was restricted to 10W and had to be content with using the low power (6W pep) setting on the RT320. Considering that the wire I used was only a couple of metres above the ground, the equipment performed very well. Obviously we could have used SSB which would have considerably reduced the noise bandwidth but that would have been too easy!
Despite one shower of rain the rest of the evening went well with the two support bands performing on the mobile stage. There was a Hog roast and lots of entertaining stalls and sideshow games, all with the purpose of raising funds for local charities. The evening culminated with local band the Moob who delighted the crowd with their very tight and professional performance.
My use of radio on this occasion was fairly brief but follows an intention to combine radio with other events and outdoor activities. This is very much the ethos by which we endeavour to run the activities at Beach Head Radio Site. Hopefully combining our time in the fresh air with some practical or theoretical radio.
Anything from comparing the relative efficiency of aerials, checking practical radiation patterns using high-grade test equipment or simple transceivers, How to set up a military transceiver under field conditions or correctly fit an “N Type” or BNC plug without getting any solder on the outside of the centre pin. And no, you do not feed the solder through the inspection hole in the pin!
We open the Beachy Head Radio Site regularly, especially Wednesday afternoons and Saturdays. And are planning a lot of activities throughout the summer, with Bacon and Sausage rolls normally available around lunchtime for all friends and visitors from the club. Just contact Barry, Andy or Steve if you are interested and we will make sure that there are plenty of food and refreshments available.
When not actually engaged in communications on other channels, we normally monitor the following frequencies:-
3.615 MHz (80 Metres AM Calling and working VMARS etc)
51.60 MHz (6 Metre All Modes section of band. Our primary calling and working channel. Clansman and other ex military )
70.40 MHz (4 Metres FM)
145.50 MHz ( 2 Metres S21 FM Calling) or 144.300 MHz (SSB Calling)
We await your calls.