|
Multi-Tx
DF Sunday August 8th 2021 Organiser Gary M6GLP Location Bourne Park, Ipswich, Suffolk. Click here for road map with zoom. Event Format - full details here. |
 |
 The Ordnance Survey map provided some help on site but Gary's navigational traps were set to offer a serious challenge! |
 |
 |
New
Rxs on the block! Chris's experiments over the last 18 months - blog. |
 George has been designing and building too, see later in report.
|
 And a new DFer too - welcome to Chris B (on the right) |
 Weapons chosen! |
 |
 |
 |
 |
|
Results
|
|
Times (for info - only points mean prizes!)
|
Multi-Star George
|  Ghostbuster Steve
|
|
 With hindsight, a
satellite view and no DF set to encourage us to the wrong side of
barriers, things look much clearer!
|
| So how did our winner find his way
around? Over to George: The day dawned bright and sunny... no, hang on, rewind... for me, this day began a month ago... Though I'm a professional Electronics Engineer, I've never done any receiver design work before, so thought I'd have a go at designing a set, not least because the parts for existing Top-Band DF sets are getting hard to come by. How hard could it be? So I'd cobbled together a few modules, arranged then on a sheet of plastic, and taken them to the Chalkney Woods DF hunt in July for a test on the car-park transmitter before the event. First impression was that strong signal behaviour was very good, followed immediately by the second impression of 'it's bloody deaf'. I decided there and then that I'd improve it, box it, and take it to the next Multi. Much of the deafness turned out to be lack of volume caused by the little speaker I'd bought, and was cured with a rummage in the junk box for an old Marine VHF external speaker. I also experimented with pre-amps, and various forms of sense circuit. |
 |
 |
With no test transmitter, I
had to resort to an RTTY signal on 2.066 MHz (apparently a Naval
Transmitter in the South of France) which comes up every evening after
dark. Not the most predictable way of testing equipment, but hey,
it was the best available. Following a suggestion from Chris, I
went for a 3-pole crystal filter with Micro-processor crystals (3.6864
MHz, 22p each). Worked brilliantly, best value-for-money filter
I've ever had. I think Chris also has a better idea on the
local-oscillator synthesizer chip, much smaller and more convenient
than mine. After much mucking about, and a lot of trouble squeezing a collection of test-modules into two odd shaped boxes that I had lying around, I was left with doubts about the sense, the VCO mode wasn't set up so wasn't connected, no idea if the battery was going to last... at least I thought the gain was good enough. It also looked surprisingly natty, and easy to wave around. So, back to that bright sunny day... well, it promptly clouded over, but the intermittent sunshine during the afternoon gave a very pleasant temperature for charging about in a park. |
| I
began at the start with Roy's set, could hear and take my usual rough
bearings on A, F and K (despite the prior warning that A was very
weak), and much to my surprize, not only could I also hear all three on
my new set, but the sense was working... and it agreed with Roy's!!! My Joker was F (which was also a good signal), so I decided to take a gamble on the new receiver, loaded Roy's set (supposedly) carefully into the rucksack and set off with a frisson of excitement back in the direction of the car park. On moving from the trees out into the open, there was a scene of several DF-ers taking bearings and charging off to the four corners of the park (the joker system is great for that!). Mine was dead ahead, Rx seems to be working, signal increasing, sense still working correctly (or at least consistently, I'll call it working when I find something). After running round the trees for a while, bumping into Richard going the other way (disconcerting, am I going the wrong way?) I finally decided it was in the middle, and dived in at speed. Ducked under a tree, and TWANG... was yanked to a sudden halt by my rucksack, which was now hanging from said tree by the aerial of Roy's receiver which was sticking out of the top of my bag. Carefully loaded his set back into the bag properly this time, and proceeded to F uneventfully. |
 |
| Next
up... G. The receiver sense said G was across the road.
Strange. Sense still giving believable headings to A,K and F, and
it worked all the way in to F. Ok, map says there is a patch of
woodland over there... let's go. The place looked deserted, but
the signal was strong, and rounding the corner, there was Richard...
who promptly ran past me going the other way again. Hmmm.
Still, the signal is good this way, and the path leads deep into a dark
tree-lined hole, perfect hiding place. And indeed, after
scrambling across some tree trunks and wading through some undergrowth
I found it. Next up was H, and by the time I got there, both
Richard and Steve were tramping back and forth around a large
bush. I briefly confused myself, moved off in another direction,
came back, and decided it was a couple of feet into the bush they were
peering into. I ran round the other side hoping for another way
in, and heard an exclamation of "THERE IT IS!" from the other two. Where to next? A and K had both been weak from the car-park end of the park, so I marched straight back into the middle of the park to find K a reasonable signal, and A still weak. K was to the north, so off I went. Straight into the woods on the north side of the park, and the little receiver excelled itself by leading me directly to the wire. It's hard to miss a piece of aerial wire when it's touching the nose of the receiver. Triffid nearby, and I'd beaten Richard to that one. Heading for L, I managed to confuse myself, or rather I was confused by Gary who'd hidden M closer to K than L was. I wasn't expecting that! and as I was hopping channels trying to catch the ghost (which I only heard once, weakly) I got a short part of a transmission that wasn't 'L' in morse, but was a good signal. Steve and Richard were close by, and after what seemed like ages waiting for L to transmit again, Steve moved off, followed by Richard. Eventually L transmitted again, and I headed off to find the two 'old hands' emerging from a bush in the distance. If only I'd worked out what transmission was on... I can see from the timings now that Steve found M while I was looking the other way. I could have been second or third to that one, rather than forth. As it happened, I didn't take enough notice of where they emerged, and it took far too long to find the Triffid after arriving at the tree with L's transmitter in it. Bearing to M was back the way I'd come, so back to the scene of my earlier confusion to find M properly this time. |
|
| A
long way to A... I'm sure everyone had a similar experience with that
one... where on earth are the bearings taking me? out of the
park, down the road, into the marsh (slight exaggeration) then I
performed an embarrassing amount of tramping up and down to find A. I
took comfort from the fact that the grass looked well trampled, so I
obviously wasn't the only one to struggle there. With a sigh of
relief, B was a good signal, back towards the marina, so I set off,
remembering that the adjacent A137 is where the clutch pedal on my car
broke a couple of months ago leaving me without transport to get to the
one of the earlier DF hunts. Still listening for the Ghost while back-tracking to B... nothing heard, must have stopped by now. That's one aspect of the hunt I haven't come close to managing yet. Did pick up a couple of bearings to C while listening on that channel though, so flicking the switch certainly wasn't wasted. |
| The receiver excelled itself again at B, found the Tx wire when the nose of my Rx touched it. Doesn't get much better than that. Spotting the Triffid was another matter entirely. Took another bearing to C, good idea now where it was, but time for a lonely break and a drink of water. |
| I
hadn't seen another DF-er since M, and was wondering what I was doing
wrong. However, just at that moment, as I was setting off for the
run in to C, a head appeared out of the long grass, and a shout.
It was Vaughn. Had I found C's Triffid yet? ...erm,
nope. Haven't found Tx C yet, but it's a little way behind
you. To which he explained that he knew that, but was a tad
frustrated at not being able to find the associated Triffid. For
some considerable time it didn't look like I'd be any use either, but
eventually we stumbled across it down in the grass.That was the last of
my 9 transmitters, as the Ghost was long-gone by now. There then followed a pleasant stroll back through the park discussing receivers with Vaughn, and generally hanging out as he went for L and M. I left him to as I had to return to F to validate, finding Chris B in the bushes looking for it too. Seriously impressed with his first attempt at a DF hunt. Final thoughts on the new receiver... I love it. It's a little lacking in sensitivity (I'll have to fix that) and it picks up a little spurious carrier on 1960 from it's own PIC micro (too many wires from the top to bottom boxes, I'll have to re-arrange the internals to sort that), but I think it deserves the trophy. Big thank you to Gary for hiding the transmitters (and perhaps a couple of the triffids were hidden a little too well!), and Roy as always for the equipment (and everyone else required behind the scenes to make Multi-DF happen that I haven't noticed yet!) See you all next time, George G0JWQ. |  Well done George - a fitting Olympic 2020 version of the Multi-Star! |
|
Hero/Handicap point changes this event 
 Other significant HPs held by those not present at this event are are Colin F 130 and Philip C 119 Careless discarding - Silly 'boys' Roy E and Tim P have put themselves out of range of Colin F on 130. Only Philip and Gary are in a position to depose him! Level changes - we have ways of stopping you winning ! See Jokers George F moves from level 2 to 3 (green or yellow jokers from now on and cannot discard to below 20 HPs). Chris B, having completed his first event very successfully moves from level 1 to 2 - will have a green joker (A F or K on his next event). For reference - once you have won two events you move to level 4 - any joker and cannot discard below 40 HPs |
|
Next Event Discussions after the event indicated that many are unavailable for September 5th, so our next event is on October 3rd with Tim in charge. Watch this page for details |