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Old 06 December 2005, 13:01   #11
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Looks a great formula apparently you don't need any power!!!
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Old 06 December 2005, 13:47   #12
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I would have assumed the height of the recieving station was also important?

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Old 06 December 2005, 15:10   #13
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i was in Nieuwport and easily picked up Dover which is about 60+ miles straight line. Aerial is about 4 meters off the sea surface??

I thought 10 miles was max with standard VHf??


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await for comments from Jon Brooks on this.
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Old 06 December 2005, 16:33   #14
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When you're trying to see over the horizon then height at both ends has gotta be relevant. when you're talking to the coastguard remember you're not necessarily talking to the aerial at the named base. One of our local aerials for Liverpool Coastguard is 500ft up on Blackpool tower-which does wonders for its range! Worst place for reception on ch0 from that aerial in our coastguard vehicle is on the promenade right under the tower itself. High pressure weather also has an effect and then we start getting stations we would not normally hear.
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Old 06 December 2005, 18:12   #15
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Quote:
Originally Posted by Simon B
Range = 2.25 x square root of antenna height in metres

This is in ideal conditions though.
Also is this with a unity gain antenna or a 3dB type?

Regards
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Old 06 December 2005, 19:21   #16
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Quote:
Originally Posted by Jon Brooks
Line of sight is taken from the top of your antenna to the top of the other station.
So if you were a coastguard station with an antenna some 200 feet up your range would be preety good.
I called Brixham Coastguard yesterday from the River Dart at Diddisham although only a couple of miles there was a 300' hill between us & we got very good reception both ways.
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Old 06 December 2005, 19:36   #17
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Coastguards usually have several masts to help with coverage of their area - you could have been communicating with an alternate mast away from the coastguard station.
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Old 06 December 2005, 19:43   #18
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Quote:
Originally Posted by roycruse
Coastguards usually have several masts to help with coverage of their area - you could have been communicating with an alternate mast away from the coastguard station.
There must be, but as far as I know the only 'external' mast is on Berryhead at 180', with the same hill in the way
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Old 07 December 2005, 04:59   #19
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Nick,
Brixham CG have got an mast on the top of Dartmouth Collegeas well to cover the dart river.
So where we are ther is Exmouth, Teignmouth, Berry Head, Brixham Harbour, Dartmouth, Prawle, Rame head etc.
When we get called out to an Coastguard incident for example in Totnes, we will be using both Berry head and the Dartmouth Mast. When Brixham receive a call. they look at the Computer screen and see which mast is receiving the highest signal strength and then that is the mast they will use to reply.

A real "blind spot" near to here is Man Sands on the way to Dartmouth. That is within 1.5 miles of the berry head mast yet still because of the headland next to st mary's the signal cannot get through. I have actually acted as a relay on Ch "0" between the rescue teams on the beach and Brixham CG on a couple of occasions whilst out training.

Hope this helps.
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Old 07 December 2005, 06:15   #20
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You might be surprised at what you can hear!

Parents have a boat on the Thames at Reading.

It was often possible to hear Ostend Radio!

So, if you have a handheld VHF in Manchester why not switch it on and see what's out there.

Duncan
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