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Plessey Watchman primary radar

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Plessey Watchman primary radar

Old 29th Nov 2018, 21:25
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Originally Posted by Mooncrest View Post
when the 424 eventually pegs it ?
You mean, it hasn't?

Anyway, AIUI, w.e.f. 2020 EASA won't be permitting radar vectoring in Class G airspace. All the jets will be getting in using SkyDemon on an iPhone...if they're not already...
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Old 29th Nov 2018, 22:38
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Dear Lord.........
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Old 30th Nov 2018, 01:46
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Originally Posted by HEATHROW DIRECTOR View Post
Dear Lord.........
You called?
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Old 30th Nov 2018, 19:04
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Originally Posted by chevvron View Post
I believe there was a 10 cm Plessey AR15 at Luton which wouldn't interface with other LATCC radars so it was just switched off and left there.
There was, god bless its valves. I held the first UK validation on an AR15 in 1974. The antenna was on a small tower but we were already over 500ft up so the antenna was angled half a degree down. Fantastic low level coverage. Great radar. We were the second airfield in the country, after Heathrow, to get SSR.
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Old 28th Dec 2018, 10:04
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Originally Posted by vintage ATCO View Post
There was, god bless its valves. I held the first UK validation on an AR15 in 1974. The antenna was on a small tower but we were already over 500ft up so the antenna was angled half a degree down. Fantastic low level coverage. Great radar. We were the second airfield in the country, after Heathrow, to get SSR.
Plessey installed an 'AR1b' head on Farnborough's tall concrete radar tower after the '74 airshow. This which I believe was the prototype AR15 was no good as it was too high agl and ground reflections tended to bounce up and cancel out high cover above 20,000ft; as we did area radar at the time (including autonomous airway crossings), good high cover was essential and the Marconi S232 wasn't approved for area radar use so we got our AR1 back and were never included in the AR15 replacement programme.
The AR1 soldiered on until it was replaced by a Watchman in 1991 (when they had adjusted the tilt of the aerial sufficiently) on the same tower, but when TAG took over the airfield, this radar tower was on Qinetiq property so the radar was replaced by a (in my opinion) somewhat inferior Raytheon ASR10 wef 23 Nov 2002 when we made the move to the new control tower.
The RAF recovered their Watchman for use as a spare but all the radar consoles were left in situ in the old control tower (the RAF having switched to raster scan consoles and thus having no use for them) and they were demolished with the old control tower in early 2003; what a waste; surely they could have been sold elsewhere even if only for spare parts use.
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Old 28th Dec 2018, 11:19
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Wasteful indeed, chevron. Like when NATS started replacing the Astrolite headsets with the Jetlite about twenty years ago. No technical advantage as both headsets used identical components. I wonder how many perfectly serviceable and almost new (and expensive) Astrolites ended up in a skip ??

I hope there is space in a museum, or outside one, for a Watchman and S511 head, when the last one finally stops turning.
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Old 31st Dec 2018, 14:03
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Originally Posted by vintage ATCO View Post
There was, god bless its valves. I held the first UK validation on an AR15 in 1974. The antenna was on a small tower but we were already over 500ft up so the antenna was angled half a degree down. Fantastic low level coverage. Great radar. We were the second airfield in the country, after Heathrow, to get SSR.
I'm no radar tech. If I'm reading this correctly, the antenna would usually be installed completely level. I'm surprised a half-degree tilt can make such a difference. Are there any downsides, such as uneven wear on the turning gear or degraded coverage elsewhere ?
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Old 31st Dec 2018, 14:39
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Originally Posted by Mooncrest View Post
I'm no radar tech. If I'm reading this correctly, the antenna would usually be installed completely level. I'm surprised a half-degree tilt can make such a difference. Are there any downsides, such as uneven wear on the turning gear or degraded coverage elsewhere ?
We had to have a special mounting plate installed for the Watchman at Farnborough; actually 2 were made because the first one had the tilt wrong!
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Old 31st Dec 2018, 20:36
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Mooncrest: As an ex-radar calibrator I can confirm that surveillance radars are installed and commissioned with various Ae tilt angles to optimise their performance for specific sites and/or roles depending on the unit's Operational Requirement. Agreed, most Watchmans were commissioned with 0 degree tilt but many were +/- 1/2 degree up to 2 degrees either way.
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Old 1st Jan 2019, 05:12
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Thankyou Downwind. I learn so much on this site.
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Old 1st Jan 2019, 11:45
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I think it was determind on the height of the tower on which the radar was mounted; ours was quite high compared to other airfields.
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Old 2nd Jan 2019, 11:10
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Leeds Bradford is higher still, at about 680 feet. If and when the LBA Watchman is replaced, I wonder if this will have to be accounted for. Perhaps the new Raytheon and Thales machines can overcome aerodrome elevation issues in other ways.
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Old 2nd Jan 2019, 15:15
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Originally Posted by Mooncrest View Post
Leeds Bradford is higher still, at about 680 feet. If and when the LBA Watchman is replaced, I wonder if this will have to be accounted for. Perhaps the new Raytheon and Thales machines can overcome aerodrome elevation issues in other ways.
I understand what you''re saying but I'm talking about height above airfield level, not amsl.
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Old 2nd Jan 2019, 16:26
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Originally Posted by chevvron View Post
I understand what you''re saying but I'm talking about height above airfield level, not amsl.
My mistake.
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Old 3rd Jan 2019, 01:57
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Used to have a 'Watchman' at HMS Cambridge, Plymouth - for range safety. I think it was also monitored by London Mil.
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Old 3rd Jan 2019, 11:14
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The Watchman must be a good machine to have such longevity. The one at LBA is approaching its 30th anniversary and has had the necessary modifications to guard against 4G interference. I wonder if there would be more of them still operational if this mod hadn't been necessary ?
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Old 3rd Jan 2019, 15:42
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Originally Posted by ex_matelot View Post
Used to have a 'Watchman' at HMS Cambridge, Plymouth - for range safety. I think it was also monitored by London Mil.
'Plymouth Mil' radar still operates I believe using radar heads at Plymouth and Portland to provide LARS and DACS; don't know whether they're still Watchman or its successor though.
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Old 4th Jan 2019, 16:15
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Originally Posted by chevvron View Post
'Plymouth Mil' radar still operates I believe using radar heads at Plymouth and Portland to provide LARS and DACS; don't know whether they're still Watchman or its successor though.
Still Watchman, and will be for the foreseeable since they're not being replaced by Thales STAR PSRs under Project Marshall.
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Old 6th Jan 2019, 20:37
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I'm out of place posting here but fascinated to read your memories nonetheless.
Very sad to read the names of once great British companies - Marconi, Plessey, Cossor, Decca - that no longer exist.
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Old 30th Aug 2019, 14:57
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I was leading the Watchman engineering team at Cowes when we went through the the processes of selling it to NATS. We offered our standard tower, that was in service around the world, exceeded all the requirements and looked the part. NATS rejected it and insisted on the 'scaffolding look alike' version. We hated it but the customer is always right etc etc.
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