Decca 424 Airfield Radar
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Originally Posted by Gordon Dennison
The 424 was not the first aerodrame radar at LBA. It was preceded by one that I cannot unfortunately remember the name of. It was a very imprecise piece of equipment, but was used for talk-downs. In those days, Air Traffic Control was located in a sort of diy glasshouse on top of the old ex-RAF Officers Mess. The radar was mounted on the roof with a sort of periscope suspended from the ceiling in the centre of the visual control room. Luckily, I did not need to validate on the equipment as it was withdrawn by CAA.
Originally Posted by link about the ARAA
The airports known to have installed ARAA are: Southend, Swansea, Leeds/Bradford, and Elstree.
A great film ! Just for a moment I thought the commentator was Harold Wilson, doing a spot of moonlighting from his 1963 Labour Party Conference speech about the white heat of technology etc. 
Thread Starter
Hello Gordon. Good to hear from an ex LBA Managing Director. I seem to recall reading about your ATC heritage in one of my books and your personal recollections on this site make interesting reading.
I only recently found out about the 424 when I saw it behind a BKS748 in an old LBA pic. Considering I thought the ACR430 was LBA's first radar I was equally surprised to find that the 424 was itself preceded by the EKCO ARAA. Your description of it mounted on the old rudimentary control tower sounds about right. I think you can make it out on some of the old black and white pictures from that era. Unfortunately I don't have the means to put them on here.
Do you remember roughly when the 424 was superseded by the 430 ? I'm now aged 41 and can remember back to around 1973 and the sight of the 430 whirling round in "talkdown" mode is fixed firmly in my mind !
Nice to see plenty of (mainly) fond recollections of old radar equipment from everybody, not just the Decca and Plessey machines but Marconi as well.
And those Corgi models of the 424 are the last word in cool. I must keep an eye on ebay.
I only recently found out about the 424 when I saw it behind a BKS748 in an old LBA pic. Considering I thought the ACR430 was LBA's first radar I was equally surprised to find that the 424 was itself preceded by the EKCO ARAA. Your description of it mounted on the old rudimentary control tower sounds about right. I think you can make it out on some of the old black and white pictures from that era. Unfortunately I don't have the means to put them on here.
Do you remember roughly when the 424 was superseded by the 430 ? I'm now aged 41 and can remember back to around 1973 and the sight of the 430 whirling round in "talkdown" mode is fixed firmly in my mind !
Nice to see plenty of (mainly) fond recollections of old radar equipment from everybody, not just the Decca and Plessey machines but Marconi as well.
And those Corgi models of the 424 are the last word in cool. I must keep an eye on ebay.
Last edited by Mooncrest; 4th May 2021 at 10:41.
I may be wrong but I don't think the 430 was made until after 1973. I can remember using one at Larkhill (Salisbury Plain Range Control) in 1975 and it was brand new, one of the first.
According to This Link Norwich Airport installed an ACR430 in 1970:-
In 1970 the Customs authorities granted approval for the export and import of all types of freight. Later that year a Plessey ACR 430 radar system was installed.
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Some interesting history here
And a sales (?) brochure for the 430 here
Table 1 in the 430 document would have been good fodder for JT to expound at the College
I have never personally worked with either a 424 or a 430 but remember watching Hurn Approach working with their 430 and flying several half-milers to 17 (also Hurn) whilst doing my instrument flying intro in a 152 - in fact it was under the hood right down to the flare as my Instructor carried on the patter once the SRA was terminated.
DD
And a sales (?) brochure for the 430 here
Table 1 in the 430 document would have been good fodder for JT to expound at the College
I have never personally worked with either a 424 or a 430 but remember watching Hurn Approach working with their 430 and flying several half-milers to 17 (also Hurn) whilst doing my instrument flying intro in a 152 - in fact it was under the hood right down to the flare as my Instructor carried on the patter once the SRA was terminated.
DD
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The son of 430 lives on at Gloucestershire (aka Staverton), does just about everything that the old 430 couldn't, including the ability to have SSR overlayed.
Still a 3CM radar, but light years ahead of its 424 grandad.
Still a 3CM radar, but light years ahead of its 424 grandad.
Norwich certainly did have the first operational ACR430 - and a dire piece of kit it was too. To say the least, it was extremely hard work for something that was marketed as a pukka surveillance radar (i.e. not just for one-at-a-time SRAs as was the 424). Word obviously had not got around by 1979 as Bournemouth Airport then bought one to replace the ACRVI that the then-CAA took with them at the end of their ATC contract. Fortunately, the excellent IAL engineers were able to improve it such that it did sterling service throughout the 1980s.
2 s
2 s
Last edited by 2 sheds; 14th Feb 2012 at 18:09.
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One of our guys will be validating on the 430 today, complete with a half miler. It's now a 'MARIS 900' with solid state transceivers and running on a Windows PC display. We had a fault last week, but a replaced modulator board and some tweaking to the triggering, courtesy of Dr Ken Collier of MARIS, has resolved that. Whilst putting it back into service, we checked some targets with Brize and could see traffic in the airway, 20 miles south at F220!
Aren't Lasham going to upgrade the 424 to a 430/Maris? I gave them our old Kelvin Hughes tubes because I couldn't bear to put them in the skip!
Aren't Lasham going to upgrade the 424 to a 430/Maris? I gave them our old Kelvin Hughes tubes because I couldn't bear to put them in the skip!
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Originally Posted by matspart3
Aren't Lasham going to upgrade the 424 to a 430/Maris? I gave them our old Kelvin Hughes tubes because I couldn't bear to put them in the skip!
Thread Starter
Fascinating to read about the history of the Decca and Plessey radars and the trials and tribulations of those people who used to work with them (or perhaps still do !)
The same phrase keeps recurring regarding the 424, i.e. "pencil beam" which I surmise means great for talkdowns (practice permitting) but not much use for general surveillance. I don't know how well the LBA 424 performed but I gather the 430 was a reasonable performer for its day, following rewiring and mods by the local Tels team. Still never found out where it ended up post- LBA though but at least the 424 made it to Brough, at least.
By the way, did Blackpool ever use a 424 ? Last time I was there (1997) I remember seeing the radar head and I vaguely recall it resembling a 424. However I also recall one of the controllers saying it was a Plessey machine so I'm not sure. It used green monochrome displays though.
Who, or what, are these MARIS folks ? Do they specialise in breathing new life into old technology ?_
The same phrase keeps recurring regarding the 424, i.e. "pencil beam" which I surmise means great for talkdowns (practice permitting) but not much use for general surveillance. I don't know how well the LBA 424 performed but I gather the 430 was a reasonable performer for its day, following rewiring and mods by the local Tels team. Still never found out where it ended up post- LBA though but at least the 424 made it to Brough, at least.
By the way, did Blackpool ever use a 424 ? Last time I was there (1997) I remember seeing the radar head and I vaguely recall it resembling a 424. However I also recall one of the controllers saying it was a Plessey machine so I'm not sure. It used green monochrome displays though.
Who, or what, are these MARIS folks ? Do they specialise in breathing new life into old technology ?_
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Maris have developed a variety of mods and upgrades for pre-loved radars, including the 430 and, more recently Marconi 511s. They provide and maintain kit all around the world, including a number of UK military weapons ranges. Ken Collier is the main man and is a genius. What he doesn't know about radar isn't worth knowing.
Our man passed today
Our man passed today
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Originally Posted by Mooncrest
people who used to work with them (or perhaps still do !)
Originally Posted by Mooncrest
The same phrase keeps recurring regarding the 424, i.e. "pencil beam" which I surmise means great for talkdowns (practice permitting) but not much use for general surveillance.
"if the blip is temporarily lost....the beam has but to be depressed or raised to pick it up again"
It's a horrible feeling when that blip disappears with a ULE examiner standing behind. Bit difficult to explain to him that one gets used to vectoring 'parcels of thin air'..."don't worry, it'll re-appear" is no longer acceptable!
If there are two blips in the beam they could be somewhat close...
If there are two raindrops in the beam you might as well go home...it's a great weather radar!
It's also fine in CAVOK...when the crews don't need radar...
Originally Posted by matspart3
Our man passed today
Originally Posted by matspart3
One of our guys will be validating on the 430 today
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The pencil beam is very thin. Nowadays this necessitates (or should necessitate...) re-ident...
It's a horrible feeling when that blip disappears with a ULE examiner standing behind.
It's a horrible feeling when that blip disappears with a ULE examiner standing behind.
By the way, did Blackpool ever use a 424 ?
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I always found that putting a finger on the screen to help keep track of the target was a great technique
On the beach
The SLA-1 (3cm PAR) needed more hands than three.
There were two tubes, one for elevation one for azimuth. On each tube you had two buttons for servos (up/down and left/right) and a two way self centring switch for gain control.
With your remaining hand you wrote down the headings with a chinagraph!
There were two tubes, one for elevation one for azimuth. On each tube you had two buttons for servos (up/down and left/right) and a two way self centring switch for gain control.
With your remaining hand you wrote down the headings with a chinagraph!
@ On the Beach
These'll be familiar then
Chinagraphs.jpg picture by oldbloke60 - Photobucket
Still in daily use after 40+ years - only trouble is that I can't get yellow refills now so stuck with black !
These'll be familiar then
Chinagraphs.jpg picture by oldbloke60 - Photobucket
Still in daily use after 40+ years - only trouble is that I can't get yellow refills now so stuck with black !