British Type 284 gunnery radar

Guns, torpedoes, mines, bombs, missiles, ammunition, fire control, radars, and electronic warfare.
dunmunro
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Re: British Type 284 gunnery radar

Post by dunmunro » Wed May 08, 2013 1:42 am

The type L12 (282) panel could output rate to the FC computer and had rate aided target follow-up; the operator matched his power follow up to the observed range rate and this was then transmitted continuously as long the target maintained course and speed. The AFCT/AFCC might not have been initially accept automatic range and rate transmission (although the GRUB and HACS/FKC could) but the L12 operator still benefited as it reduced his work load.

Gettysburg1
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Re: British Type 284 gunnery radar

Post by Gettysburg1 » Wed Jan 29, 2020 1:00 pm

Not really a reply, but some questions, connected to British Type 284 radar (of 1941).
Mr Saxton may know, I hope

I have been researching a rare Type 287 shore radar, installed in a brick tower at Harwich, England, and used for guiding the remote detonation of British mines shielding the harbour entrance (1941-43). I have read Coales's chapter on how 284 was developed, checked out the valves, found a few vague National Archive memos relating to the 284 and 287, but am still unsure about how 284 (plus other naval 600 Mhz radars worked.
1. Was the transmission sequence inside the equipment Master Oscillator to generate 50-cm carrier wave, then 500 per-second pulse generator triode, THEN "micropup" to amplify the existing carrier wave AND pulse? (I'd been assuming pulse added last).
2.Where did the resonant cylinder (this is before Magnetrons) fit in? Was it between Oscillator and pulse triodes, or before the micropups?
3.Is there anywhere I could see a photo or diagram of the early Type 287--or at any rate 284--of 1941, as opposed to later versions.

The Harwich 287 seems to be the only one with any equipment left--i.e, the 2 24-diople"pig trough" reflectors on their mount and turning base, the hand-turned shaft underneath, and the electric generator. It was never upgraded to automatic working, or dual transmit-receive aerial.

There are descriptions of this "Harwich Radar Tower" online but they are old and inaccurate and I am trying to produce new signs. Any help would be much appreciated, and acknowledged, at the Tower, which is an occasionally-opened museum.

dunmunro
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Re: British Type 284 gunnery radar

Post by dunmunro » Sat Feb 15, 2020 8:52 am

Gettysburg1 wrote:
Wed Jan 29, 2020 1:00 pm
Not really a reply, but some questions, connected to British Type 284 radar (of 1941).
Mr Saxton may know, I hope

I have been researching a rare Type 287 shore radar, installed in a brick tower at Harwich, England, and used for guiding the remote detonation of British mines shielding the harbour entrance (1941-43). I have read Coales's chapter on how 284 was developed, checked out the valves, found a few vague National Archive memos relating to the 284 and 287, but am still unsure about how 284 (plus other naval 600 Mhz radars worked.
1. Was the transmission sequence inside the equipment Master Oscillator to generate 50-cm carrier wave, then 500 per-second pulse generator triode, THEN "micropup" to amplify the existing carrier wave AND pulse? (I'd been assuming pulse added last).
2.Where did the resonant cylinder (this is before Magnetrons) fit in? Was it between Oscillator and pulse triodes, or before the micropups?
3.Is there anywhere I could see a photo or diagram of the early Type 287--or at any rate 284--of 1941, as opposed to later versions.

The Harwich 287 seems to be the only one with any equipment left--i.e, the 2 24-diople"pig trough" reflectors on their mount and turning base, the hand-turned shaft underneath, and the electric generator. It was never upgraded to automatic working, or dual transmit-receive aerial.

There are descriptions of this "Harwich Radar Tower" online but they are old and inaccurate and I am trying to produce new signs. Any help would be much appreciated, and acknowledged, at the Tower, which is an occasionally-opened museum.
You might refer to:

THE JOURNAL OF
THE INSTITUTION OF ELECTRICAL ENGINEERS
EDITED BY W. K. BRASHER, SECRETARY
VOL. 93. PART IIIA (RADIOLOCATION), NO. 2. 1946
NAVAL FIRE-CONTROL RADAR*

But it might be necessary to find a type 284 operators manual.

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Dave Saxton
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Re: British Type 284 gunnery radar

Post by Dave Saxton » Mon Feb 17, 2020 1:55 am

Radar engineer Brian Callick who was in the program:
The transmitters ( 600 mhz ) used a variety of circuit configurations based upon a self-oscillator which defined the frequency of the radiated signal, sometimes with one or two stages of power amplification between it and the aerial system. Because of the rapid rate of rise and the high peak current in the pulse, the transmitter and the modulator MD are mounted as close together as possible. The critical components are the triode or tetrode transmitter valves and the thyratron or other devices which generate the high power DC pulse...
Callick is referring to a block diagram in which the modulator is triggered by the start of the sweep across the cathode ray tube or the display. Callick notes that the trigger system was only used in some of the systems and for most of the 600mhz systems the display sweep was triggered by the modulator. If the early type 284 used the sweep to trigger the modulator or the other way I do not know for certain.

Callick pointed out that Micropups were originally designed as oscillators to operate in the grounded anode-common anode mode. This means that the anodes were at radio frequency earth potential and connected to the output leads to the transmitter aerial. Electron flow from the direct heated cathode to anodes was controlled by the grid operating at, I assume, a negative voltage. An alternative method used by Type 281 was cathode switching. The problem with the grid modulator system or cathode switching was that output power was limited to a max of about 16 kw for two micro seconds at 600 mhz.

The pulse in case of grid modulation or cathode switching could have been triggered by a hard valve modulator or by a line modulator. The term "self-oscillator" may indicate the connected modulator was initiated when the grid current or cathode current would rise and fall as the electrons across the tube flowed and stopped flow.

The later models such as Type 284M had output power of up to 150 kw. This was obtained by anode modulation. This method used a thyatron pulser to deliver a high power pulse to the anodes of the transmitter tubes. (A thyratron is a gas filled tube usually of mercury vapor.) The pulse will occur at consistent intervals as the anode current (of the thyratron) rises above the potential of the control grid, ionizing the mercury vapor.

The block diagram is: Display (trigger)> modulator> transmitter> transmitter aerial > receiver aerial> receiver (consisting of four parts)> video amplifier> display
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