Tech Chat Seascan Radar Display unit
A few year ago I picked up a Seascan MKII maritime radar display unit, despite having a mains input, there is no power supply in the unit, mains goes out on a multi pin connector and DC power and synchronous motor drive back in. There are also belling lee connectors for IF in and out.
All I really would like to know is how to get a scan and sweep on the display, I can't find any information about this unit, other than it was made by Electronic Laboratories in Southampton. It looks well made, modular construction but I don't know much about radar equipment, a circuit diagram would be useful, but a general idea about how it might work would be a start, does anyone have any ideas ?
The CRT is a GEC F16-101LD, I can't even find a datasheet on this as it may be a clue to reverse engineering it.
I presume the rod magnet and the drive belt are part of the rotating display mechanism.
I wondered about that too. My assumption would be that the magnet draws the electron beam aside to create the 'pointer' or whatever the correct term is, and the magnet assembly rotates to generate the sweep. I'd further surmise that the sweep motor is precisely synchronised with the radar antenna, so some sort of servo/feedback loop must exist between the two?
Again though, I know nought about radar beyond the names Decca, RACAL, Ferranti, EMI, and Garmin (and others) that I'd see being proudly displayed on the antennae of the trawler fleet which once put out of Scarborough.
It could be fun to have a radar set up on your house, and scan the local neighbourhood! - "Oh look, the Jones' are taking the X-5 for spin". . . . . .
I noted whilst reading O. S. Puckle's section on timebases in Television Today that circular scanning for television had been advocated in some parts of the world - this was c. 1935. It was purely electronic though.
Having said I could not find any CRT data, I looked again and I did, so I tried a bit of reverse engineering again and found appropriate points to feed in 250Vac, 6.3V and 12V DC and a bright spot on the screen with the synchronous motor running, injecting some tone into the scan coil drive circuit gave me a pleasing sweep display, you can take a look if you are interested;