AMES Type 8 - PPI or not?

[Maury Markowitz]

I'm reading over the little material I have on the AMES Type 8, and I'm coming to conflicting conclusions...

Much of the material discusses the Type 8 as a precursor to the Type 7, and there's considerable discussion of the PPI. This suggests that the Type 8 had a PPI.

But at the same time I have a description of how the Type 8 antennas were directed to an angle using a ship-telegraph-like system. This suggests that it was a line-of-shoot system.

Of course it also appears that Type 8 stations had two antennas, so perhaps one scanned and the other pinpointed?

Does anyone have a reference that clears this up?

 

[RHVERNON]

There were various versions of GCI radar known as the Type 8. The First version used in the first half of 1941 had two aerial system on two turntable cabins set apart. One was the Transmitter aerial and the other was the receiver one. TRE had not yet worked out how to build a Duplexer TR switch when the equipment was designed in mid 1940. The Radar used a PPI display attached on the Receiver side, plus the Receiver aerial was spilt in two to provide high finding on a second scope. The two turnable cabins were rotated by pedal power with the telegraph system, like that to set ships speed between the Bridge and the engine room. However this system showed the angle of the cabin it was in, plus the angle of the other cabin. Of course, both dials showed 360 degrees and the cabins were aligned so that 0 degrees was north. The two personnel who were doing the leg work had the job to keep both needles aligned on their dial at a constant speed and sweep the two cabins between two angles that covered the target and the interceptor as ordered by the Controller on the PPI scope (it was used in a sector search mode and not a 360 coverage mode, though it was totally capable of doing it, sector search gave a faster data rate). T/R Switches and Motor drives started to appear by mid 1941 and later versions had two aerials on top of and below for height finding. US Army had a copy of the original Type 8 with a bunch of improvements known as the SCR-527. https://www.armedconflicts.com/SCR-527A-radiolokator-t81161

 

[Maury Markowitz]

Just saw this now. Most useful, thanks!

 

[RHVERNON]

The Radar Museum at Neatishead has some photos of the inside of an early Type 8. The cabins were hand cranked, not turned by foot power and the aerial position telegraph is in one of the photos (The photos are on display boards that once belonged to Marconi). PPI display was rotating coil type with a 9-inch CRT. The long duration phosphor on the CRT came out of an Anti-Jamming display system developed for Type 1 CH. As well as having PPI on the Type 8, there was a program to modify the Type 2 CHL to a common standard starting in mid 1941. The early CHL radars were basiclly lashed up systems to get the system operational in 1939/40. In mid 1941, a redesigned system call CHL Mk 5 had its design frozen so that all of the UK systems could be modified to a common standard. These modifications included 360 degree motor drive with a single antenna fitted with a TR switch. a high power transmitter with 60 mile range and a PPI display system. 5 sites were modified to Mk 5 standard by the end of 1941.