Work with the army and when they come up with the tachymetric director for their 3.7-inch AA gun, use it for the next generation of RN AA gunnery directors.
This is Post 86 dated 23rd February 2018 from the thread
"British Navy Pre-WW2 Improvements" and is sort of the Army working with the Navy when they come up with radar several years before Robert Watson-Watt.
***** ***** *****
In his book
"Night Fighters", Bill Gunston has a section entitled,
"Notable Riddles of the Sky".
He wrote that the Kriegsmarine (strictly speaking still the Reichsmarine) began development of radar in 1933 after deciding if it worked underwater with sonar it could work above water with what became radar. His Majesty King George V suggested it in 1931 after learning about asdic at an Admiralty lecture, however the lecturer thought it was not possible. He also wrote that the Royal Navy's Signals Establishment had suggested a 50cm radar in 1931. Meanwhile the Germans had developed a naval gunnery radar and was fitting it to large warships, but the Royal Navy did not get any until 1941. Seekat was joined by Freya an Early Warning set. It was mobile, had 360 degree coverage and a range of 75 miles. They also had Würzburg a Gun Laying set for flak. These 50cm radars were the best mass produced sets in the world before World War II. By comparison British radar development did not begin until 1935 and IIRC the Royal Navy did not begin development of the proposed 50cm radar first proposed in 1931 until 1936.
So what if ITTL the lecturer's reply to KGV's question was,
"That's a very good idea Your Majesty! I'll look into it." He has a word with the CO of the Signals Establishment who replied,
"Funny you should mention that! Because..." and with the aid of TTL's larger Navy Estimates 1929-30 to 1935-36 that gets the ball rolling?
As there is less urgency (and less money) in the first half of the 1930s than the second (even in this TL) beginning the development of 50cm radar in 1931-32 instead of 1935-36 only pushes the state of the art forward by 2 rather than 4 years in 1939. That's still good enough to have British warships fitted with 1941-42-OTL standard 50cm radars in 1939-40-TTL.
IMHO it's a dead cert that the Army will buy 50cm Gun Laying (GL) and Search Light Control (SLC) radars derived from the Admiralty's research than the GL Mk I, GL Mk II and SLC radars developed IOTL by the Army cell at Orfordness. These 50cm sets ought to be far more effective than the sets available to AA Command in the Battle of Britain and Blitz. I also think that the TTL GL and SLC sets would come into service a year sooner than the OTL sets and therefore be available in much greater numbers during the Battle of Britain and Blitz.
I think a 50cm Airborne Interception (AI) radar for night fighters would be far more effective than the OTL AI Mk I to IV systems of OTL which IIRC used the 1.5 metre wavelength. I also think that it would be available in large numbers a year earlier than the AI Mk IV. Now we need to bring the Beaufighter forward a year or find an equally effective substitute which can be in large scale service by June 1940.
OTL the British night defences didn't shoot down Luftwaffe aircraft in significant numbers until the last 6 weeks of the Blitz (April and the first half of May 1941). TTL the RAF and AA Command would be doing so from day one of the Blitz.
