Editing Chain Home (section)

===Experimental system===
[[Edward George Bowen]] joined the team after responding to a newspaper advertisement looking for a radio expert. Bowen had previously worked on ionosphere studies under Appleton, and was well acquainted with the basic concepts. He had also used the RRS' RDF systems at Appleton's request and was known to the RRS staff.{{sfn|Bowen|1998|p=8}} After a breezy interview, Watson-Watt and Jock Herd stated the job was his if he could sing the [[Hen Wlad Fy Nhadau|Welsh national anthem]]. He agreed, but only if they would sing [[National anthem of Scotland|the Scottish one]] in return. They declined, and gave him the job.{{sfn|Bowen|1998|p=9}}

Starting with the BBC transmitter electronics, but using a new transmitter [[Valve (electronics)|valve]] from the Navy, Bowen produced a system that transmitted a 25&nbsp;kW signal at 6&nbsp;MHz (50&nbsp;metre wavelength), sending out 25&nbsp;μs long pulses 25 times a second.{{sfn|Watson|2009|p=47}} Meanwhile, Wilkins and L.H. Bainbridge-Bell built a receiver based on electronics from [[Ferranti]] and one of the RRS CRTs. They decided not to assemble the system at the RRS for secrecy reasons. The team, now consisting of three scientific officers and six assistants, began moving the equipment to Orfordness on 13 May 1935. The receiver and transmitter were set up in old huts left over from [[World War I]] artillery experiments, the transmitter antenna was a single [[dipole]] strung horizontally between two {{convert|75|foot}} poles, and the receiver a similar arrangement of two crossed wires.{{sfn|Bowen|1998|pp=11–13}}

The system showed little success against aircraft, although echoes from the ionosphere as far as 1,000&nbsp;miles away were noted. The group released several reports on these effects as a [[disinformation|cover story]], claiming that their ionospheric studies had been interfering with the other experiments at the RRS at Slough, and expressing their gratitude that the Air Ministry had granted them access to unused land at Orfordness to continue their efforts.{{sfn|Watson|2009|p=48}} Bowen continued increasing the voltage in the transmitter, starting with the 5000&nbsp;[[volt]] maximum suggested by the Navy, but increasing in steps over several months to 12,000&nbsp;V, which produced pulses of 200&nbsp;kW.{{sfn|Bowen|1998|p=14}} Arcing between the valves required the transmitter to be rebuilt with more room between them,{{sfn|Watson|2009|p=48}} while arcing on the antenna was solved by hanging copper balls from the dipole to reduce [[corona discharge]].{{sfn|Bowen|1998|p=13}}

By June the system was working well, although Bainbridge-Bell proved to be so skeptical of success that Watt eventually returned him to the RRS and replaced him with Nick Carter.{{sfn|Bowen|1998|p=14}} The Tizard Committee visited the site on 15 June to examine the team's progress. Watt secretly arranged for a [[Vickers Valentia]] to fly nearby, and years later insisted that he saw the echoes on the display, but no one else recalls seeing these.{{sfn|Bowen|1998|p=15}}

Watt decided not to return to the RRS with the rest of the Tizard group and stayed with the team for another day.{{sfn|Bowen|1998|p=16}} With no changes made to the equipment, on 17 June the system was turned on and immediately provided returns from an object at {{convert|17|mi|km|abbr=on}}. After tracking it for some time, they watched it fly off to the south and disappear. Watt phoned the nearby [[Seaplane Experimental Station]] at [[Felixstowe]] and the superintendent stated that a [[Supermarine Scapa]] [[flying boat]] had just landed. Watt requested the aircraft return to make more passes.{{sfn|Bowen|1998|p=16}} This event is considered the official birth date of radar in the UK.{{sfn|Watson|2009|p=50}}

Aircraft from [[RAF Martlesham Heath]] took over the job of providing targets for the system, and the range was continually pushed out. During a 24 July test, the receiver detected a target at {{convert|40|mi|abbr=on}} and the signal was strong enough that they could determine the target was actually three aircraft in close formation. By September the range was consistently 40&nbsp;miles, increasing to {{convert|80|miles}} by the end of the year, and with the power improvements Bowen worked into the transmitter, was over {{convert|100|mi|abbr=on}} by early 1936.{{sfn|Bowen|1998|p=16}}