The Vampire 11 had a Rebecca 8 set, as did the Jet Provost and Hunter. In 'range only' mode, if you were lucky it had a range of about 40 nm; in 'homing' mode about 20....
The control box was a large, clunky thing with large bakelite rotary knobs. One control selected the letter and the other the number of the associated Eureka 7 channel; for example, Cranwell was C4 and Cottesmore D5 (I think). The morse coding rate for the Eur7 was very student friendly - about 1 word per week! You had to check it as it was quite common for the Rebecca to lock onto a different station to the one you'd selected.
Somehow we flew radio navigation exercises using nothing more than Eur7 and UDF, then flew a DME let down at base using this contraption. At least we had the left/right indicator, rather than the CRT screen the guys who flew Pigs had! You went outbound in the 'DME safety lane', then faffed with L/R and the DI to establish the correct inbound approach course....
Fortunately we'd all had several sessions in the Link trainer before trying it for real.
The 'swingometer' range needle used to hunt around the dial unless the Rebecca could sniff out a station; once I was just pulling off the target at Pembrey when the needle went clockwise at precisely the same rate as the g-meter's needle normally moved - except that it kept going...
For a moment I eased off the g as a reflex in case I was overstressing....fortunately I was already climbing. We used to pull out of the dive and immediately check the mirror for the 25 lb bomb smoke - having the distraction of the Rebecca needle moving round the dial out of the corner of your eye was most unwelcome!
The bandwidth of Eureka/Rebecca was colossal - about 4-5 MHz if I recall correctly. When the JP5A came in with VOR/DME, it seemed like the space age. This was about 1974! But the wonderful Gnat with its offset TACAN was truly magical! We had non-offset TACAN in the GT6 Hunters at Valley, but all bar 2 of the jets at Brawdy had the old Rebecca. The Mk9s had ADF, but no-one taught us how to use it - we just used to listen to music on it. A chum, Dick 'Whizzbang' was a bit of a culture vulture and had a memorable time rocketing with SNEBs at Pembrey whilst listening to 'Ride of the Valkyries' on BBC Radio 3!
The guys at 45/58 Sqns, RAF Wittering, had some NDB-to-DME approach system. If you were brave enough, you did the initial homing and inbound turn on NDB with the Rebecca turned off (as it interfered with the ADF), then turned the Rebecca on to fly the final approach. I wouldn't fancy doing that in a Cherokee, let alone a Hunter 9!
However, the DME let down was probably a lot easier than the CR DF 'Jet Instrument Approach Chart' I have dated 1954. The CR DF high level descent for RAF Merryfield had an initial overhead approach not below 12
000 ft and went out on 115 degM to about 25 miles to 'half initial approach altitude plus 2000', then inbound on 285 degM with a check altitude of 3500 ft - and a min app. alt. of 1350 ft. Bearing in mind the field elevation was 145 ft, this looks like rather a useless procedure. Presumably you made the relevant calls to 'Merryfield Homer' on 104.94 Mc/s (this was long before the days of MHz) and switched to 'Merryfield Tower' on 102.42 Mc/s if you were fortunate enough to become visual!