AN RAF R1155 AND A ROBOT VACCUUM CLEANER!

Aaah, the venerable R1155, the receiver every romanticised collector likes to have, their opinions guided by historical significance underscored by films such as The Dam Busters and Crooked Sky.

For those not "in the know" the R1155 is an English LF and HF superheterodyne receiver, manufactured by Marconi, Ekco, Plessy, Philips, and the Gramophone Co. (EMI). which was  widely used by the RAF during WW2.  It covered a frequency range of 75kHz to 18.5mHz in 5 bands, with D/F (Direction Finding) and homing functions.

This receiver started development in 1939 by the Marconi Wireless Telegraph Co and was called the AD.87B/8882B to replace the pre-war T1083 and R1082. The RAFdesignation was the R1155 and the  corresponding transmitter was the T1154, the first units being installed in June 1940 and remaining in use well into the 1950s.   They were fitted to many aircraft like the Avro Lancaster and the deHavilland Mosquito. . Although they were used mainly in aircraft, later in the war they were fitted to small boats (N suffix), and also to vehicles (115, 115B, 130, 131).

The receiver has 10 valves of which 3 are for the D/F and one is a Tuning Indicator (magic eye). There are 6 used for the superheterodyne receiver. The receiver has an RF stage, a mixer/oscillator, two IF stages, an AVC and BFO stage, a detector, an audio amplifier, and a magic eye tuning indicator. The D/F circuitry has two valves as aerial switching and multivibrator, and a meter switch. It can have 3 aerials, a fixed wire type, a trailing aerial, and a D/F loop. It has 11 controls of which 5 are for D/F only.

If we can focus on one of the valves in the lineup, lets have a look at the MHLD6, also known as CV1101, equivalent to DL63 and also known by inter service parlance as VR101.  This bottle did duty in this receiver in the  AVC stage, the  BFO stage,  the amplifier stage and also as a detector - pretty good huh? 

Interestingly, although the VR101/MHLD6 is pin compatible with the DL63 but has twice the heater current requirement at 0.64A when compared to the paltry 0.3 A required by the DL63.

Although a versatile device, imagine my surprise when Mrs Mullard Magic stridently demanded a VR101 of her own.  SHE WANTED ONE and she was going to HAVE ONE.

Alas, the VR101 I pulled from our stock and wrapped with a pink ribbon around the valve base before presenting it to her was not quite what she had in mind.......   her preferred VR101 looked like this one:-