A receiver which was an integral part of the TCS system.  To best show this WW2 American addition to our W/T suite, we have produced a PDF file which shows the whole system, including a close-up of the RECEIVER. The file is also shown on the TRANSMITTER matrix also.

The receiver turned out to be a problem, and a very real problem too.  Superhet receivers have a local oscillator which mixes with the RF stage to produce an IF stage[ Intermediate Frequency], the very essence of heterodyning.  Unfortunately for us [all and any communicators using this receiver] the LO was a pretty powerful oscillator which not only oscillated as part of the heterodyne system, but also oscillated direct to the aerial.  The original system worked in simplex mode i.e., it had a send/receive relay controlling the use of one aerial.  When not transmitting for real [an intentional event] the relay biased itself to the reception side connecting the aerial to the receiver and its RF stages.  Whilst in this position, it transmitted the output of the LO [rather like a TV receiver does which the proverbial TV Licence Monitor Van can so easily read/intercept and thus pinpoint] and unwittingly broke the rules of RADIO SILENCE.  The LO could be D/F'ed even though every Morse key and Pressel switch in the ship was isolated [by order]! It soon became obvious that either a modification had to be performed on the front end of the receiver or that the receiver had to be disabled.  The Royal Navy chose the disabling and quite often removed the TCS receiver from the system fit.  There was a precedent ! If you look through the scuttle called TUNER AMPLIFIER B9 {written in 1928} you will see why a receiver, without a 'harnessed radiation', couldn't be issued to the Fleet for use where there were many ships together in formation.  Once a D/F fix had been made on the hapless radiating ship, all ships in company would have been targeted as one group.

Fitted widely throughout  the Fleet which included submarines.

Click here TCS.pdf for a description, and here FULL TCS SYSTEM.pdf for system.  In this file you will see a good picture of the receiver and its connections in the system. The second picture in this file is the TCS Transmitter and the third and final file is the TCS Receiver.