The sets were designed for remote control in aircraft and were somewhat limited in their usefulness after the war, when they were released in large numbers on the disposal market. Unfortunately, owing to the method of construction, they were not an easy set to modify for hobby use. Most were reduced to parts. There were a few published modifications for the receivers, but these were almost complete re-builds to enable them to be tuned using a dial.
The sets were designed for AM and CW modes.
The receiver was a 5 valve superhet, requiring 275v at 35 ma for HT and 6.3v at 1.2A for the heater supply. The IF was 460 Kc/s. Crystals ran on their fundamental frequencies. Audio output was via headphones, via an output transformer, which had provision to match at 20k ohms, 600 ohms or 150 ohms. The output was designed for connecting headsets in parallel.
The transmitter was of 3 valve design, with a crystal controlled oscillator, an output tetrode and a modulator. The transmitter required 250v at 60 ma and 6.3v at 1.3a for the heaters.
The total overall power input for the set was 5a for 12v systems or 2.5a for 24v systems.
Channel changing was accomplished with the Controller, Electric Type 4, which is similar to the well known SCR522 unit. In multi seat aircraft the A1134 intercom amp was used to provide additional audio power.
© Ian O'Toole, 2009. Page created: 28/04/03 Last updated: 14/5/2010