When I purchased my R109 in the mid 1950s, it was to me the ultimate receiver. Not only it operated on a 6 volt battery which was very useful at the time, it covered both 80 and 40 meter amateur bands, it made a mysterious noise (the vibrator), it cost not much and, most important, its appearance was very exiting. I still have got this receiver and kept it working during the time. I used the R109 in the 60s during radio amateur field days (with a home brew transmitter) powered by a small 6 volt battery. The R109 was developed in about 1942 and uses the receiver part of the No. 21 Set. See the photo of this set in the Wireless Set No. 21 section. Operationally it was used as a stand alone field reception set and also in conjunction with Wireless Sender No. 76.