Sounders and Relays and Galvanometers.

Pictured above of a Magnificent Morse Sounder made in Silvertown ( E. London) Pre 1880. The two large coils of the electromagnet attracted the steel pole piece, across the top, pulling the brass lever down and giving the characteristic click. The sound was often amplified by placing the sounder in a wooden case. Operators found that they could decifer the incoming morse code signals just from the clicks !

Two views above of a beautifully restored Sounder owned by Roy / G4WPW. Labelled "ATM Co. LIVERPOOL".
Here is a quote from restorer Roy: "The base has been re-polished as have all the brass parts, they have also been re-varnished. It took about 70 hours work in all, the whole sounder comes apart quite easily,the coil wire guage is 28 swg the resistance is around 20 ohms"

Air Ministry Sounder Relaying. Here's all the info I have, kindly sent to me by Tony Smith / G4FAI and extracted from his article written in Morsum Magnificat.
  • " Type B was used for remote control of high power W/T (Morse) transmitters, including transmitters T.70 and T.1087. The morse code operator could be many miles away from the transmitting site, and this instrument, connected to the site by telegraph wires, faithfully followed his/her Morse keying to operate the transmitter. Concurrently, two type A models, of slightly different design, were used for switching HT and LT power supplies in the transmitter and receiver. Both models are polarised and differentially wound. Type A (Ref. 5B/117, later designated 10G/117). Power supply: 24v (12-0-12v). Coils 500+500 ohms in parallel. Two used for switching HT and LT by remote control. Type B (Ref. 5B/138, later designated 10G/138). Power supply: 14v ac through a bridge rectifier. Coils 500+500 ohms in series, slugged with closed metal rings round the coils. Used for keying a transmitter by remote control. According to the RAF Museum, Hendon, Type B (10G/138) was a stock item in RAF Stores until “some time after 1959.” Tony Smith / G4FAI .

    Above left can be seen two Galvanometers. Both are GEC (General Electric Company). The one on the left of picture has the following info inside: "Galvanometer No 14471. Thick Wire Res. 0.32 Ohms. Fine Wire Res. 488 Ohms. 0.0045 Amps Deflect Needle 45 Deg. Stamped in the wood casing is "14471". The right hand picture shows the inside of the other one. With hand written "8/AP 09. GEC 5738." The label gives Thick Wire Res. of 0.119 Ohms, and the Fine Wire Res. of 508 Ohms. Galvanometers were used to measure electrical current, and as one is dated 8th April 1909, I assume are from this period.

    229..... An early American sounder made by MESCO. The frame is made of cast metal and most of the parts are brass. On the arm is stamped MESCO inside an oval.


    230..... The grandest sounder around! The British GPO sounder. This one is in superb condition. pre 1880's. It has 900 stamped on the base, that stands for the 900 Ohms resistance of the coils (thanks Ron McMullen), and "GPO 21014" on the brass work.


    231..... American sounder made by Western Electric. The black base appears to be made of wood, and has "SOUNDER 3B 20 OHMS" printed on the side. On the arm is printed "WESTERN ELECTRIC MADE IN USA".


    232..... British sounder from A. W. Gamage Ltd. London, England. Also stamped on the wooden base is "20 OHMS".