The LEACH BREAK-IN RELAY Model 18 Type S-3 1925-35.
Above is a Leach Break-In Relay Model 18 Type S-3 Relay and was manufactured by Leach Relay Co. 860 South Los Angeles Street, Los Angeles. California. U.S.A. Circ 1925-35. And in 1930 was priced at $25.00.
The primary purpose of this relay is to function in such a manner that it acts as an automatic antenna switch and power relay. The two being combined into one unit in a very novel and extremely practical manner. When the power contacts (which control the current in the main keying circuit of the transmitter) are open, the receiver is always connected to the antenna. Just before these power contacts close, for the next dot or dash, the antenna lead is disconnected from the receiver and completes the transmitter circuit. This action is extremely fast and even though the relay be connected to an automatic sending machine operating from 75 to 100 words per minute, the receiver will always be connected in the circuit between every dot and dash and out of the circuit while these characters are actually “going out” THIS MAKES IT POSSIBLE TO LISTEN IN WHILE SENDING. One antenna being used for the entire layout.
The advantages of such a system are very apparent and are briefly described as follows: Let us consider the old style system first. Suppose two stations NOT equipped with LEACH BREAK IN RELAYS are exchanging traffic, one receiving from the other. Now suppose this receiving operator gets interference from some source such as heavy static, other stations, local disturbances or weak signals. With this old hand antenna switch system it would not be possible for him to stop the sender. It would be necessary for him to wait until the sending operator finished his message (possibly several of them) and then ask for a repetition of parts here and there, or possibly of all that was sent. The sender then goes ahead cluttering up the ether with a lot of wasted time and energy, keeping wave bands crowded, using the transmitter much more than is necessary, delaying and interfering with other stations, traffic, etc.
Now suppose these two stations are equipped with LEACH BREAK IN RELAYS. The interference comes along, it is NOT necessary for the receiving operator to wait at all. All he has to do to stop the sender is to hold his key down a second or so and give the signal “BK”. The sender would hear this between his own dots and dashes and stop sending immediately, to be advised ON THE SPOT, whether to wait until the interference was over or where to begin sending again. Neither of these operators would have thrown a single switch in sending back and forth as this is all taken care of automatically by the LEACH BREAK IN RELAY.
Think what all this means during heavy static or interference from other sources. It means that traffic gets “through” rapidly, accurately and in less than half the time usually required with the old system.
This LEACH BREAK IN RELAY may be operated from a small Morse Key, SPEEDOPLEX No2, or any similar transmitting device. It is very “FAST” and will not “lag” or “drag”. It is designed for tube or spark transmitters up to and including 2KW.
3/8” black Bakelite base 4” x 5”. Highly polished nickel finish. Two pair 5/8” and one pair 1/8” silver contacts. Hard rubber shelled coils.
Type S-1 complete, operates on 6 volt D.C. Price - $23.00
Type S-3 complete, operates on 120 volt D.C. Price - $25.00
(Wiring diagram furnished with each relay)
The above information was taken from a Leach Equipment catalogue dated Aug 1930.