New Britain herald., 1927-12-09

After a number of comparative tests were carried out it was agreed that the advantages of simplex oper- ation outweighed the additional con- Nenience of a duplex installation. The simplex sets require less power, will not set up as much interference as the duplex, and more simplex in stallations can be operated within a given frequency band than those Of the duplex type.
 A great many tests were made with the preliminary equipment along the Mohawk division of the New York Central railroad. Very successful telephone communication was carried out and many instances were recorded where great assis- tance was rendered because such communication was ayaila ble. Much interesting data was secured with regard to transmission phenomena. Fading such as commonly occurs in nroadcaSting, or wherever transmits sion over Considerah hle distance is at
 IIlL pAIiE N'lto itbl triht lA4Gtf "iAI the train sets. Communication is. however, interrupted or reduced in volume, by the presence Of steel bridges or signal towers along the right-of-way. While the effect of such structures on the received sig nal is equivalent to fading. It might more properly be classified as shield ing or absorption effect. When the locomotive antenna is directly be heath 8. steel signal tower there is likely to be marked reduction in the strength of the received signal at the ca aboose. If transmission takes place from the caboose under those conditions it is still more difficult to receive in the locomotive. As long as the locomotive or caboose antennas are not directly beneath steel struc- ture, no apparent reduction in sig nal is obtained. Curves along the right of-wav do not have any ap- parent effect on the transmission,nor do passing trains seem to exert any interfering influence,
 Weakness Adjusted
 After operating the first set for a period of months. under actual run ming conditions mechanical weak nesses in the first set were worked out and several improvements made in the circuit and in the calling sys- tenn.
 The metal box enclosing the transmitter and receiver, is made of steel boiler plate. welded together and Is intended for installation on the deck of the tender. It is com pletely weather tight, being made to exclude water or other foreign ma terial. The equipment is built for simplex operation only. and a relay is provided on the front panel for interchanging the circuit from trans mission to reception and vice versa. The entire assembly is supported by eight springs, and in addition q sys- tenn of snubbers is provided to pre- vent oscillation.
 The transmtter compartment con- tains three of the 50 watt size tubes ana Olle OL tlt l. Watt iIbto. Four of the latter size tubes are used in the receiver. The 1-2 watt tubes are the standard tran control type which are already in use on many railroads. The 50-watt tube is known as type UN-211 and is a standard design used for aircraft and marine applications for a num- ber of years.
 The power unit for the equipment, which contains the necessary dyna- motors, filter condenser, reactors, etc, is housed in a metal contalner Two dynamotors or bearing mo- tor generator sets are utilized. The larger one only operates when trans mission is taking place, and supplies plate voltage at 1000 volts d. c. to the transmitter. The smaller ma chine runs al all times when the equipment is on the road and de- liFers plate voltage and bias voltage for the radio receiver. The use of this smaller machine permits the elimination of all batteries.
 An especially strong type of loud