Ss. S. MALOLO More than 1300 vessels are serviced by RCA —Because the service of the Radiomarine Corporation of America is unsurpassed in efficiency and unequalled in completeness —remarkable for its economy and reliability Sixteen distinctive features of the RCA Radio Direction Finder 1. Eight-tube Super-heterodyne receiver, using UX-201-A tubes, giving maximum sensitivity and selectivity. 2. Enclosed loop. Loop enclosure and support constructed entirely of non-corrosive silicon- aluminum. 3. Wires in loop are shielded by metal covering from the effects of stacks, stays, masts and other metal objects. This improves accuracy in readings. 4. Mechanical compensator. Permits direct readings without reference to calibration chart or correction curve. 5. Reading glass magnifies scale on the com- pass card enabling bearings to be read with greater speed and accuracy. 6. Exide battery which is automatically trickle- charged when receiver is not in use. The only attention required is the addition of water about once in six months. 7. Compass card engraved with both degrees and points of the compass. Illuminated by electric light at night. 8. Automatic signal to radio room to notify operator to open antenna switch, and positive inter-lock between opening of antenna switch and direction finder through a relay in the di- rection finder filament circuit. This device in- creases accuracy. 9. Balancing device keeps readings to absolute zero to within one degree and permits even an unskilled person to read bearings with accuracy. 10. Vertical hand wheel in the chart room oper- ates loop easily—even during a heavy gale or violent pitching and rolling of the ship. 11. Ball-bearings are used throughout on the loop drive shaft and control wheel. 12. Highest quality materials and workman- ship throughout give the instrument a fine appearance and assure long life and minimum maintenance. 13. Variable sensitivity permits bearings at close or distant ranges. 14. Dumb compass is interchangeable with the Sperry repeater permitting installation of repeater if desired. 15. Controls mounted on a slanting panel afford easy manipulation of the receiver. The control panel is illuminated for night use. Station selector dials are calibrated in meters so that the operator may turn quickly and ac- curately to the wave length desired. Control panel is provided with a cover equipped with a lock so that the entire instrument, in- cluding the receiver controls, may be locked to prevent tampering by unauthorized persons. Closing the receiver cover automatically turns off the tube filaments and puts battery on trickle charge. This is another means of assur- ing that the battery will be fully charged at all times. 16. The RCA Radio Direction Finder is backed by the name and reputation of the Radio Cor- poration of America—your assurance of the finest instrument obtainable. Complete RCA Service includes 1. Equipment—transmitting and receiving equipment of the vacuum tube type; radio direction finder. 2. Service on equipment—regular inspec- tions at any of sixteen ports; maintaining at principal ports stocks of spare parts for repairs and renewals. 3. Operators—detailing of experienced oper- ator personnel to the ships. 4. Coastal stations—Maintenance of thir- teen coastal stations on the Atlantic, Pacific, Gulf and Lakes, for prompt, efficient handling of radio traffic. 5. Accounting—Checking and settling of accounts. 6. Licenses— procuring of government licenses. Radiomarine storerooms and service sta- tions in charge of radio men of long ex- perience are located at the following ports: Boston . New York Philadelphia Baltimore Norfolk . NewOrleans . Port Arthur . Galveston Los Angeles . San Francisco . Seattle . Honolulu Cleveland Chicago . Buffalo . Duluth. Radiomarine coastal stations are located at the following points: Chatham, Mass. New London, Conn. . East Moriches, L. I. New York, N. Y. . Tuckerton, N. J. . Balti- more, Md. (city station) . .Galveston, Tex. Los Angeles, Cal. . San Francisco, Cal. Chicago, Ill. . Cleveland, Ohio . Buffalo, N. Y. . Duluth, Minn. . MARINE REVIEW—April, 1928 49