Radiomarine Corporation of American (RCA)  -  RAZ-1 (AR-8503, AR-8503-P, RM-6)

 RAZ-1 was the Navy designation for a group of equipment consisting of a four tube longwave TRF receiver with regenerative detector, a matching one tube preselector and a one tube AC power supply - all built for shipboard use. The Navy number for the receiver is CRM-46092 but it was also known as the AR-8503 in commercial applications. The receiver circuit uses one RF amplifier, a regenerative detector and two stages of AF amplification. The one tube preselector is Navy number CRM-50092 or commercial number AR-8503-P and the AC power supply is Navy number CRM-20096 or commercial number RM-6. Tuning is from 15 KC to 600 KC in four bands. The Preselector was used to reduce regenerative signal radiation to the antenna in addition to increasing sensitivity and selectivity. The National Type "N" dials are 0-100 scaled with 180 deg. rotation and the calibration chart is on top of the receiver. The RAZ-1 could be operated from batteries if necessary. The receiver and preselector panels are beautiful machine-textured aluminum with a matte-chromium finish. The receiver case is copper-plated steel under the gray wrinkle finish and uses "shock-mount" feet that were screwed to the operating table, (the pre-selector and power supply were normally screwed directly to the operating table.) The Navy contract is dated December 2, 1941 - just five days before the attack on Pearl Harbor. The RAZ-1 equipment shown are all assigned serial number 65. Performance of this operational RAZ-1 is incredible with an ability to extract weak signals out of the noise that is impressive. The photos below show more detail on the receiver and the preselector.