Oxford-Tartak Model N3B Receiver (U.S. Navy)


      Transmit switches on the bottom for a remote control of a companion transmitter. The right hand knob selects internal crystals for control of receiver frequency or the receiver VFO.
This N3B receiver was part of the NAE-3 radio group.

   Q.  Was this system designed for Aircraft or just ground mobile use?


              Photo and chassis layout by Dave Stinson AB5S


     Dave did extensive testing of the receiver and provided these notes:

     On the slight chance that one of you has this unusual and interesting receiver on a shelf and wants to get it running, write me. I've just resurrected one and can likely save you some head-scratching. It's a "not-quite-a-clone" of the RCA AVR-20 receiver. The front panel graphics and Volume / LO source knobs are clearly derived from RCA AVR and SCR-288 patterns. Tuning knob in the photos is not orginial, but wear patterns indicate the same knob as used on the AVR-20 and I've so replaced it. LO wiring and RF Amp tube type are different, as is the power distribution and 6-Volt-only fil. wiring. Three cap replacements, repair of the LO coil and tracing the weird power distribution and it's playing fine on about 150 VDC B+. I'm thinking of pairing it either with an RCA AVT-111 (not the -112; the earlier -111) or with one of the little Ranger or Lear transmitters, which might be more interesting.

 Power connector: Pin1 - 6 V Fil.
                                   5 - Grnd
                                   7 - B+ Must connect 56K 1/4 watt resistor between pins 6 and 7.
                                        This provides B+ to the Local Oscillator.

   The IF is 455 KC and is fairly sharp. Audio out is matched for 600 ohms. B+ of 150 Volts delivers plenty of audio and RF sensitivity. AVC circuit works well for AM, but front-end easily overloads when the BFO is turned on.

                      Dave AB5S

         Indicator lights at the top for receiver and transmitter.
                                    Tower frequency 3105 as well as 3345,6690 kc.
                FT-243 crystals
                                RCA AVR-20 Front Panel Comparison
                       RCA AVR-20  (AB0CW photo)                       Oxford Tartak N3B
                  Oxford Tartak N3B bottom chassis
       Power/transmitter and Microphone connections.

                             N3B   Slightly larger than the RCA AVR-20

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