This is a mid-sixties era solid-state BA. It still has 6 tubes, the nixies in the frequency readout. Photos by Robert Nickels, Roy Wildermuth, Todd Roberts and me. According to the tags, the earlier R-1451 was part of the "Water Boy 1" system, while the R-1451A was part of the WLR-6. The R-1449 VLF receiver is part of the same systems.
The R-1449 is allegedly a repackaged CE/Watkins-JohnsonI 357. The R-1451 also has modules similar to the R-1449, and may be a repackaged CEI/W-J or other manufacturer's receiver.
Additional front panel detail photographs here and here.
Basic specs are:
0.5 to 32 MHz in 6 harmonically-related bands. There is an AFC circuit that can be tuned to lock the frequency on any 100 Hz multiple.
Single conversion 0.5-8 Mhz, double conversion above 8 Mhz.
IF filters for 16, 8, 4, 3 (ISB only), 2, 1 and 0.1 KHz bandwidths. Clevite ceramic filters are used for 16, 8, 4, and 2 KHz. Collins mechanicals are used in the ISB module. The 1 and 0.1 KHz bandwidths are obtained with single crystal filters. A broadband 455 KHz IF output is provided on the rear panel, in addition to separate AM/CW/LSB and USB audio outputs.
AM, CW/SSB, ISB and (R-1451A only) "FMA" modes.
Another interesting feature is a retractable spinner-crank on the inner tuning knob. The outer knob is slow speed reduction tuning, inner knob high speed tuning, and pull the spinner from the center of the inner knob -- it extends on an arm for really high speed tuning. Interior construction is modular, but very cramped.
Sylvania made and prototyped other HF receivers. Examples include the R-1414 and an even earlier 26-tube receiver similar to the R-390 or R-725/URR.
Michael O'Beirne, G8MOB, has pointed out many similarities between the R-1451 and the Telefunken E-863. Both have harmonically related bands, 100 Hertz AFC, and Nixie tube frequency readouts. The E-863 is also listed as a surveillance or communications receiver. The IF frequencies are different, and the E863 lacks the R-1451's lowest MF band. There may be a relation between them..........
Please contact me, Robert Nickels, Roy Wildermuth, and Todd Roberts if you have any additional information on this series of radio.