The R-1451 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
receiver is part of the same systems.
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. The receiver supports AM, CW/SSB, ISB and (R-1451A only) "FMA" modes of reception.
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.
The model number is not stated on R-1451 serial number 4. Each individual module and circuit board is also serialized in single digits. The label plate says "Sylvania HF Manual Receiver, Part of Water Boy 1 System". The corresponding tag for this R-1451A shows it as part of WLR-6 ESM suite.
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.