These receivers have wideband IF outputs that were connected to wideband tape recorders. They were used for intercept and direction-finding operations where gangs of such receivers were used to cover a wide frequency range,
R-1230/FLR - 2-32 mc coverage with 60kc bandwidth output - triple
Countermeasures Receiver R-1125/FLR is a high-frequency, superheterodyne receiver employing
triple frequency-conversion for the reception of signals in the frequency range from 2.0
mc to 32.0 mc.
It is intended for use in special operating categories and provides a 65 kc output signal
having a 60 kc bandwidth. Receiver operation is characterized by extreme frequency
stability, permitting long periods of unattended operation. A high level of
performance can be
expected despite adverse conditions. Initial tuning is obtained
in 100 kc increments with an interpolation oscillator (in the receiver)
which provides continuous tuning between increments. The
frequency range is covered in four bands with counter-type
tuning dials which permit accurate pre-setting to a desired frequency. A special drift-canceling
circuit contributes to the receiver's high performance by canceling any frequency error as
the result of
frequency drift in the high-frequency oscillator. Drift in the interpolation oscillator circuit is
at the low frequency used.
Oscillator- Power Supply O-928/FLR supplies operating power from one to five R-1125/FLR, and includes a 100-kc crystal oscillator which provides a standard reference signal (for incremental tuning) to each receiver.
Within the specified frequency range, the R-1125/FLR output is an intermediate frequency band from 35.0 to 95.0 kc which retains all modulation of the received signals with a high degree of fidelity.
||Frequency Conversion Diagram
|R-1230/FLR with US Navy ID plate
|Chassis slides out of the rack-mounted case and also has tilt hinges.
|R-1230/FLR with Canadian Dept of National Defence ID plate
R-1511/GR - 1.35-54mc coverage with 200kc bandwidth output
|with PC board cover removed
||Reconditioned by ASA at Vint Hill Farms Station||Bottom cover removed
|Serial #129 (no top/bottom covers)
|with PC board cover removed
See also the AN/FRD-10 CDAA page
During the 1950s and 1960s, NRL demonstrated technology that permitted a radical improvement in the performance of high-frequency direction finding (HFDF) networks and oversaw the deployment of this technology in Project Boresight and Project Bulls Eye.
The first of three innovations that underlay this work was retrospective direction finding. Previously, all stations in an HFDF network were required to measure characteristics of the same signal while transmission was still occurring; after-the-fact measurements were needed. Previous attempts at NRL and elsewhere were limited by storage bandwidth and recorder instabilities. Recording significant fractions of the HF spectrum and using a digital method for overcoming recorder instabilities enabled retrospective DF. This was the basis of the 1960 quick-reaction Project Boresight that deployed the AN/FLR-7 and AN/FRA-44 worldwide.
The second innovation was the use of circularly disposed wide-aperture direction finding arrays, which significantly increased HFDF location accuracy and signal collection. In the 1950s, NRL constructed a 400-ft diameter electronically steerable array and perfected the underlying technology. During Project Bulls Eye, scaled-up versions of this prototype were deployed worldwide by the Navy as the AN/FRD-10.
The third innovation was the use of computers for control of the HFDF network and for the prompt triangulation of target locations. To achieve high computer reliability in the pre-integrated-circuit era, a novel architecture of closely coupled shared-memory multiprocessors was reduced to practice and was deployed as the AN/GYK-3.
Project Boresight’s crucial contribution to national defense was recognized by the awarding of the Distinguished Civilian Service Award to NRL’s R.D. Misner and M.J. Sheets. The more ambitious Project Bulls Eye deployed the second and third innovations and improved the first with the AN/FRA-54 and the AN/FSH-6, thereby making HFDF a principal means of global ocean surveillance, with special capabilities against critical targets.