Collins Radio Company, Cedar Rapids, USA
651 S - 1
überarbeitet am 31.12.2010
The 651S-1 communication receiver has been constructed by Collins in 1971/73, this modular constructed rugges and very reliable solid state receiver has been sold to many official services (as the U.S. Coast Gard, U.S. Air Force) in many different variants.
The Collins 651S-1 is a solid state communications receiver in modular construction, the triple conversion superhet with phase-locked lop synthesizer could be remote controlled and was available in several configurations, it was to replace the venerable hollow state 51S-1.
The receiver comes in a metal desktop cabinet, there was also a rack version
used by several U.S. services. The desktop cabinet is33,3 x 15,9 x 38,7 cm wide
and the receiver has a weight of 13,56 kg.
In the upper part of the front panel, you find at the left side the signal
strength meter calibrated in dB and at the right the digital frequency display
with an accuracy of 100 Hz, the nixie tubes in very early sets have been replaced
be LEDs mounted on nixie tube sockets in later sets and fixed wired LEDs in
the latest receivers.
Operation of the receiver is fairly easy: connect a decent antenna to the antenna socket at the rear, an external speaker or some headphones and the mains cable and turn the set on with the POWER switch to OPER. The AGC switch should be set to FAST, RF Gain fully clockwise in the maximum position and the CONTROL switch in the LOCAL setting. You will hear the quite noisy cooling fan of the receiver, then use the rotary controls to select the MHz and 100 kHz digits of the desired frequency and use the main tuning knob to tune the radio, the annoying hiss when tuned to an empty frequency is witness of the very high receiver sensitivity, the receiver will be much more quiet when tuned to a station with a sufficient signal level.
The Collins 651S-1 is quite a rare bird, at least here in Europe: it's one of the last "real" solid state radios made by Collins and performs very well on the bands, the 2,7 kHz SSB and 3 kHZ AM filters are well suited for poor conditions on the tropical bands and the 6 kHz AM bandwidth is well suited for program listening. Well, there is no passband tuning, You might find an external audio notch filter as the ones from Dierking useful and the 651S-1 has no programmable frequency memories, but it's a great receiver for cruising the bands and a rock solid performer.
© Martin Boesch, 31.12.2010