This group was headed by one Gene Senti, W0ROW, of – among other things – KWM-1 and 30L-1 fame. At the time that these products were developed, and for many years, the same engineering group had responsibility for the HF commercial as well as amateur radio communications products. The 51S-1 was not part of the original package of defined S-Line products. Yes, of course, they too can function anywhere from 3.4 to 30 MHz when re-crystaled. The 51S-1 variants are all continuous coverage (with up to triple conversion in some frequency ranges), while the various members of the S-Line family of receivers are double conversion and ham band oriented. It does share many features, including the styling of the cabinet and the PTO size and style, but the 51S-1 PTO is a 70K-7 as opposed to the 70K-2 used in the S-Line family. From an architectural perspective, and from a construction and fundamental mechanical design standpoint, it is also very different from an S-Line receiver. It is better thought of as the next model following the A-Line era 51J-4 (and never introduced 51J-5, see Q3 2013 Signal). This receiver, while appearing to be a member of the notable “S-Line Family”, is not really an S-Line receiver at all. The -1B is a rare bird – indeed.įor a Detailed Physical & Operational Description – Click Here or click on the Equipment of Collins Radio on our Home Page and follow the Grey Box trail. The 51S-1B is similar to the 51S-1, but has a rear-mounted junction box that provides military-type connectors for power, control, audio, and antenna lines. The rack-mounted AC version is model 51S-1F, while the rack-mounted DC version is model 51S-1AF. The 51S-1A is similar, except that it is fitted with a 28-volt DC transistorized power supply. The more common models of the 51S-1 are mounted in a perforated wrap-around cabinet and equipped with an AC power supply capable of 115 or 230 volt, single-phase, 50 to 400 Hz operation. Coverage is continuous in thirty 1 megahertz bands. The 51S-1/1A/1F/1AF/1B receiver is designed for USB, LSB, AM, and CW signals in the range of 0.2 to 30.0 MHz. Copyright 2013-2016 Collins Collectors Associationĥ1S-1/1A/1F/1AF/1B RECEIVER – An Overview