Welcome to the Sheltered Communications Systems Restoration Site

(Rockwell-Collins and others)

Last updated: 12 July 2020

Our Site public interest and security notice

Please note to ensure that we all understand the purpose of this web site is only to share ideas and experiences about Rockwell-Collins (and in some cases, equipment from RF Harris) technology used during the Cold War period. All of the information within this site is freely available on other web sites. All that we have done is collect the pieces that were interesting to us from the public web and put them in one place. There are many special interest web sites on older military technology similar to this one. Our primary interest is a communication technology that was initially designed in the mid to late 1960's so it is clearly NOT relevant to modern use (but the same functionality but not the technology).

To those individuals within the Government sector who may think that this information is harmful to you, please note that within a few hours on Google, Bing Search, "Fast", and "Ask Jeeves", you can find all the same information AND in most cases, in far more technical and operational detail.

All of the systems mentioned here are at least 10-15 years old and many are more than 40 years. We do not have that much interest in "State of the Art" military HF as in general; the military is often five years behind the commercial world in modern HF systems.

If you feel something should be removed, please send a mail to the contact information at the bottom of the page. We actually do not add some material as we did not think it was in the Public Interest to be shown here.

The commercial and military HF evolution story in the 1960-80's... (As we understand it)

This time in our recent history was an exciting time with many radical changes in our societies. From the pressures of the "Cold" war to the changing of the how people interacted with each other. As an example: people began using the airlines in much greater volume to explore the world and thus, the world became smaller. People measured how long it took to go from place by hours and not days and weeks as it had taken 50 years before. In the background, the HF and VHF communications systems were the key to the coordination of moving the people on their holidays or moving people off to the war front. Many countries ran extensive global HF networks to move diplomatic messages between their missions and to allow their countries to have more effective national communications. The 1950's to the early 1980's were the heyday of modern HF growth according to many sources.

Collins Radio, as well other major defense contractors such as Harris, Honeywell, Racal, etc., developed the major building blocks of communication technology that is still in use today. In many ways, the functional needs have not changed as much as the core technology has. While technology was evolving from tube-based system to the early solid state systems and then to the use of complex integrated circuits, the actual users were still using voice as the primary use and data was evolving beyond the basic Radio Teletype needs.

This site is about the technology that I was working with in this time frame. It became part of who I am today. My objective is to reach back into the past and help show the evolution forward for the new people entering the world of HF technology. There are many great sites on the Internet and the hardest challenge for a new person is to find them and relate all the various ideas into a collective and believable past.

Generally I worked with military grade "fixed" site Collins equipment and Harris equipment on a normal basis into the early 1970's. I got back involved a little when someone learned that I knew a little about the Collins 208U-10 Power Amplifier (the person wanted help was using a 208U-10 at home and had bought it new). Since then (about 1978 or so), I was starting to dream of collecting enough hardware to have a functional HF node based on the technology that I first worked with. At the same time, my interest has grown to include the use of the current modem technology to support very high data rates over the HF medium.

To be very clear, my interest is more in the application of HF technology rather than the technology itself. My "real" job is in the messaging business for wireless subscribers so there is a small connection.

Hope you enjoy the initial work so far. There is much to come. We are more or less focusing on Rockwell-Collins HF technology at the moment however we recently obtained a Harris RF-2305 receiver-exciter unit and a Harris RF-7210 ALE controller. We have five (5) Rockwell-Collins 671 series Receiver-Exciters and one 548S-5 Amplifier-Coupler. We have also obtained two Rockwell-Collins 309L2 1st Generation ALE units (if you have documentation, it would be great to see it).