Radar Sentry Alarm 3

Last month I came upon a “Vintage Radar Systems Radar Sentry Alarm Japan” on the goodwill auction site. Trying to work out what it was left more questions then answers. I’m paid in gold bars, so I spent the 14.99$ to buy the radar figuring it would be fun for Maddex and I play with in the lab. The auction ended and Michelle picked up the Radar while I was in Dublin.

Tonight the opportunity to inspect the toy finally presented itself. After going over the directions and inspecting the hardware it looks like we ended up with the manuals, keys, control station and the siren for a model SS 303 Radar.


What did I buy ?

What I ended up with is a Radar Systems Manufacturing Corp. Radar Sentry Alarm model SS-303. The SS 303 appears to come with 2 sensors and an auto dialer to notify remote monitoring. Sadly the sensors and dialer were missing from my kit. The Radar Sentry is basically a room based motion sensor. It has an advertised 36′ radius where it will detect motion and set off the siren and dialer if there is any motion.  Massive device compared to devices we have now for alarms.


Control unit and siren

According to the manual this is their “new solid state” model that replaces the tube based model before. No tube boards to play with with the kit we received. The manual hints of an option to add a tube based siren delay, but I don’t have that option in my kit. The other nice bit in the box was the keys to the case and control box, plus some swanky warning stickers.


Siren and warning Sticker

Based on the hardware we did have all we were able to test was the Siren. Which worked perfectly. For the siren alone the radar was worth the 14.99. I’m going to remove the siren from the box and mount it in the house on a ubiquiti controlled switch I can turn on and off with my phone and or with Blue Iris. It is going to be glorious. The Siren is 110 volts at 2amps according to the documentation and puts out 100DB

Lets test it in the shed with the kids! – and get it on video in case it lights on fire


Some more pictures


The kids all dressed up while we were testing the radar


The guts of the control unit


Picture in the manual explaining what it does

Leave a Reply

3 thoughts on “Radar Sentry Alarm

  • Dennis

    Started by business with Radar Sentry…….many years ago.
    Your ” Demo Kit ” brings back many memories.
    The system worked, but was not very stable. Therefore, it was a lot of work, and the future was short.
    You have a real piece of history…….

  • Bill

    Wow, what a find. The emblem of a radar sentry looks the same from the company I worked for in the mid 1970’s in Long Beach, California. The offices were originally on Cota and 16th St in West Long Beach. They moved to a larger facility just off of Magnolia and south of Pacific Coast Highway. My friend Steve and I got hired based mostly on the fact we were both Ham radio operators and thus were familiar with the electronics of the units. He got the cushy job dealing with ordering and storing the parts and I became one of the senior installers. Radar Sentry was different from anything else on the market at the time. The engineer that developed the product had been working on creating solid state power supplies for US Navy submarines. Pretty cool when you think about solid state power supplies (not batteries) back in the 1960’s and 70’s. I installed the systems for car lots, warehouses, parking lots and businesses with lots of footage to protect. Bill Williams Welding, Holmes Tuttle Ford, CBS Television City parking lot are just a few. When I left, the company was in the process of bidding on protecting the shoreline in front of the San Onofre Nuclear facility.

    For large facilities we would mount an antenna vertically on a pole and seal it in a special cone to protect it from the elements. The lines would go back to a control box that once activated would set-up a standing wave from each antenna. When someone walked into the field they would alter the capacitance and set-off the alarm or trigger a dialer. Great concept but way too many false alarms. Steve and I went back to school after four months and we never did know if they had worked out the problems. I ran across a guy I used to work with there and he said they found that by simply doubling the frequency they pretty much stopped all the false alarms. Don’t know for sure but I do know it was great for massive areas and was not bothered by inclement weather unlike many of the systems

    Your find is a product that did not exist when I worked for them. It makes sense and some good marketing on their part. Lot more consumers out there then businesses needing to protect massive areas of open space. From what you show it doesn’t look like the concept changed much. A control box and antennas to propagate the standing waves.

    To close the circle Steve went on to be a senior technical writer for Boeing in Seattle and I retired as a senior IT engineer in charge of a major west coast city Internet and Intranet. We both thought working at Radar Sentry introduced us a facet of electrical engineering that had never occurred to either of us. Thanks for sharing your find and good luck with it.