Interesting Repair of the Day: Raytheon R20 – vintage 1988!

There’s an old Star Trek episode  – “The city at the edge of forever” where Kirk and Spock end up going back in time to the 1930’s. In their attempt to get back to their own time, Spock tries to repair his damaged  Tricorder using the  available materials of the day – tubes and such.  Kirk’s 1930’s girlfriend discovers Spock’s efforts, and when asked what he was up to, he  responded brilliantly:

I am endeavoring, ma’am, to construct a mnemonic memory circuit using stone knives and bearskins.”

I have unashamedly borrowed that expression “Stone Knives and Bear Skins” and use it regularly to describe “vintage” equipment.


Case in point: The 1988 Raytheon R20 radar display that came in the other day.




I’ve worked on a LOT of R20’s over the years, and really thought I had seen the last of these beasts. 27+ years is an AWFULLY long time in the world of marine electronics.

I started my career in this business in the early 80’s when this units predecessors – the Raytheon 1200 & 2500 were considered “state of the art” and indeed they were. This baby came out a few years later and it was quite a jump in performance.  Frankly, its target detection capability would compare favorably against a modern radar of similar class – assuming it is well calibrated and the magnetron still has good output.

The customer explained his situation and having been down this road many times, I knew immediately what the problem was: a corroded keyboard.  He then explained that water damage was unlikely, because the display was mounted below decks at the Nav station – and did not get wet.

OK – we’ll see.

Once on the bench, I started turning screws and removed the keyboard. Sure enough: Water damage.


New and old.  Click on the photo for a better view.

Lucky for him, I had one in my Raytheon parts bin – collecting dust under the bench and waiting for just this sort of occasion.



This old girl should be going home soon, and may last another 27 years.

Stone knives and bear skins, indeed!






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