What is an Intervox? Can I use it to take over the world?
May 28, 2009 8:30 PM   Subscribe

What is this crazy sci-fi looking device I bought at a salvage store? It has knobs, a compass, and a bizarre spinning top.

I purchased The Device at a construction salvage store in Seattle today. The top part rotates, and the base has the compass points on it. The dial reads "275 ... 300 ... 325", and the two knobs at the bottom are marked "L" and "P". It's got vacuum tubes inside!

No one at the salvage place knew what it was either, and they made me promise to call back if I found out.

posted by agropyron to Technology (9 answers total) 3 users marked this as a favorite
Best answer: Radio direction finder I believe. Used for...marine navigation in teh days before GPS and LORAN?
posted by gofargogo at 8:42 PM on May 28, 2009

I believe gofargogo has it. This looks like the same or similar model on ebay.
posted by exogenous at 8:51 PM on May 28, 2009

Response by poster: Awesome! Thanks gofargogo and exogenous. I wonder what the one on ebay will sell for, it looks like it might still be functional.
posted by agropyron at 8:56 PM on May 28, 2009

Cool find! It was manufactured locally, possibly in the early '50s.

Intervox Corp. manufactured ship-to-ship telemetry and ultra sonic underwater systems. Honeywell acquired the company in 1951 and, at some point, moved it under Honeywell’s Marine Equipment Division (MED), which formed a deep ocean research unit designed to study ocean mechanics, acoustics, magnetics, and thermodynamics.

The same unit--or one like it--might be referenced in this account from one of Seattle's old school Norwegian fishermen:
"When I started, I started in 1948 -- no, ’48? No, ’46. I graduated from high school in ’46. Then all -- then we had a Fathometer, an old surplus Fathometer. And then he also -- the boat I was on had a direction finder, an old Intervox direction finder that they used to find the outlaw radios during the war. They had earphones on and a big dry cell battery. And that’s what we used to navigate to get the light ship -- lighthouses and the signals like that."
posted by prinado at 9:09 PM on May 28, 2009

You can see similar equipment in use in films such as The Heroes of Telemark, where Norwegian Nazis are attempting to locate partisans communicating with British intelligence.
posted by dhartung at 9:34 PM on May 28, 2009

I crossed the English Channel in dense fog in a small boat once using one of these devices, very similar to the Allan Marine handheld unit from gofargogo's link, above. It worked remarkably well, considering I was at the time used to Loran.

The way that unit worked was it had a little spyhole in it, you held it up and pointed it in the approximate direction you wanted to go (you had to know this, but really that isn't asking too much, one hopes). You small backlit needle could then be centred, when it was then you depressed a button and it locked the compass on top,. You could then read off the compass bearing to the radio tower.. Repeating this on another radio tower allowed you to triangulate onto a chart (which had the radio towed marked on) and hence set a course. I was surprised that these towers were still maintained but I suppose at that time it was just a few years before the widespread advent of GPS and Loran was quite expensive for smaller boats.

This basic technology was also instrumental in guiding British bombers to their targets in WWII.
posted by Rumple at 10:29 PM on May 28, 2009

I meant to say, we ended up coming out of the fog within 1000 yards of where we thought we were after being in fog for over 12 hours - this was Southampton to Cherbourg in a 24 foot sailboat.
posted by Rumple at 10:30 PM on May 28, 2009

Judging from the view inside, I'd estimate a vintage of 1930s. It doesn't have the markings of military gear, so it's a commercial model. It does look a lot like the eBay unit that sold for $54, but yours is more weather-beaten. So, I guess worth less to a collector, but definitely more artistic for your mantel. :-)
posted by exphysicist345 at 10:40 PM on May 28, 2009

Radio direction finding was the first electronic means for ships to find their way when they couldn't see shore (e.g., foggy).

The two circles on top are antennas that you rotate to find the maximum or minimum signal from a known radio station. You note the direction in degrees from the dial at the base of the circles and plot that on your chart. Do it again for another known radio station and you know where your ship is on the chart.
posted by exphysicist345 at 10:47 PM on May 28, 2009

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