What IS this thing??

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What IS this thing??

Postby zebrostripe » Mon Nov 01, 2010 6:07 pm

I got this in a batch of stuff I acquired and I cannot find any information on it. It has a date on the badge "6-22-39". Its called an "Impedance Measuring Unit" type number "CA323". It came with the original instruction book for it too! I'm just curious if there's anyone out there who's seen something like this and perhaps would have any more information on it.

http://s1135.photobucket.com/albums/m632/zebrostripe/Impedance%20Measuring%20Unit%20CA323/

Thanks for looking.

-z
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Postby TomMcNally » Mon Nov 01, 2010 8:07 pm

That's a piece of test equipment commonly called an "impedance bridge" for a frequency band of 200 to 500 kHz. That's low frequency, below the
AM Broadcast Band which starts at 540 kHz. That band is used for
Airport NDB (Non Directional Beacon) transmitters, which basically
send out slow speed Morse code with the airport Identifier.

That unit would be used to help tune antennas, and at the low
frequency they would be really long wires.

Unfortunately, it's not useful for anything in the modern world.
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Postby zebrostripe » Mon Nov 01, 2010 10:21 pm

Thanks! I really appreciate the info! I guess I'll just put it up on my shelf of useless but interesting stuff.
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Postby Geek » Tue Nov 02, 2010 3:30 am

TomMcNally wrote:Unfortunately, it's not useful for anything in the modern world.


AHEM!

Google LowFER or checkout the LWCA.org - lotsa uses still for us RF expreimenters ;)

Cheers!
-= Gregg =-
Fine wine comes in glass bottles, not plastic sacks. Therefore the finer electrons are also found in glass bottles.
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Postby TomMcNally » Tue Nov 02, 2010 7:56 am

Make him an offer! $)
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Postby zebrostripe » Tue Nov 02, 2010 8:28 am

Thanks for the additional links/info. Looks like some real interesting reading. I've got no idea of the actual worth of this thing, but I'm not opposed to letting it go for a reasonable price to someone who'd find a use for it. : )
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Re: What IS this thing??

Postby ChrisAlbertson » Tue Nov 09, 2010 4:27 pm

zebrostripe wrote:I got this in a batch of stuff I acquired and I cannot find any information on it. It has a date on the badge "6-22-39". Its called an "Impedance Measuring Unit" type number "CA323". It came with the original instruction book for it too! I'm just curious if there's anyone out there who's seen something like this and perhaps would have any more information on it.

http://s1135.photobucket.com/albums/m632/zebrostripe/Impedance%20Measuring%20Unit%20CA323/

Thanks for looking.

-z


What you have is a 1930's vintage Impedance bridge. It would be good for measuring inductors or capacitors and I bet is accurate to about 1%. It think it is also suitable for more advanced work such as measuring complex impedance of networks, cables and antenna.

The way they work is to place an AC voltage accros the unknown device and then you do the same with a calibrated variable device and adjust the variable one until it matches the unknown one.
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Postby zebrostripe » Thu Nov 11, 2010 7:28 pm

Thanks! I'm hoping to do a little experimenting with it soon and if it measures caps like you say it does, then it could become a most useful tool. I appreciate the enightenment!
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