# Anyone familiar with Farran radar products?



## darshevo (May 9, 2011)

This came out of a device that was apparently in use at the airport at one time. Not a lot of information on Farran's website about it and I had no luck digging up a retail value. It looks to me to be gold plated (I was sure it was when I got the device). Seems unlikely for it to be fully plated inside and out though. I did take the grinder to a corner and it's aluminum so I know I am not mistaking brass for gold plating. 

I took an eraser to it as I have seen mentioned in other threads and after a good rubbing it polished right back out leaving a rub mark, but not through to the base metal. 

Here is the link to Farran's website: http://www.farran.com/index.php?option=com_content&task=view&id=101&Itemid=172

Assuming this is actually gold plated any idea on how many microns thick it might be? 

Here are pics of both sides:







As always, thanks for taking the time to look and for your comments

-Lance


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## patnor1011 (May 10, 2011)

Are you sure it is not just anodized aluminum? You can scratch small bit dissolve in acid and test with stannous.


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## Harold_V (May 10, 2011)

It looks like gold from the picture. Note the deep reflective color in the counterbored holes of the cover. You don't get that from anodizing. 

There was a point in time when plating on some items was absurdly thick. I processed some early microwave components (military) that yielded gold in keeping with that of filled gold objects. It's rare as hens teeth, but it does (or did) exist. 

Harold


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## Militoy (May 10, 2011)

Gold over copper or copper + nickel on aluminum wouldn't be unusual in a waveguide and plenum shield assembly like the one in the photos. The nesting of the grooves, and the precision fit of the gold contact areas prevent RF leakage without the need for less-effective RF gasketing. It's possible it could be Class 3 chem film - but I'm going with Harold's assessment - I'd bet on gold.


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## darshevo (May 10, 2011)

When I bought Lasersteves videos I picked up some tin as well so I could put some stannous together when the time came (so far I am only collecting material). What would be the best method to dissolve the test sample in? Can I use AP, or will that not work with an aluminum base metal? I tried search, but like a lot of people without hands on experience I was quickly overwhelmed by the number of responses. What about hcl-cl? I know it is not used as a method to remove gold from a base metal as it will drag other stuff into solution that would be better dissolved prior to the gold, but for a stannous test?

I have hcl and sulfuric (new, clean battery acid) on hand as well as the usual household chemical like H2O2 and Clorox.


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## lazersteve (May 10, 2011)

If the base metal is Aluminum it will dissolve in HCl.

If it is copper use AP.

Steve


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## Oz (May 12, 2011)

Steve is dead on, but I would like to add that you need to keep it away from open flame as it produces copious quantities of hydrogen gas.


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## hds (May 24, 2011)

I work in the aerospace and defense industry, gold plating is quite common... if it's aerospace and it looks like gold, it probably is =P

It's easier to find gold and precious metals in "flying" devices than in ground-based devices though, but radar and microwave systems in general often have heavy plated shielding parts, and many times the chips themselves are gold-shielded or have gold plated protective shields


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## g_axelsson (Jan 5, 2014)

Militoy said:


> Gold over copper or copper + nickel on aluminum wouldn't be unusual in a waveguide and plenum shield assembly like the one in the photos.





darshevo said:


> What would be the best method to dissolve the test sample in? Can I use AP, or will that not work with an aluminum base metal?



It's an old thread but I just wanted to add my comments.

Darshevo, I know you didn't list nitric acid as one of the chemicals you have but for anyone else reading this thread I would recommend nitric acid. It would attack only the thin copper or copper + nickel layer between the gold and the aluminum. There is no need to dissolve all the massive base metal. This worked just fine on gold plated aluminum the one time I have tested it.

Gold is common in microwave equipment. The high frequency forces the microwave signal to move only in the top layer of the metal (skin effect), any oxidation in the surface is affecting the resistance of the wave guide and can easily affect the signal integrity. That is why you rarely find bare copper in wave guides. It usually is silver or gold plated.

Generally, you don't have any anodized aluminum in any parts that relies on good conductance. The anodized surface is converted to Al2O3 (aluminum oxide, sapphire) which is an insulator.

Göran


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