# oscilloscope CRT PM's



## Geo (Mar 23, 2012)

i have a couple dozen oscilloscope test fixtures to scrap. after accidentally breaking one of the CRT's from a scope, i could see the internal make up. it was porcelain with a gold coating on the inside.

there were some that was silvered, and when tested, showed positive for silver. but then, i found three with a dull grey metal coating. testing with gold and silver test solution showed no reaction, but one drop of Pt test solution showed an almost immediate response.

so to be sure, i added another small drop on a spot that i had cleaned well.


so, is this metal platinum?


----------



## goldsilverpro (Mar 23, 2012)

Are they Tektronix o'scopes? In the 70s, A friend of mine was getting 30,000# of in house scrap from Tek each month on a recovery basis - same looking stuff - gold lined ceramic CRTs, mostly in pieces. He was stripping it in a fairly large mixer with cyanide. There was no Pt on that stuff but it was 35 years ago. I would scrap or sand some off into a spot plate, add a few drops of AR (might need to heat the spot plate a bit), and test with stannous chloride, as per Hoke.


----------



## samuel-a (Mar 23, 2012)

Man... i wish i had investigated deeper into the inner coating when i had the chance...
I even remember GSP shared the exact same info back then.

 

Great find Geo. Let us know more if you process them for gold.


----------



## solar_plasma (Oct 29, 2013)

Old oscillloscopes seem to be cheap on ebay. What is the estimated thickness of the gold plating inside the tube?


----------



## rickbb (Oct 29, 2013)

Don't CRT's have some mercury in them as well?


----------



## resabed01 (Oct 29, 2013)

rickbb said:


> Don't CRT's have some mercury in them as well?



No, they shouldn't. The glass may contain lead.


----------



## Geo (Oct 29, 2013)

unsure of the thickness. since it is for RF shielding, its not that great.its the overall area that makes the recoverable gold worth the effort. the gold was very simple to recover with hcl/Cl. the grey metal was Palladium as it turned out. the electronics were the real find in these. each unit came with its own roll of silver solder and all the connecting bridges had thick silver. there were several dozen thyristor and transistors that had nice thick gold plating.


----------



## CBentre (Oct 29, 2013)

rickbb said:


> Don't CRT's have some mercury in them as well?



Rick,
CRT's don't but LCDs usually contain small amounts of mercury in the back lights. I think this is where the confusion is when people mention mercury in displays.


----------



## Anonymous (Oct 30, 2013)

CBentre said:


> rickbb said:
> 
> 
> > Don't CRT's have some mercury in them as well?
> ...



100% correct Sir.

This is why LCD disposal is becoming more of a headache than CRT disposal ever was.


----------



## pgms4me (Oct 30, 2013)

I have been scrapping the old tektronix scopes for years. never knew the ceramic lined crt's had any pm's until I read an old thread on here . I have since been saving the crt's. The ones that I have are ceramic on the outside, but the neck where the pins are is still glass. Does the ceramic change to glass or is it fused somehow?.I have yet to open one up. Also does anyone know if the cathode or grid elements contain any values? If someone has the Tektronix model numbers of the scopes that have ceramic tubes ,That would be very helpful. thanks for starting this thread.


----------



## Geo (Oct 30, 2013)

all of the scopes i scrapped had glass where the pins connect and of coarse the screen is glass. it looks to be thermally fused to the ceramic body.


----------



## etack (Oct 31, 2013)

pgms4me said:


> I have been scrapping the old tektronix scopes for years. never knew the ceramic lined crt's had any pm's until I read an old thread on here . I have since been saving the crt's. The ones that I have are ceramic on the outside, but the neck where the pins are is still glass. Does the ceramic change to glass or is it fused somehow?.I have yet to open one up. Also does anyone know if the cathode or grid elements contain any values? If someone has the Tektronix model numbers of the scopes that have ceramic tubes ,That would be very helpful. thanks for starting this thread.



The grid will be a low thermal expansion alloy I believe they are Invar. If you had over 500# it is worth saving smaller amounts not really able to get the attention of real buyers. The scrap yard may pay something for it.

Eric


----------



## solar_plasma (Apr 28, 2014)

Would you guess it to be about 2 µm thickness or even more?


----------



## Geo (Apr 28, 2014)

I would be afraid to try and guess and I have no real knowledge of PM content other than the twenty (some larger and some smaller) or so that had gold yielded a little less than 5g. Someone with more technical knowledge may have a better answer.


----------



## gallium guy (Jun 21, 2014)

I ran a test on exactly one crt from one of those and got .4 grams out of it. Not too shabby for something most folks will not even take. I got about ten in an old surplus pile. :!:


----------



## tedpgh (Jun 25, 2014)

Etack mentions Invar which is a nickel alloy, I'm attaching a photo of an element (aka "ray gun"?) that is definitely not Invar... 

I was curious if anyone knew of what the material might be? Otherwise I'll shelve it until I'm finished moving my lab.

Regarding CRTs, I know those of televisions and monitors have lead in part of the glass - I believe the shell. In the past, that glass was recycled to make more CRT tubes. Today, it's a problem because we don't have a large-scale use for the glass and lead removal is difficult.

-Ted


----------



## necromancer (Jun 25, 2014)

tedpgh said:


> Regarding CRTs, I know those of televisions and monitors have lead in part of the glass - I believe the shell. In the past, that glass was recycled to make more CRT tubes. Today, it's a problem because we don't have a large-scale use for the glass and lead removal is difficult.
> 
> -Ted



yes, the front part of the crt tube is leaded glass


----------



## solar_plasma (Jun 25, 2014)

I don't know the composition, but maybe someone who has the technology and skills to make lead crystal wine glasses of this material, would benefit from it. :lol: At least if those two materials should have the same composition.


----------



## necromancer (Jun 25, 2014)

here is one thing that is made from front panel crt screens

http://www.flowcrete.co.uk/our-products/isocrete-floor-screeds/


----------



## tedpgh (Jun 25, 2014)

For clarity, I should point out I mentioned lead content after someone inquired about mercury.

There is a developing process that appears cost-effective for the separation of lead from the glass. I mention all of this because, it was once relatively lucrative to recycle the glass - not so much in recent years. 

If you are after PM's from various sources and you can start dealing in quantity it's important to know where you can reduce waste stream or altogether eliminate it and get paid. The direct benefit to us, is we cut disposal cost and capture more income. We also keep more useful materials circulating in our economy and reduce environmental impacts. 

All that said, anyone have input on the makeup of the element I posted?

-Ted


----------



## necromancer (Jun 25, 2014)

tedpgh said:


> For clarity, I should point out I mentioned lead content after someone inquired about mercury.
> 
> There is a developing process that appears cost-effective for the separation of lead from the glass. I mention all of this because, it was once relatively lucrative to recycle the glass - not so much in recent years.
> 
> ...



do you have any part numbers for this part ?


----------

