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Old 21st Jun 2021, 8:46 pm   #1
Courtney Louise
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Default Mercury Arc Rectifier

Hey all

I know there are some people out there as nuts as I am so it goes to figure that someone out there probably has a spare MAR.

I want to make a display one like they used to have in the Museum of Science and Industry in Birmingham.

Does anyone have a spare please?

Kindest

C
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Old 21st Jun 2021, 9:15 pm   #2
The Philpott
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Default Re: Mercury Arc Rectifier

I know someone who has one or more that have 'gone to air' and won't therefore work. He may or may not want to part with one, but i will ask. It might not be an immediate answer as last time i contacted him he was very busy. Also he's down south which could be a problem for you.

Dave
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Old 22nd Jun 2021, 5:02 am   #3
Diabolical Artificer
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Default Re: Mercury Arc Rectifier

There used to be a bloke on Ebay sold em in Derby, doesn't seem to be the case anymore. Don't have an MAR but have a couple of big MVR I might part with Courtney, problem is they take oodles of power to light and need a heavy current (+ load), something like 1kvA @ 1A to get a good glow out of em; not a simple proposition to power,lethal in a pub/club.

Andy.
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Old 22nd Jun 2021, 7:04 am   #4
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Default Re: Mercury Arc Rectifier

You have to be careful with these things they can give off UV and x ray radiation The ones I used to work with were behind very thick dark glass screens
We used them down the pit for charging the very large battery locomotives
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Old 22nd Jun 2021, 7:28 am   #5
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Default Re: Mercury Arc Rectifier

Quote:
they can give off UV and x ray radiation
The UV is absorbed by the glass and you need at least a few kV for x-rays.
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Old 22nd Jun 2021, 10:01 am   #6
Andrew Humphriss
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Default Re: Mercury Arc Rectifier

Hello not sure if this is the correct area to ask a question?
I have purchased a few hallicrafter receivers through E-Bay the last one a Continental bakelite green am short wave radio has been restricted when I complained to E-Bay they said the valves may contain mercury vapour?
Can any one explain this one
Thank you
Andy 2E0NDZ
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Old 22nd Jun 2021, 10:11 am   #7
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Default Re: Mercury Arc Rectifier

There are more normal rectifiers that contain tiny quantities of mercury. The Mullard Master Test Board uses one for example (AX1). They are quite rare though and very temperamental. I am very surprised that a Hallicrafters set used one but it is not totally impossible.

But these valves are quite rare and unlike mercury arc rectifiers which are high power industrial jobs.
Unlike the arc rectifier, the quantities of mercury in other valves will be more like the very common "valve" namely the fluorescent tube light!
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Old 22nd Jun 2021, 12:18 pm   #8
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Default Re: Mercury Arc Rectifier

It's not unknown for carriers etc. to assume that as valves have a silvered appearance they contain mercury.

There are anecdotal stories that carriers have refused to transport such items and the sets concerned have later appeared on eBay minus their valves.
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Old 22nd Jun 2021, 12:48 pm   #9
The Philpott
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Default Re: Mercury Arc Rectifier

-To get Hg/METALLIC mercury hazard into context, it took a whole box (probably approaching 30) of smashed 8' fluorescent tubes to cause mercury poisoning in two small children- and this was because they found very many globs of mercury on the paved floor of the greenhouse in which they were kept (the tubes, not the children) and played with them for an extended period. Persuading an auction/buying/selling website of the negligible hazard of a little valve will be quite another matter. MAR's containing several kilos of Hg have been sold through normal channels online before without a hitch, possibly because algorithms applied to listings get confused by the manufacturer of marine engines and electrics 'Mercury' who sell solid state rectifiers online! (Also MAR's tend to be 'collect only' so courier issues do not arise as such)

Mercury compounds (organic or inorganic) are of course another matter.

Moderators,I am only harping on about this as it may assist the query by Andrew in dealing with the vendor/vendor's agent, i don't wish to spark a hazard debate. If it's a customs issue he's probably out of luck anyway.

Back on original topic, as i understand it the guy in Derby (if indeed we refer to the same seller) got a whole batch of MAR's but it was, i think, a one off loft clearance.

Dave
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Old 22nd Jun 2021, 5:51 pm   #10
Keith956
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Default Re: Mercury Arc Rectifier

Anyone who has old style fillings has a few grams of mercury in their mouth...
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Old 22nd Jun 2021, 11:54 pm   #11
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Default Re: Mercury Arc Rectifier

Recently I've seen a few similar complaints about mercury and 'restricted item' on the US vintage radio forum, it was a bit of a surprise as earlier this year I sold my stock of 83 rectifiers one at a time, stating in the ad that they contained mercury vapour and gave out a blue glow under operation, nothing was flagged as restricted - I double boxed as I always do and posted them at the local post office, all of the sales went off with out a hitch.
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Old 23rd Jun 2021, 5:33 am   #12
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Default Re: Mercury Arc Rectifier

Mercury eats its way through aluminium. Aeroplanes are made of aluminium, and much mail and small parcel traffic goes by air. So transport companies are seriously worried by the prospect of mercury on the loose. It doesn't take much of it to write a plane off and the discovery of any will initiate a costly cleanup and inspection process before the plane can fly again. Think of the prices of Boeing 737s and larger.

Anything containing mercury is treated as hazardous goods. Mercury vapour tubes at ambient temperature have their mercury condensed into liquid droplets. The amount in an MAR would be very destructive.

The reason for the restricted item status isn't itself in the remit of the forum, but it has an effect on the shipping of several of our sorts of things.

There are phrases in the fine print of post offices and couriers so that if you cheat, you can be held liable for any consequences.

David
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Old 23rd Jun 2021, 6:45 am   #13
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Default Re: Mercury Arc Rectifier

I sold my sextopus years ago - it had been haunting the garage until then and I was always worried what I'd do if it fell off the rack!

You might also try recyclers - there is a firm (forgot the name) in or near Salford that gave me several large mercury vapour (not arc) rectifiers some years ago, I guess cheaper for them to give me them than process them. Probably a slim chance but may be worth a try.
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Old 24th Jun 2021, 9:10 pm   #14
The Philpott
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Default Re: Mercury Arc Rectifier

Meanwhile, enthusiasts might want to view photonicinduction's latest youtube video, one of the better clips of operation available. The boxed 'tube he bought recently looks, underneath all the dust, to be unused. Very jammy!

Dave
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Old 25th Jun 2021, 11:34 am   #15
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Default Re: Mercury Arc Rectifier

Hi this guy has lots https://www.youtube.com/watch?v=2pDcv6g1FE0 Mick
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Old 26th Jun 2021, 9:00 am   #16
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Default Re: Mercury Arc Rectifier

Good luck with your search, hope you find one!

This is my current screen lock on my phone...
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Old 26th Jun 2021, 11:37 am   #17
The Philpott
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Default Re: Mercury Arc Rectifier

That's the guy, Mick. It's a shame that he found that most of the units he acquired can't be made to work (air ingress possibly) but he did at least get this one for a reasonable price!
Dave
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Old 26th Jun 2021, 12:06 pm   #18
merlinmaxwell
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Default Re: Mercury Arc Rectifier

I have just got back from Kempton Steam Museum, they have two MARs running and I tried out my LCD shutter to see if it make the arc rotate slowly, it did. It uses one of these https://shop.pimoroni.com/products/l...nt=47109536138 and an 8 pin micro to slowly modulate twixt 48 and 52Hz. The camera I tried to record it on failed miserably (too clever by half). I gave it to the museum and I think they will install it, so you will have to go there to see it.
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