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Old 28th May 2020, 6:06 pm   #1
ColinTheAmpMan1
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Default Clarostat power decade box 240-C (or similar).

Hi,
Does anyone have one of these power decade boxes that they would be prepared to sell? I missed out on buying one for about 200 a while ago. The prices that you see them going for in the USA are quite high, but putting the shipping cost to the UK on top makes it a bit of a non-starter. They have high-power glass resistors and of course all of these would need to be intact. Collection is a possibility within the London area, but I think Lands End and anywhere in Scotland would necessitate courier (hopefully not too expensive).
TIA, Colin.
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Old 31st May 2020, 2:21 pm   #2
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Default Re: Clarostat power decade box 240-C (or similar).

I had a feeling that this was a forlorn hope.
Colin.
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Old 31st May 2020, 2:37 pm   #3
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Default Re: Clarostat power decade box 240-C (or similar).

Give it a chance, it takes quite a while for all members to see a post. Some log on infrequently.
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Old 31st May 2020, 3:07 pm   #4
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Default Re: Clarostat power decade box 240-C (or similar).

How much power is power?

Most boxes seem to top out at about 1A on the 1 ohm range. After that you need a load bank.
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Old 31st May 2020, 7:34 pm   #5
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Default Re: Clarostat power decade box 240-C (or similar).

Quote:
Originally Posted by woodchips View Post
How much power is power?

Most boxes seem to top out at about 1A on the 1 ohm range. After that you need a load bank.
Yes, that's what makes the Clarostat what it is. If you check the spec, you will find it is 225W or 1000VDC/660VAC per decade. Just the job for testing power-supplies and more convenient than a string of power resistors. The range is 1 ohm to 999.999 ohms in six decades, though the pictures show confusing numbers on the decades; possibly there is a decimal point that I can't see clearly.

AC/HL, perhaps I sounded too negative, I will still wait, but to be honest with you the thread needed a bit of a bump, as it had sunk onto the next page, where it would be seen less and by fewer.

Colin.
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Old 31st May 2020, 7:36 pm   #6
factory
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Default Re: Clarostat power decade box 240-C (or similar).

Is one at 210 including shipping & custom fees from the US to much?
https://www.ebay.co.uk/itm/324175990535

Max ratings for each decade, from here; http://userequip.com/files/specs/397...nstruction.pdf

X1 = 5A
X10 = 1.5A
X100 = 0.5A
X1K = 150mA
X10K = 50mA
X100K = 5mA

Interesting they only use five resistors for each decade, switched by a three layer wafer switch & lots of wiring.

David
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Old 31st May 2020, 7:42 pm   #7
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Default Re: Clarostat power decade box 240-C (or similar).

Quote:
Originally Posted by ColinTheAmpMan1 View Post
Quote:
Originally Posted by woodchips View Post
How much power is power?

Most boxes seem to top out at about 1A on the 1 ohm range. After that you need a load bank.
Yes, that's what makes the Clarostat what it is. If you check the spec, you will find it is 225W or 1000VDC/660VAC per decade.

Colin.
I think there is a typo somewhere, it looks more like 225W max for the whole unit, it's replacement (IET HPRS) is 250W for the whole unit, or maybe I'm wrong but 1350W total seems excessive.

David

Last edited by factory; 31st May 2020 at 7:55 pm.
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Old 1st Jun 2020, 9:32 am   #8
ColinTheAmpMan1
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Default Re: Clarostat power decade box 240-C (or similar).

Quote:
Originally Posted by factory View Post
Quote:
Originally Posted by ColinTheAmpMan1 View Post
Quote:
Originally Posted by woodchips View Post
How much power is power?

Most boxes seem to top out at about 1A on the 1 ohm range. After that you need a load bank.
Yes, that's what makes the Clarostat what it is. If you check the spec, you will find it is 225W or 1000VDC/660VAC per decade.

Colin.
I think there is a typo somewhere, it looks more like 225W max for the whole unit, it's replacement (IET HPRS) is 250W for the whole unit, or maybe I'm wrong but 1350W total seems excessive.

David
You are, of course, quite right. It is a matter of how you read the spec. Perhaps I should have made it clearer that the 225W was for the whole unit, not for each decade, but I was quoting from the maker's figures.

The item on eBay that you refer to might just be worth considering, but it has to be said that shipping charges and import duty nearly double the asking price.

Colin.
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Old 1st Jun 2020, 1:08 pm   #9
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Default Re: Clarostat power decade box 240-C (or similar).

Maybe a regular search for Clarostat decade box 240, 250 (rack version) and Winslow decade box 336 (same thing rebranded) on both ebay.co.uk & ebay.com will help as they can go for less.

If my maths is right this is the lowest buy-it-now (just under 200 with shipping & fees) at the moment; https://www.ebay.co.uk/itm/202989201091
There is another on auction but I'm not sure we are allowed to give a link to auctions.

I'm not sure what the UK equivalent would be, the Time 1065 is much lower rated & doesn't go as high in resistance, I used one at work occasionally for resistor substitution, but we used those big sliding variable resistances for load tests, or heat-sinks covered in those metal clad power resistors.

David

Last edited by factory; 1st Jun 2020 at 1:18 pm.
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Old 16th Jun 2020, 3:37 pm   #10
ColinTheAmpMan1
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Default Re: Clarostat power decade box 240-C (or similar).

One of these that I saw on eBay turned up on my doorstep yesterday. I was offered a reduction and so the total price, including shipping, was a bit less than 200. It seems rather nice and smaller than I thought it would be.
My next task is to try to access the switches, etc., to see if a bit of cleaning would be advantageous.
Since I now have one of these, the thread can be closed, please.
Colin.
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