[Amps] water purity/conductivity in water cooled tube amplifiers

[donroden at hiwaay.net]

We always ran a small amount of DowTherm in our MSDC klystrons with no  
resistance issues.  ( only 24KV ).
Don W4DNR


Quoting "Roger (K8RI)" <k8ri at rogerhalstead.com>:

> The system I worked on was installed around 1960 and AFAIK it came  
> out of service around 2000 - 2010. As for the copper oxide, the   
> foot and a half to two foot long anodes of the tubes  in the 200+ KW  
> generators looked like they'd been stuck in a sewer.  That deposit  
> sure didn't look like what it really was :-D Back in those days  
> changing the water was pretty much our only known option.
>
> Just from the size of the pump, I think John's system was far larger  
> than ours.
>
> 73, Roger (K8RI)
>
> On 4/28/2018 1:37 PM, John Lyles wrote:
>> I concur with Roger, and have always been taught to avoid using  
>> Brass fittings in a high resistivity pure water system for  
>> amplifiers. Zinc leaches out, but then again, I don't have systems  
>> with routine water replacement, as we use Cuno or Culligan 'resin'  
>> beds and oxygen removal bottles in a continuous purification loop.  
>> It is done in a sidestream running a few GPM through these bottles,  
>> and they are replaced about annually. The main DI system has 100 hp  
>> pump and is 950 GPM.
>>
>> In another building where I have a test amplifier and dummy loads,  
>> the water does need replacement every 5 years or so, even with the  
>> purification loop. Somewhere in the myrad of pipework, there are  
>> some bad materials that will, over time, deposit copper oxide and  
>> other coatings inside of hoses and anodes of tubes.
>>
>> John
>> K5PRO
>>
>>
>>
>>> Date: Tue, 24 Apr 2018 11:21:01 -0400
>>> From: "Roger (K8RI)" <k8ri at rogerhalstead.com>
>>> To: amps at contesting.com
>>> Subject: Re: [Amps] water purity/conductivity in water cooled, tube, >
>>>     amplifiers
>>> We use what we have, what we can afford, and / or what's available.?
>>> That said, brass is one of the poorest metals to use with DI, or
>>> distilled water.
>>> BUT On the positive side, even with monster QRO amps, their runs are of
>>> a relatively short duration.? I've seen around 30, 12KW RF generators?
>>> that have shared cooling water running through them 24 X 7.? There was
>>> the occasional down time for various reasons, but the resistivity was
>>> only checked on a weekly basis.? 24 X 7 That's 168 hours each per week,
>>> but with 30 that cooling system was receiving 5,040 hours per week.? If
>>> the water is changed every 20 weeks, that is roughly 100,800 hours per
>>> water change.? As I remember the water tank was somewhere between 500
>>> and 1000 gallons
>>> "IF" the amp has only a couple gallons capacity and it runs, say 25
>>> hours per week, experience tells me that unless there is something
>>> unusual about the system, "I would expect" the need to change the water
>>> as once or twice a year. It might go several years.
>>>
>>> 73 and good luck,
>>> Roger (K8RI)
>>>
>>>
>>> On 4/23/2018 11:33 PM, Randy wrote:
>>>> On 4/23/2018 9:28 AM, amps-request at contesting.com wrote:
>>>>> ----------------------------------------------------------------------
>>>>> I know that really pure water is actually corrosive and will do it's
>>>>> best to gain ions in order to get to some natural level of
>>>>> minerals/contaminants.??? I built the coolers out of several pieces of
>>>>> brass and hard silver brazed it all together.? I know the electrical
>>>>> current will cause an etching or eroding effect of the materials in the
>>>>> cooler, but I used what I had.?? At this point, I have no idea how often
>>>>> I will changing? out the water.? Could be after only 10 hours of use, or
>>>>> it may be 100 hours and the cooler may rot out in no time.
>>
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>
> -- 
> Roger (K8RI)
>
>
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