We always ran a small amount of DowTherm in our MSDC klystrons with no
resistance issues. ( only 24KV ).
Don W4DNR
Quoting "Roger (K8RI)" <k8ri@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@rogerhalstead.com>
To: amps@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@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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