Jim,
It Sounds like you have a pretty good handle on Cooling your MOSFETS!
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________________________________
From: Amps <amps-bounces@contesting.com> on behalf of Joe Subich, W4TV
<lists@subich.com>
Sent: Tuesday, October 8, 2019 12:01
To: amps@contesting.com
Subject: Re: [Amps] Coolant for liquid-cooled solid-state amp
With cooling systems like the MOSFETs (tubes in a copper spreader)
electrical conductivity isn't a problem.
Unless your radiator is outside and the plumbing is exposed to freezing
temperatures, straight distilled water is your best bet. Plain water
has better thermal transfer characteristics than the glycol/water mix.
As long as you are using nonconductive plumbing (rubber/plastic) hose
to connect the thermal "plate" to the radiator and pump, there should
be little or no electrolysis even if one is using a copper thermal plate
and aluminum radiator or cast pump.
If the radiator (and/or sump) is outside and exposed to freezing temps,
by all means use 50% water and 50% ethylene glycol.
Other than in the south - particularly where the transmitters were run
24/7 - every water cooled broadcast transmitter I've ever seen (and I
installed, operated, serviced and/or consulted on a substantial number
of transmitters/sites over the years) uses 50/50 distilled water/glycol.
In fact, the only transmitter that did not use glycol did after I fixed
the cooling system <Doh>!
73,
... Joe, W4TV
On 2019-10-08 1:26 PM, Jim Barber wrote:
> Hi Bob, thanks for the reply.
>
> In this particular case, the electrical conductivity of the coolant doesn't
> matter as long as the cooling efficiency stays up and
> the corrosion doesn't become an issue for the radiator, the baffle block or
> the pump. (I assume you meant electrical conductivity, not thermal)
> Would that change the equation?
>
> Anything that contributes to the conversation and gets people thinking
> contributes to the SNR... I'm no expert when
> it comes to these kinds of cooling systems, so can use all the help I can
> get.
>
> Thanks!
> Jim N7CXI
>
>
> On Tue, Oct 8, 2019 at 9:58 AM Bob Darlington <rdarlington@gmail.com> wrote:
>
>> Jim,
>>
>> Plain ol' distilled water will remove heat a lot better than diluting it
>> with glycol, however the chemistry may dictate using it. Deionized water
>> is much more corrosive than distilled even if it starts life as a very poor
>> conductor, but will quickly leech metal ions into the solution (although
>> not much volume!) and will likely become more conductive faster than
>> starting with plain distilled, but it might be a photo finish as to which
>> needs to get replaced first. Just an FYI, and I hope this has a slightly
>> beneficial SNR. If not, I apologize for taking up the space.
>>
>> -Bob N3XKB
>>
>> On Tue, Oct 8, 2019 at 10:22 AM Jim Barber <barberaudio@gmail.com> wrote:
>>
>>> I'm laying out a 2-module MOSFET amp, and intend to use liquid cooling.
>>>
>>> The last time I visited the topic, ethylene glycol antifreeze diluted with
>>> the traditional 50% deionized water was the coolant of choice.
>>>
>>> Anything new under the sun? I'm using propylene glycol in my laser tube
>>> and CNC spindle coolers, but those don't have to be very efficient. The
>>> cooling system for the amp is going to have to move some heat.
>>>
>>> Thanks,
>>> Jim N7CXI
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>
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