[Johnson] Transformer "cooking"

[David C. Hallam]

I really couldn't see getting the iron that hot.  I will get it to the 
point where it is warm to the touch and hold it there.

David
KW4DH

On 1/7/2014 12:21 PM, Carl wrote:
> I would not suggest running at maximum current as moisture saturated 
> fishpaper insulation is already compromised. Get the iron just hot 
> enough and a bit over to do the job.
>
> Carl
> KM1H
>
>
>
> ----- Original Message ----- From: "David C. Hallam" 
> <dhallam at knology.net>
> To: "Mike Pagel, K9UW" <k9uw at wi-net.com>; <johnson at mailman.qth.net>
> Sent: Tuesday, January 07, 2014 8:07 AM
> Subject: Re: [Johnson] Transformer "cooking"
>
>
>> Mike,
>>
>> Yes, that was what I remembered.  I have a transformer that has been 
>> sitting in my garage for several years that I need to dry out.  I'm 
>> starting a linear project.
>>
>> David
>> KW4DH
>>
>> On 1/6/2014 9:28 PM, Mike Pagel, K9UW wrote:
>>> Is this the information you were thinking of, David?
>>>
>>> http://lists.contesting.com/_amps/2005-09/msg00203.html
>>>
>>> 73, de Mike, K9UW
>>> Amherst, WI
>>>
>>> -----Original Message----- From: David C. Hallam
>>> Sent: Monday, January 06, 2014 7:17 AM
>>> To: johnson at mailman.qth.net
>>> Subject: Re: [Johnson] Transformer "cooking"
>>>
>>> Rich Measures put out some information on how he dries out old power
>>> transformers by applying AC with a variac.  It's probably in the
>>> ham_amplifiers archives some where or maybe on his web site.
>>>
>>> David
>>> KW4DH
>>>
>>> On 1/5/2014 11:28 PM, Richard Knoppow wrote:
>>>>
>>>> ----- Original Message ----- From: "Brian Burns" 
>>>> <brian at lessonsinlutherie.com>
>>>> To: <johnson at mailman.qth.net>
>>>> Sent: Sunday, January 05, 2014 11:55 AM
>>>> Subject: [Johnson] Transformer "cooking"
>>>>
>>>>
>>>>> Hello Richard et al,
>>>>>
>>>>> I heard on the air a few months ago a suggestion for drying out a 
>>>>> modulation
>>>>> transformer, and was wondering if it is just an "Olde Ham's Tale". 
>>>>> The ham
>>>>> that was suggesting it shall remain call-less.
>>>>>
>>>>> The suggestion: Short the secondary, and apply a few metered volts 
>>>>> to the
>>>>> primary with a Variac.  Raise the voltage in small steps, with 
>>>>> extended
>>>>> intervals of time for temperature stabilization. When the 
>>>>> transformer gets
>>>>> warm to the touch, let it sit for a long period of time (days?) to 
>>>>> dry it
>>>>> out thoroughly.
>>>>>
>>>>> Whaddaya think?
>>>>>
>>>>> Cheers,
>>>>
>>>>     Would scare me to do.  If there is suspicion that there is 
>>>> moisture in a transformer I would remove it and bake it out. The 
>>>> ideal is an electric oven with thermostat control but it can be 
>>>> done with a makeshift using lamps to supply heat. The heat should 
>>>> not be too high, you don't want to melt out any insulation. Say 
>>>> around 150F for a few days.
>>>>     While pure water is not conductive even a small amount of any 
>>>> salt will make it quite conductive.  I suspect most transformer 
>>>> failures that are not from plain old overloading or arc overs are 
>>>> from old insulation crumbling. It would be interesting to hear from 
>>>> someone who has done a lot of re-winding on what he found.
>>>>
>>>>
>>>> -- 
>>>> Richard Knoppow
>>>> Los Angeles
>>>> WB6KBL
>>>> dickburk at ix.netcom.com
>>>> ______________________________________________________________
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>>>
>>
>> -- 
>> "I predict future happiness for Americans if they can prevent the 
>> government from wasting the labors of the people under the pretense 
>> of taking care of them."
>> Thomas Jefferson
>>
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>

-- 
"I predict future happiness for Americans if they can prevent the government from wasting the labors of the people under the pretense of taking care of them."
Thomas Jefferson


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